Diseases detected by the GeneScreen test

What is 3-Beta-Hydroxysteroid Dehydrogenase Type II Deficiency?

3-Beta-Hydroxysteroid Dehydrogenase Type II Deficiency is an autosomal recessive condition.  It is one of a group of inherited disorders called Congenital Adrenal Hyperplasia that affect the hormones made by the ovaries, testes, and adrenal glands.  People with 3-Beta-Hydroxysteroid Dehydrogenase Type II Deficiency do not make enough of certain hormones needed by the body. There are three forms of this condition: salt-wasting, non-salt-wasting, and non-classical.  Babies with the salt-wasting form have symptoms that start shortly after birth and include poor feeding, vomiting, and dehydration which can lead to death if not treated. People with the non-salt-wasting and non-classical forms do not have these symptoms.  All three forms result in decreased amounts of sex hormones. This leads to abnormal development of the genitals in males which sometimes results in external genitals that look female instead of male (ambiguous genitalia).  Without treatment, both males and females with this condition do not go through normal puberty and often cannot have their own children. Without treatment, high blood pressure and low potassium levels are also common.  People with the non-classical form of the condition have symptoms that are typically milder than the other two forms. Treatment includes hormone replacement therapies and sometimes other supplements or medications.

What causes 3-Beta-Hydroxysteroid Dehydrogenase Type II Deficiency?

3-Beta-Hydroxysteroid Dehydrogenase Type II Deficiency is caused by a gene change, or mutation, in both copies of the HSD3B2 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is 3-Hydroxy-3-Methylglutaryl-Coenzyme A Lyase Deficiency?

3-Hydroxy-3-Methylglutaryl-Coenzyme A (HMG-CoA) Lyase Deficiency is an autosomal recessive condition.  It is one of a group of inherited disorders known as Organic Acid Disorders.  People with HMG-CoA Lyase Deficiency cannot break down leucine, one of the building blocks of protein, and cannot use body fat as energy.  Signs and symptoms often start in infancy or early childhood and include lack of energy, poor feeding, poor muscle tone, diarrhoea, vomiting, low blood sugar (hypoglycemia), breathing problems, seizures, and coma, which, if left untreated, can lead to death.  Episodes of low blood sugar and metabolic acidosis, where toxic substances build up in the blood, can be triggered by going a long time without food (fasting), illness, or eating large amounts of protein.  If the condition is not treated, repeated episodes of metabolic acidosis can lead to an enlarged heart and liver, vision and hearing loss, and intellectual disability.  Symptoms vary from person to person and some people never show symptoms.  Treatment includes a medical diet low in protein and fat, other supplements and medications, and avoidance of fasting.  If treatment is started early, people with this condition can often live healthy lives.  However, even with careful treatment, some children still have repeated episodes of metabolic acidosis and low blood sugar.

What causes 3-Hydroxy-3-Methylglutaryl-Coenzyme A Lyase Deficiency?

HMG-CoA Lyase Deficiency is caused by a gene change, or mutation, in both copies of the HMGCL gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is 3-Methylcrotonyl-CoA Carboxylase 1 Deficiency?

3-Methylcrotonyl-CoA Carboxylase 1 Deficiency is an autosomal recessive condition.  It is one of a group of inherited disorders known as Organic Acid Disorders.  People with 3-Methylcrotonyl-CoA Carboxylase 1 Deficiency cannot break down a building block of a protein called leucine.  When food containing leucine is eaten, harmful substances build up in the blood causing repeated episodes of metabolic acidosis.  These episodes may include vomiting, lack of energy, muscle weakness, sleep disturbances, breathing problems, low blood sugar (hypoglycemia), seizures, coma, and sometimes even death.  These episodes are often triggered by eating large amounts of protein, going a long time without food (fasting), or illness. If not treated, this condition can lead to developmental delays and intellectual disability, poor growth, muscle problems, and liver failure. Symptoms can range from mild to severe and often begin in infancy or childhood, although some people do not have symptoms until adulthood and others never show symptoms. Treatment for children with 3-Methylcrotonyl-CoA Carboxylase 1 Deficiency who show symptoms includes a medical low-protein diet and specific supplements. Treatment can prevent or lessen the symptoms in most people with this condition although some still have repeated episodes of metabolic acidosis even with careful treatment.   

What causes 3-Methylcrotonyl-CoA Carboxylase 1 Deficiency?

3-Methylcrotonyl-CoA Carboxylase 1 Deficiency is caused by a gene change, or mutation, in both copies of the MCCC1 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is 3-Methylcrotonyl-CoA Carboxylase 2 Deficiency?

3-Methylcrotonyl-CoA Carboxylase 2 Deficiency is an autosomal recessive condition.  It is one of a group of inherited disorders known as Organic Acid Disorders.  People with 3-Methylcrotonyl-CoA Carboxylase 2 Deficiency cannot break down a building block of a protein called leucine.  When food containing leucine is eaten, harmful substances build up in the blood causing repeated episodes of metabolic acidosis.  These episodes may include vomiting, lack of energy, muscle weakness, sleep disturbances, breathing problems, low blood sugar (hypoglycemia), seizures, coma, and sometimes even death.  These episodes are often triggered by eating large amounts of protein, going a long time without food (fasting), or illness. If not treated, this condition can lead to developmental delays and intellectual disability, poor growth, muscle problems, and liver failure. Symptoms can range from mild to severe and often begin in infancy or childhood, although some people do not have symptoms until adulthood and others never show symptoms. Treatment for children with 3-Methylcrotonyl-CoA Carboxylase 2 Deficiency who show symptoms includes a medical low-protein diet and specific supplements. Treatment can prevent or lessen the symptoms in most people with this condition although some still have repeated episodes of metabolic acidosis even with careful treatment.   

What causes 3-Methylcrotonyl-CoA Carboxylase 2 Deficiency?

3-Methylcrotonyl-CoA Carboxylase 2 Deficiency is caused by a gene change, or mutation, in both copies of the MCCC2 gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work properly, it leads to the symptoms described above.

What is 3-Phosphoglycerate Dehydrogenase Deficiency?

3-Phosphoglycerate Dehydrogenase Deficiency is an autosomal recessive disorder that affects the brain and nervous system.  Signs and symptoms usually begin infancy and include small head size (microcephaly), developmental delays, growth delay, intellectual disability, and seizures.  The brain develops abnormally and over time there is loss of brain tissue.  Affected infants may not achieve developmental milestones such as speech or sitting up without assistance.  In rare cases, symptoms do not begin until childhood or adulthood.  Currently, there is no cure for this condition; however, amino acid therapy may reduce seizures and other symptoms if treatment is started early in life.   

What causes 3-Phosphoglycerate Dehydrogenase Deficiency?

3-Phosphoglycerate Dehydrogenase Deficiency is caused by a change, or mutation, in both copies of the PHGDH gene pair.  These mutations cause the genes to not work properly or not work at all.  The normal function of the PHGDH genes is important for the development and function of the brain and spinal cord (central nervous system). When both copies of the PHGDH gene pair do not work correctly it leads to the symptoms described above. 

What is 6-Pyruvoyl-Tetrahydropterin Synthase (PTPS) Deficiency?

6-Pyruvoyl-Tetrahydropterin Synthase (PTPS) Deficiency is an autosomal recessive disorder in which the body cannot break down a specific building block of a protein called phenylalanine. Phenylalanine is the most protein found in the diet and, if it cannot be broken down, it builds up in the blood and causes damage to the brain and nervous system. If untreated, symptoms of PTPS Deficiency usually begin shortly after birth and include seizures, abnormal muscle tone, unusual movements, and intellectual disability. Early treatment with a special medical low-phenylalanine diet and other supplements can often prevent or lessen the severity of symptoms.  

What causes 6-Pyruvoyl-Tetrahydropterin Synthase (PTPS) Deficiency?

6-Pyruvoyl-Tetrahydropterin Synthase (PTPS) Deficiency is caused by a gene change, or mutation, in both copies of the PTS gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Abetalipoproteinemia?

Abetalipoproteinemia is a rare autosomal recessive disorder that prevents the body from completely absorbing certain dietary fats and the essential vitamins A, D, E, and K. Signs and symptoms of Abetalipoproteinemia usually begin in infancy but may first appear later in childhood, or rarely, not until adulthood. Symptoms include poor weight gain and diarrhoea along with abnormally shaped red blood cells (acanthocytosis). Affected children often have problems with balance, coordination, and walking due to problems with nerve function and muscle weakness. Anaemia and a type of vision loss called Retinitis Pigmentosa may also occur.  Treatment to attempt to slow down the progression of symptoms includes supplementation with fat-soluble vitamins and other supplements along with a special low-fat medical diet. 

What causes Abetalipoproteinemia?

Abetalipoproteinemia is caused by a gene change, or mutation, in both copies of the MTTP gene pair. These mutations cause the genes to not work properly or not work at all.  The MTTP genes are important in helping the body absorb fats, cholesterol, and fat-soluble vitamins from the diet.  When both copies of the MTTP gene pair do not work correctly, it leads to the symptoms described above. 

What is Achondrogenesis, Type 1B?

Achondrogenesis, Type 1B is an autosomal recessive disorder that affects cartilage and bone. Signs and symptoms of this disorder include abnormal bone and joint development, a small rib cage that may cause breathing problems in the newborn period, short stature, short arms and legs, curvature of the spine (scoliosis), painful joints that restrict movement and early arthritis that worsens over time. Bone and cartilage abnormalities may also occur in the hands, feet, outer portions of the ears, head, and face. Intelligence is not affected. Currently, there is no cure or specific treatment for Achondrogenesis, Type IB.

Three other related but less common inherited disorders are sometimes caused by specific mutations in the same gene. Diastrophic Dysplasia includes short stature, joint restrictions (contractures), cleft palate and other minor features. Atelosteogenesis Type 2 has symptoms similar to Diastrophic Dysplasia but is fatal in the newborn period. Recessive Multiple Epiphyseal Dysplasia includes short stature, joint pain, the curvature of the spine, abnormalities of the hands, feet, and knees, and sometimes other birth defects.  

What causes Achondrogenesis, Type 1B?

Achondrogenesis, Type 1B is caused by a gene change, or mutation, in both copies of the SLC26A2 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work properly, it leads to the symptoms described above. 

What is Achromatopsia, CNGB3-Related?

Achromatopsia, CNGB3-Related is an autosomal recessive condition that causes a partial or complete loss of colour vision.  Most people with this condition have complete Achromatopsia and can only see in shades of black, white, and gray.  Other vision problems seen with Achromatopsia, CNGB3-Related include light sensitivity, reduced sharpness of vision, involuntary shaking movements of the eye (nystagmus), farsightedness or, less commonly, nearsightedness. It is common for light sensitivity and nystagmus to appear within the first few weeks or months of life, although this may improve slightly over time.  Achromatopsia, CNGB3-Related is not the same as colourblindness, a condition where colour can be seen but it is difficult to distinguish between certain colours. Currently, there is no cure for this condition. Although rare, some individuals will have incomplete Achromatopsia with the ability to perceive some colour. Also rare is another form of the disorder called Progressive Cone Dystrophy where the loss of colour doesn’t begin until childhood or teenage years.

What causes Achromatopsia, CNGB3-Related?

Achromatopsia, CNGB3-Related is caused by mutations in both copies of the CNGB3 gene pair. These mutations cause the CNGB3 genes to not work properly or not work at all.  When both copies of the CNGB3 gene pair do not work correctly, it causes the symptoms described above. 

What is Acrodermatitis Enteropathica?

Acrodermatitis Enteropathica is an autosomal recessive disorder that causes a deficiency of zinc in the body. People with this condition cannot absorb zinc from food.  If the condition is not treated, symptoms appear in infancy and include irritability, diarrhoea, hair loss, poor growth, abnormal nails, recurrent infections, and irritation of the skin called dermatitis. The skin problems, which include dry scaly skin and pimple-like lesions that may blister, occur most often around the mouth and anus. Psychological and neurological problems may also occur. Treatment with zinc supplements can prevent or improve symptoms. People with this condition who are treated can often live healthy lives.  Without treatment, this condition can be fatal.

What causes Acrodermatitis Enteropathica?

Acrodermatitis Enteropathica is caused by a gene change, or mutation, in both copies of the SLC39A4 gene pair.  These mutations cause the genes to not work properly or not work at all.  The normal function of the SLC39A4 genes is necessary for the body to absorb zinc. When both copies of the SLC39A4 gene do not work correctly, the body is unable to absorb zinc which leads to the symptoms described above. 

What is Acute Infantile Liver Failure, TRMU-Related?

Acute Infantile Liver Failure, TRMU-Related is an autosomal recessive disorder that causes temporary life-threatening liver failure in infants. Signs and symptoms show up shortly after birth. Babies with this condition have problems with feeding, vomiting, irritability, jaundice, lethargy, a distended abdomen, and abnormal laboratory results showing acute liver failure. Although the condition can be fatal, with proper medical treatment most infants survive the acute episode of liver failure. Children who survive usually do not have any further episodes of liver failure and have normal growth and development.   

What causes Acute Infantile Liver Failure, TRMU-Related?

Acute Infantile Liver Failure, TRMU-Related is caused by a gene change, or mutation, in both copies of the TRMU gene pair. These mutations cause the genes to not work properly or not work at all. If both copies of the TRMU gene pair do not work correctly, it leads to the symptoms described above. 

What is Acyl-CoA Oxidase I Deficiency?

Acyl-CoA Oxidase I Deficiency is an autosomal recessive disorder that causes the buildup of certain fatty substances in the body.  This causes damage to the brain that worsens with time.  Babies with this condition typically have problems feeding and gaining weight, poor muscle tone, seizures, and a distinctive facial appearance.  Some babies have extra fingers or toes, and some have an enlarged liver.  Over time, the coating around the nerves (myelin) in the brain and body breaks down.  This leads to loss of milestones and skills starting around the age of two years and intellectual and physical disabilities that worsen over time.  Hearing and vision loss may also occur. Lifespan is shortened and many children with Acyl-CoA Oxidase I Deficiency do not survive past childhood. Currently, there is no cure for this condition.

What causes Acyl-CoA Oxidase I Deficiency?

Acyl-CoA Oxidase I Deficiency is caused by a gene change, or mutation, in both copies of the ACOX1 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Adrenoleukodystrophy, X-Linked?

Adrenoleukodystrophy (ALD), X-Linked is an X-linked inherited disorder found most often in boys that mainly affects the nervous system and the adrenal glands, the small organs located on top of each kidney. In this disorder, the fatty covering (called myelin) that protects the nerves in the brain and spinal cord starts to break down. This causes problems when the nerves send information to the brain. In addition, damage to the outer layer of the adrenal glands causes a lack of certain hormones. Lower amounts of these hormones may cause weakness, weight loss, skin changes, vomiting, and coma. It is more common for boys to be affected than girls. In some cases, individuals with Adrenoleukodystrophy, X-Linked have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

There are three different types of ALD, X-Linked: a childhood cerebral form, and adrenomyeloneuropathy (AMN) type, and a form called Addison disease.

Childhood Cerebral Form: Children with this type of ALD have learning and behaviour problems that usually begin between the age of 4 and 10 years. Other symptoms include vision problems, difficulty swallowing, and poor coordination, all of which worsen over time. In addition, the adrenal glands start working improperly, which can cause vomiting, weakness, or coma. This type of ALD can progress rapidly and lifespan is shortened.

AMN Type: People with this type of ALD develop progressive stiffness and weakness in their legs, urinary and reproductive tract problems, and problems with behaviour and thinking starting in early adulthood or middle age. Most people with this type of ALD have adrenal glands that work improperly leading to vomiting, weakness, or coma. In some severely affected individuals, damage to the brain and nervous system leads to early death.

Addison disease: The first symptoms of Addison disease are vomiting and weakness or coma caused by improperly working adrenal glands. Symptoms can begin anytime between childhood and adulthood. By middle age, most people have additional symptoms of ALD. 

Although most female carriers have no symptoms, some carriers may develop mild symptoms of ALD, X-Linked.

What causes Adrenoleukodystrophy, X-Linked?

Adrenoleukodystrophy (ALD), X-Linked is caused by a change, or mutation, in the ABCD1 gene. This mutation causes the gene to not work properly or not work at all. People with ALD, X-Linked cannot break down certain fats called very long-chain fatty acids (VLCFAs). These fats build up in the body and can damage the adrenal glands and fatty covering around the nerves and brain and lead to the signs and symptoms of ALD, X-Linked. 

What is Aicardi-Goutières Syndrome?

Aicardi-Goutières Syndrome is an autosomal recessive disorder that affects the brain, immune system, and skin. Symptoms often first appear in infancy and include severe irritability, poor feeding, vomiting, fever, and seizures.  Episodes of brain inflammation (encephalopathy) cause slowed brain growth and small head size (microcephaly), delayed development, loss of skills, and inability to walk.  Most children with Aicardi-Goutières Syndrome have severe intellectual disability, muscle stiffness (spasticity), involuntary muscle spasms called dystonia and abnormal eye movements. They may also have painful or itchy skin patches called chilblains on their fingers, toes and ears. Lifespan is shortened. Children with this condition often do not survive past childhood, although people with milder symptoms may live into adulthood.  Currently, there is no cure or specific treatment for this condition.

What causes Aicardi-Goutières Syndrome?

Aicardi-Goutières Syndrome is caused by a gene change, or mutation, in the SAMHD1 gene.  These mutations cause the gene to not work properly or not work at all.  When both copies of the SAMHD1 gene do not work correctly, an abnormal immune and inflammatory response in the brain and skin occurs and leads to the symptoms described above

What is Alpha-Mannosidosis?

Alpha-Mannosidosis is an autosomal recessive disorder that causes a toxic buildup of certain types of sugars, called oligosaccharides, in the body.  There are mild and severe forms of Alpha-Mannosidosis with signs and symptoms typically beginning in infancy or later in childhood.  In rare cases, symptoms may not begin until adulthood.  Many parts of the body are affected leading to distinctive facial features, intellectual disability, developmental delays, bone abnormalities, movement problems, muscle weakness, joint problems, frequent infections, psychiatric problems, and hearing loss.  The condition worsens with time.  People with Alpha-Mannosidosis often require a wheelchair.  Death may occur in childhood; however, lifespan may be near normal in individuals with a milder form of the condition. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Alpha-Mannosidosis?

Alpha-Mannosidosis is caused by a change, or mutation, in both copies of the MAN2B1 gene pair.  These mutations cause the genes to not work properly or not work at all.  The function of the MAN2B1 genesis is to create an enzyme that breaks down certain sugars and clears them from the body. When both copies of this gene pair do not work properly, it causes a buildup of specific sugars in the body causing cell damage in many organs. This leads to the symptoms described above.

What is Alpha-Thalassemia?

Alpha-Thalassemia refers to a group of autosomal recessive inherited blood disorders that result in a reduction in the amount of haemoglobin, the protein in red blood cells that carries oxygen to cells throughout the body. A person with one of the Alpha-Thalassemia diseases has lifelong anaemia. Mild anaemia can lead to tiredness, irritability, dizziness, lightheadedness and a rapid heartbeat. Severe anaemia can be life-threatening and may require routine blood transfusions.  The most severe form is usually lethal during pregnancy or shortly after birth unless treatment is started during pregnancy. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

Carriers of Alpha-Thalassemia can sometimes have mild anaemia.

What causes Alpha-Thalassemia?

Haemoglobin is made of both alpha-globin and beta-globin proteins. There are four HBA genes (also called alpha-globin genes) that are responsible for making alpha-globin.  Alpha-Thalassemia occurs when three or more of these four HBA genes are missing or changed, or when a person has changes, or mutations, called Constant Spring mutations, in two of the four genes. The exact type of Alpha-Thalassemia a person has depends on how many of the HBA (alpha-globin) genes are not working. Some common types of Alpha-Thalassemia are:

Haemoglobin H Disease: caused by three missings or changed alpha-globin genes. A person who has three missing or changed alpha globin genes has Hemoglobin H Disease. Haemoglobin H disease can be mild or severe. People with severe disease may have chronic anaemia, liver disease, and bone changes. Some people with Hemoglobin H Disease require frequent blood transfusions and other treatments.

Haemoglobin H-Constant Spring Disease: caused by two missing alpha-globin genes and one Constant Spring mutation. A person with these gene findings has Hemoglobin H-Constant Spring Disease. This condition is usually more severe than Hemoglobin H Disease. A person with this condition typically has chronic anaemia, is more likely to need blood transfusions, has more frequent viral infections, and may have an enlarged spleen.

Homozygous Constant Spring Disease: caused by two Constant Spring mutations. A person with Homozygous Constant Spring Disease has mild to severe anaemia and symptoms similar to those seen in Hemoglobin H Disease described above.

Alpha-Thalassemia Major, also known as Hemoglobin Bart’s Disease: caused by four missings or changed alpha-globin genes. This results in very severe anaemia. Affected babies develop symptoms before birth and unless treatment is started during pregnancy these babies are usually either stillborn or do not survive the newborn period. Mothers pregnant with a fetus with Alpha-Thalassemia Major can develop health problems during pregnancy.

What is Alpha-Thalassemia Intellectual Disability Syndrome?

Alpha-Thalassemia Intellectual Disability (ATRX) Syndrome is a rare X-linked disorder that affects mainly boys. It causes significant intellectual disability and delays in all areas of development. Many boys with this condition speak few, if any, words and some are unable to walk on their own. Common features of this condition include a smaller than average head size, short stature, clubbed feet, abnormalities of the genitals, and muscle weakness (hypotonia). About 85% of boys with Alpha-Thalassemia Intellectual Disability Syndrome also have a blood disorder called Alpha-Thalassemia, a type of anaemia. Although some children with this condition are less severely affected than others, most need lifelong medical treatment.

Female carriers for Alpha-Thalassemia Intellectual Disability Syndrome typically do not have any symptoms. However, there are rare female carriers who have mild anaemia or intellectual disability.

What causes Alpha-Thalassemia Intellectual Disability Syndrome?

Alpha-Thalassemia Intellectual Disability Syndrome is caused by a change, or mutation, in the ATRX gene. This mutation causes the gene to not work properly or not work at all, which results in the symptoms described above.

What is Alport Syndrome, COL4A3-Related?

Autosomal recessive Alport Syndrome, COL4A3-Related is an inherited disorder that affects the kidneys, eyes, and ears. This condition causes progressive loss of kidney function which leads to blood and protein in the urine. Over time, the kidneys no longer work properly and dialysis or kidney transplant is often needed, typically in early to late adulthood. Sensorineural hearing loss usually occurs in late childhood or early teens, but hearing aids are helpful.  Eye problems include increased risk for cataracts, abnormally shaped lenses, and wearing away of the cornea.  People with Alport syndrome often need glasses, but it is rare for them to have vision loss. 

Autosomal dominant Alport Syndrome, COL4A3-Related is a less common form of this disorder caused by a mutation in the same gene.  People with the autosomal dominant form have less severe symptoms that progress more slowly.  Kidney disease and hearing loss may not occur until late adulthood and eye problems are rare. 

What causes Alport Syndrome, COL4A3-Related?

Autosomal recessive Alport Syndrome, COL4A3-Related is caused by a gene change, or mutation, in both copies of the COL4A3 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms of autosomal recessive Alport Syndrome, COL4A3-Related described above. 

In some cases of Alport Syndrome, COL4A3-Related is inherited in an autosomal dominant manner.  This means that a person who has a mutation in just one copy of the COL4A3 gene is affected with Alport Syndrome and has symptoms of Alport Syndrome. 

What is Alport Syndrome, COL4A4-Related?

Autosomal recessive Alport Syndrome, COL4A4-Related is an inherited disorder that affects the kidneys, eyes, and ears. This condition causes progressive loss of kidney function which leads to blood and protein in the urine. Over time, the kidneys can no longer work properly and dialysis or kidney transplant is often needed, typically in early to late adulthood. Sensorineural hearing loss usually occurs in late childhood or early teens, but hearing aids are helpful.  Eye problems include increased risk for cataracts, abnormally shaped lenses, and wearing away of the cornea.  People with Alport Syndrome often need glasses, but it is rare for them to have vision loss. 

Autosomal dominant Alport Syndrome, COL4A4-Related is a less common form of this disorder caused by a mutation in the same gene.  People with the autosomal dominant form have less severe symptoms that progress more slowly.  Kidney disease and hearing loss may not occur until late adulthood and eye problems are rare. 

What causes Alport Syndrome, COL4A4-Related?

Autosomal recessive Alport Syndrome, COL4A4-Related is caused by a gene change, or mutation, in both copies of the COL4A4 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms of autosomal recessive Alport Syndrome, COL4A4-Related described above. 

In some cases of Alport Syndrome, COL4A4-Related is inherited in an autosomal dominant manner.  This means that a person who has a mutation in just one copy of the COL4A4 gene is affected with Alport Syndrome and has symptoms of autosomal dominant Alport Syndrome. 

What is Alport Syndrome, X-Linked?

Alport Syndrome, X-Linked is an X-linked inherited condition that affects the kidneys, ears, and eyes. Alport Syndrome, X-Linked causes progressive loss of kidney function which leads to blood and protein in the urine. Over time, the kidneys can no longer work properly and dialysis or kidney transplant is often needed, typically in early to late adulthood. Sensorineural hearing loss usually occurs in late childhood or early teens, but hearing aids are typically effective. Eye problems include increased risk for cataracts, abnormally shaped lenses, and wearing away of the cornea. People with Alport Syndrome, X-Linked often need glasses, but it is rare for them to have vision loss.  Alport Syndrome, X-Linked is more common in boys than girls. 

What causes Alport Syndrome, X-Linked?

Alport Syndrome, X-Linked is caused by a change, or mutation, in the COL4A5 gene. This mutation causes the gene to not work properly or not work at all.  The normal function of the COL4A5 gene is to help make Type IV collagen. Type IV collagen is needed in the kidney, inner ear, and eye in order for these organs to work properly.   When the COL4A5 gene is not working correctly in a male, it leads to the symptoms described above. Some female carriers may have clinical symptoms associated with Alport Syndrome, X-Linked such as blood in the urine, which is common in carriers, or kidney disease or hearing loss, which are less common.

What is Alport Syndrome, X-Linked?

Alport Syndrome, X-Linked is an X-linked inherited condition that affects the kidneys, ears, and eyes. Alport Syndrome, X-Linked causes progressive loss of kidney function which leads to blood and protein in the urine. Over time, the kidneys can no longer work properly and dialysis or kidney transplant is often needed, typically in early to late adulthood. Sensorineural hearing loss usually occurs in late childhood or early teens, but hearing aids are typically effective. Eye problems include increased risk for cataracts, abnormally shaped lenses, and wearing away of the cornea. People with Alport Syndrome, X-Linked often need glasses, but it is rare for them to have vision loss.  Alport Syndrome, X-Linked is more common in boys than girls. 

What causes Alport Syndrome, X-Linked?

Alport Syndrome, X-Linked is caused by a change, or mutation, in the COL4A5 gene. This mutation causes the gene to not work properly or not work at all.  The normal function of the COL4A5 gene is to help make Type IV collagen. Type IV collagen is needed in the kidney, inner ear, and eye in order for these organs to work properly.   When the COL4A5 gene is not working correctly in a male, it leads to the symptoms described above. Some female carriers may have clinical symptoms associated with Alport Syndrome, X-Linked such as blood in the urine, which is common in carriers, or kidney disease or hearing loss, which are less common.

What is Alstrom Syndrome?

Alstrom Syndrome is an autosomal recessive disorder that affects many parts of the body. Signs and symptoms vary from person to person and usually begin in infancy or childhood. Children with Alstrom Syndrome typically have vision and hearing loss that worsens with time. A type of heart disease called dilated cardiomyopathy develops in some. Diabetes, obesity, breathing problems, liver disease, kidney disease, and short stature are common. Intelligence is not affected. Adults may have progressive liver and kidney disease that can lead to the failure of these organs. Depending on the severity of symptoms, lifespan may be shortened. Currently, there is no cure for Alstrom Syndrome although treatment is available for some of the medical problems that occur with this disorder.

What causes Alstrom Syndrome?

Alstrom Syndrome is caused by a gene change, or mutation, in both copies of the ALMS1 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Andermann Syndrome?

Andermann Syndrome, also known as Hereditary Motor and Sensory Neuropathy with Agenesis of the Corpus Callosum, is an autosomal recessive disorder that affects the brain and nervous system. Symptoms usually begin shortly after birth and include poor muscle tone and weakness with loss of feeling in the arms and legs. Underdevelopment of the corpus callosum (the part of the brain that connects the left and right sides) is common and reflexes are either absent or abnormal. Intellectual disability ranges from mild to severe and some children have seizures. Delays in learning to walk are common and teenagers often lose the ability to walk and may need the use of a wheelchair. Teens may have episodes of depression, anxiety, or hallucinations. People with Andermann Syndrome often live into adulthood but lifespan is usually decreased. Currently, there is no cure or specific treatment for this condition.

What causes Andermann Syndrome?

Andermann syndrome is caused by a gene change, or mutation, in both copies of the SLC12A6 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Argininosuccinate Lyase Deficiency?

Argininosuccinate Lyase Deficiency is an autosomal recessive disorder in which the body is unable to remove ammonia.  Too much ammonia in the body and blood causes damage to the body’s organs. 

Symptoms of Argininosuccinate Lyase Deficiency most often begin in the first few days after birth. Some children with this condition may have a milder form in which symptoms begin in late infancy or early childhood.  Newborns with symptoms may have vomiting, lethargy, irritability, or poor appetite.  If untreated, symptoms may worsen to include seizures, difficulty staying warm, muscle weakness, breathing problems, swelling of the brain, coma, or death within the first few weeks of life.  For those with late infancy or childhood-onset disease, symptoms may include intellectual disability, behaviour problems, hyperactivity, enlarged liver or liver disease, poor growth, dry and brittle hair, small head size, avoidance of meat or other high protein foods, and/or episodes of high ammonia in the blood.  Without treatment, life-threatening problems such as difficulty breathing, swelling of the brain, and seizures may develop.

What causes Argininosuccinate Lyase Deficiency?

Argininosuccinate Lyase Deficiency is caused by changes, or mutations, in both copies of the ASL gene pair.  These mutations cause the genes to not work properly or not work at all.  The normal function of the ASL gene is necessary to help remove ammonia from the body.  When both copies of the ASL gene are not working correctly, ammonia builds up in the body and leads to the symptoms described above. 

What is Aromatase Deficiency?

Aromatase Deficiency is an autosomal recessive disorder that leads to decreased female sex hormones and increased male sex hormones in the body.  Aromatase is an enzyme which converts the male sex hormone androgen into the female sex hormone estrogen, which is important for female development before birth and during puberty.  Estrogen is also important for bone growth and maintaining normal blood sugar levels in the body.

Females with Aromatase Deficiency may have external genitals that are not clearly female or male, along with normal internal female organs.  Without treatment, breast growth and menstrual cycles typically do not occur.  Females may also experience acne and excessive body hair growth.  In most cases, males with Aromatase Deficiency are born with normal external male genitals.  However, some males will have decreased sex drive, abnormal sperm production, or small undescended testes. Both females and males with Aromatase Deficiency may have abnormal bone growth resulting in tall stature, thinning of the bones with increased fractures (bone breaks), and delayed bone age.  People with Aromatase Deficiency may have abnormally high blood sugar levels, excess weight gain, and a fatty liver.  Estrogen replacement therapy can help to reverse some symptoms of this condition.

Pregnant women carrying a child with Aromatase Deficiency may temporarily have symptoms of this condition starting as early as 12 weeks gestation. This is caused by excess male sex hormones in the placenta.  These symptoms may include a deepened voice, acne, an enlarged clitoris, or excess hair growth and typically go away following delivery of the affected child. 

What causes Aromatase Deficiency?

Aromatase Deficiency is caused by a gene change, or mutation, in both copies of the CYP19A1 gene pair.  These mutations cause the genes to not work properly or not work at all.  If both copies of the CYP19A1 gene do not work correctly, it leads to the symptoms described above.

What is Asparagine Synthase Deficiency?

Asparagine Synthase Deficiency is an autosomal recessive disorder that affects the brain.  Signs and symptoms usually begin in infancy and include small head size, severe developmental delay, abnormal brain development, poor muscle tone, and seizures.  Affected children often have feeding problems and breathing problems.  Death may occur in infancy or childhood.  Currently there is no cure for this condition and treatment is based on symptoms.

What causes Asparagine Synthase Deficiency?

Asparagine Synthetase Deficiency is caused by a change, or mutation, in both copies of the ASNS gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Aspartylglycosaminuria?

Aspartylglycosaminuria is an autosomal recessive disorder in which the body is unable to break down certain types of proteins, called glycoasparagines, in the cells, leading to a toxic buildup in the body.  People with Aspartylglycosaminuria typically have normal development in infancy but develop symptoms within the first few years of life.  These symptoms can include speech delays, coarse facial features, recurrent respiratory infections, eye abnormalities, spine deformity, behaviour problems, and intellectual disability.  Symptoms worsen with age, including the loss of most learned speech by adulthood and declining intellectual abilities.  Adults with Aspartylglycosaminuria may develop seizures, fragile bones, loose joints and skin, or movement problems.  Lifespan is reduced with this condition with most people with Aspartylglycosaminuria living to their thirties or forties.  Currently, there is no cure for this condition and treatment is based on symptoms.

What causes Aspartylglycosaminuria?

Aspartylglycosaminuria is caused by a gene change, or mutation, in both copies of the AGA gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene are not working correctly, the body lacks an important enzyme that helps to break down specific proteins in the body.  As a result, these proteins build up and cause damage to the body’s cells, especially the nerve cells in the brain, and cause the symptoms described above. 

What is Ataxia with Vitamin E Deficiency?

Ataxia with Vitamin E Deficiency is an autosomal recessive disorder that affects the body’s ability to use vitamin E.  When the body is unable to use vitamin E from the diet, damage can occur to the body’s cells, especially in the central nervous system (brain and spine).  Lack of vitamin E can cause problems with speech and movement, loss of reflexes in the legs, and loss of sensation in the arms and legs.  Signs and symptoms of Ataxia with Vitamin E Deficiency usually appear between the ages of 4 and 18 years.  In rare cases, symptoms may begin before or after this typical age range. Most people with this condition will develop coordination problems that worsen with age.  Some people with Ataxia with Vitamin E Deficiency develop vision loss (caused by the eye disorder known as retinitis pigmentosa), disease of the heart muscle (cardiomyopathy), or curvature of the spine.  The number and severity of symptoms in Ataxia with Vitamin E Deficiency vary from person to person. 

What causes Ataxia with Vitamin E Deficiency?

Ataxia with Vitamin E Deficiency is caused by a gene change, or mutation, in both copies of the TTPA gene pair.  These mutations cause the gene to not work properly or not work at all.  When both copies of the TTPA gene are not functioning correctly, the body lacks the protein necessary for sending vitamin E obtained from the diet to cells and tissues throughout the body.  Tissues that use vitamin E have a buildup of free radicals in their cells, leading to damage, especially to nerve cells in the brain and spinal cord.

What is Ataxia-Telangiectasia?

Ataxia-Telangiectasia is an autosomal recessive disorder that affects many parts of the body.  Signs and symptoms usually begin in the first year of life and include problems with movement and coordination (ataxia), slurred speech, and abnormal eye movements.  The ataxia worsens over time and affected children usually require a wheelchair by the teen years.  Groups of enlarged blood vessels called telangiectases develop on the skin and eyes.  People with Ataxia-Telangiectasia have a weakened immune system, may have frequent sinus and lung infections, are at increased risk to develop cancer, especially leukaemia and lymphoma, and are sensitive to the effects of radiation including X-rays. Lifespan is often shortened in this disorder. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

Female carriers of Ataxia-Telangiectasia are at increased risk for developing breast cancer. Male and female carriers of Ataxia-Telangiectasia may be sensitive to the effects of radiation and may be at higher risk for developing other types of cancer as well. Carriers also may have a higher risk for heart disease. 

What causes Ataxia-Telangiectasia?

Ataxia-Telangiectasia is caused by a change, or mutation, in both copies of the ATM gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the ATM gene do not work correctly it leads to the health problems described above.

What is Autism Spectrum, Epilepsy and Arthrogryposis?

Autism Spectrum, Epilepsy and Arthrogryposis is an inherited disorder that causes intellectual disability, autism, seizures, and abnormalities of the joints of the limbs. Arthrogryposis is the lack of a normal range of motion in one or more joints.  Affected children have involvement of most joints, especially those of the neck, fingers and toes. Currently, there is no cure for this condition and treatment is based on symptoms.

What causes Autism Spectrum, Epilepsy and Arthrogryposis?

Autism Spectrum, Epilepsy and Arthrogryposis are caused by a gene change, or mutation, in both copies of the SLC35A3 gene.  These mutations cause the genes to not work properly or not work at all. When both copies of the SLC35A3 gene do not work correctly, it leads to the symptoms described above.  

What is Autoimmune Polyglandular Syndrome, Type 1?

Autoimmune Polyglandular Syndrome, Type 1, also known as Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy, is an autosomal recessive disorder of the immune system in which the body attacks and damages its own tissues and organs.  Signs and symptoms typically begin during childhood or adolescence.  The three main areas of the body affected by this disorder include the skin, the parathyroid glands, and the adrenal glands.  Mucocutaneous candidiasis, a fungal infection, affects the skin and inside of the mouth and nose.  Hypoparathyroidism, caused by lack of hormones made by the parathyroid gland, leads to tingling of the lips, fingers, and toes; pain, cramping, and weakness of the muscles; and lack of energy.  Addison disease, caused by a lack of hormones from the adrenal glands, causes muscle weakness, loss of appetite, weight loss, low blood pressure, and bronzing of the skin.  Some people with this condition have only two of the three of the main problems listed above.  Some people also have other signs and symptoms that may include diabetes, thyroid problems, and digestive problems. Currently, there is no cure for this condition. Treatment is available to reduce symptoms and may include hormone replacement therapy and other medications and supplements as indicated.

What causes Autoimmune Polyglandular Syndrome, Type 1?

Autoimmune Polyglandular Syndrome, Type 1 is caused by a gene change, or mutation, in both copies of the AIRE gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay?

Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay is an autosomal recessive disorder that affects the muscles and nervous system.  Signs and symptoms usually begin in infancy or early childhood and worsen with age.  Children first have coordination and balance problems with unsteady walking (ataxia), spasticity (muscle tightness), and muscle weakness and wasting (atrophy). Speech problems and abnormal eye movements (nystagmus) also occur. Other symptoms may include vision problems due to a buildup of tissue on the retina, misshapen fingers, toes, and feet, loss of sensation in the legs, and in some cases mitral valve prolapse (leaky valve in the heart).  Intelligence is not affected.  Most people with Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay need the use of a wheelchair in adulthood. Currently, there is no cure for this disorder but there are treatments that can help lessen or delay some of the symptoms.

What causes Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay?

Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay is caused by a gene change, or mutation, in both copies of the SACS gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Bardet-Biedl Syndrome, BBS1-Related?

Bardet-Biedl Syndrome, BBS1-Related is one of a group of autosomal recessive disorders that affect many parts of the body.  Common signs and symptoms include progressive vision loss, obesity, extra fingers and/or toes (polydactyly), intellectual disability, kidney abnormalities, and male genital abnormalities.  Eyesight problems begin early in life and worsen with time.  People with this condition are usually legally blind by adolescence or early adulthood.  Males with this condition usually have reduced amounts of sex hormones and as a result, have underdeveloped genitals and infertility (inability to have biological children).  Increased weight gain often begins in early childhood and continues with age causing obesity and related health problems.  Other signs and symptoms include distinctive facial features, abnormal tooth development, behaviour problems, kidney disease, and less commonly, heart, liver, and bowel disease.  Intellectual disability can range from mild to severe. Currently, there is no cure or specific treatment for this condition.

What causes Bardet-Biedl Syndrome, BBS1-Related?

Bardet-Biedl Syndrome, BBS1-Related is caused by a gene change, or mutation, in both copies of the BBS1 gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of this gene pair do not work correctly, it leads to the symptoms described above. 

What is Bardet-Biedl Syndrome, BBS10-Related?

Bardet-Biedl Syndrome, BBS10-Related is one of a group of autosomal recessive disorders that affect many parts of the body.  Common signs and symptoms include progressive vision loss, obesity, extra fingers and/or toes (polydactyly), intellectual disability, kidney abnormalities, and male genital abnormalities.  Eyesight problems begin early in life and worsen with time.  People with this condition are usually legally blind by adolescence or early adulthood.  Males with this condition usually have reduced amounts of sex hormones and as a result, have underdeveloped genitals and infertility (inability to have biological children).  Increased weight gain often begins in early childhood and continues with age causing obesity and related health problems.  Other signs and symptoms include distinctive facial features, abnormal tooth development, behaviour problems, kidney disease, and, less commonly, heart, liver, and bowel disease.  Intellectual disability can range from mild to severe. Currently, there is no cure or specific treatment for this condition.

What causes Bardet-Biedl Syndrome, BBS10-Related?

Bardet-Biedl Syndrome, BBS10-Related is caused by a gene change, or mutation, in both copies of the BBS10 gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of this gene pair do not work correctly, it leads to the symptoms described above. 

What is Bardet-Biedl Syndrome, BBS12-Related?

Bardet-Biedl Syndrome, BBS12-Related is one of a group of autosomal recessive disorders that affect many parts of the body.  Common signs and symptoms include progressive vision loss, obesity, extra fingers and/or toes (polydactyly), intellectual disability, kidney abnormalities, and male genital abnormalities.  Eyesight problems begin early in life and worsen with time.  People with this condition are usually legally blind by adolescence or early adulthood.  Males with this condition usually have reduced amounts of sex hormones and as a result, have underdeveloped genitals and infertility (inability to have biological children).  Increased weight gain often begins in early childhood and continues with age causing obesity and related health problems.  Other signs and symptoms include distinctive facial features, abnormal tooth development, behaviour problems, kidney disease, and, less commonly, heart, liver, and bowel disease.  Intellectual disability can range from mild to severe. Currently, there is no cure or specific treatment for this condition.

What causes Bardet-Biedl Syndrome, BBS12-Related?

Bardet-Biedl Syndrome, BBS12-Related is caused by a gene change, or mutation, in both copies of the BBS12 gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of this gene pair do not work correctly, it leads to the symptoms described above. 

What is Bardet-Biedl Syndrome, BBS2-Related?

Bardet-Biedl Syndrome, BBS2-Related is one of a group of autosomal recessive disorders that affect many parts of the body.  Common signs and symptoms include progressive vision loss, obesity, extra fingers and/or toes (polydactyly), intellectual disability, kidney abnormalities, and male genital abnormalities.  Vision problems begin early in life and worsen with time.  People with this condition are usually legally blind by adolescence or early adulthood.  Males with this condition usually have reduced amounts of sex hormones and, as a result, have underdeveloped genitals and infertility (inability to have biological children).  Increased weight gain often begins in early childhood and continues with age, causing obesity and related health problems.  Other signs and symptoms include distinctive facial features, abnormal tooth development, behaviour problems, kidney disease, and, less commonly, heart, liver, and bowel disease.  Intellectual disability can range from mild to severe. Currently, there is no cure or specific treatment for this condition.

Very rarely, mutations in the same gene cause a different autosomal recessive disorder called Retinitis Pigmentosa 74.  This condition causes vision loss that begins with the loss of night vision and worsens over time, usually leading to blindness by adulthood.  Only a few families worldwide have been reported with Retinitis Pigmentosa 74.

What causes Bardet-Biedl Syndrome, BBS2-Related?

Bardet-Biedl Syndrome, BBS2-Related is caused by a gene change, or mutation, in both copies of the BBS2 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Bare Lymphocyte Syndrome, CIITA-Related?

Bare Lymphocyte Syndrome, CIITA-Related (also called Bare Lymphocyte Syndrome, Type II) is an autosomal recessive disorder of the immune system. It is one of a group of inherited disorders called Severe Combined Immunodeficiency (SCID). These disorders affect the body’s ability to fight off viral, bacterial and fungal infections. The signs and symptoms of Bare Lymphocyte syndrome, CIITA-Related usually begin in the first few months after birth. Infants and children with this disorder have frequent life-threatening infections that occur in many parts of the body - especially the respiratory tract, gastrointestinal tract, skin, kidneys, urinary tract, and brain. Children with this condition may have delayed growth and development because of problems with absorbing nutrients from food in the intestines. Death often occurs between 6 months to 5 years of age. Treatment with bone marrow or stem cell transplantation is possible for some children.

What causes Bare Lymphocyte Syndrome, CIITA-Related?

Bare Lymphocyte Syndrome, CIITA-Related is caused by a change, or mutation, in both copies of the CIITA gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the CIITA gene do not work correctly, it leads to the symptoms described above.

What is Bartter Syndrome, BSND-Related?

Bartter syndrome, BSND-Related (also known as Bartter Syndrome Type IV or Bartter Syndrome Type 4a) is an autosomal recessive disorder that causes kidney disease and hearing loss. Signs and symptoms usually begin prenatally and may include increased amniotic fluid, swelling of the fetus (hydrops), and premature birth. After birth, infants and children have slow growth and poor weight gain, hearing loss, and decreased muscle tone. They may also have abnormal facial features, developmental delay, and intellectual disability. Dehydration, an increased amount of urine, muscle weakness, fatigue, and weakened bones may also occur. Early diagnosis and treatment may improve the growth and development of infants and children with this condition.

 What causes Bartter Syndrome, BSND-Related?

Bartter Syndrome, BSND-Related is caused by a gene change, or mutation, in both copies of the BSND gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the BSND gene are not working correctly, it leads to the symptoms described above.

What is Batten Disease, CLN3-Related?

Batten Disease, CLN3-Related, also known as Juvenile Batten Disease,  is an autosomal recessive disorder that affects the brain and nervous system leading to progressive vision loss, intellectual disability, loss of intellectual and motor skills, speech problems, and seizures.  Children typically have normal development for several years and then symptoms involving vision, thinking, and movement begin and continue to worsen with age.  People with Batten Disease, CLN3-Related may live into their twenties or thirties.  Rarely, symptoms begin in infancy and are more severe.  Babies with early-onset of symptoms usually do not live past childhood. Currently, there is no cure for this condition and treatment is based on symptoms.

What causes Batten Disease, CLN3-Related?

Batten Disease, CLN3-Related is caused by a gene change or mutation in both copies of the CLN3 gene pair.  These mutations cause the genes to not work properly or not work at all.  The CLN3 gene is important for the brain and nervous system to function normally.  When both copies of the CLN3 gene do not work correctly, cells in the nervous system eventually die, leading to the symptoms described above. 

What are Beta-Hemoglobinopathies?

Beta-Hemoglobinopathies are a group of autosomal recessive conditions that cause mild to severe anaemia.  Mild anaemia can cause shortness of breath, tiredness, irritability, dizziness, lightheadedness, a rapid heartbeat, and, in children, delayed growth and development. Severe anaemia can be life-threatening and may require routine blood transfusions. Some forms of Beta-Hemoglobinopathy are very mild and may not cause symptoms or require treatment.  Other forms, such as Sickle Cell Disease and Beta-Thalassemia, cause more severe symptoms that often require medical treatment throughout life.  These symptoms can include severe anaemia, delayed growth and development, and a number of other health problems.  Early identification and treatment of children with severe forms of Beta-Hemoglobinopathy can often help lessen the severity of symptoms. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Beta-Hemoglobinopathies?

Beta-Hemoglobinopathies are caused by a change, or mutation, in both copies of the HBB gene.  These mutations cause the genes to not work properly or not work at all. When both copies of the HBB gene do not work correctly, it can lead to a Beta-Hemoglobinopathy, with symptoms ranging from very mild to severe.

Carriers for a Beta-Hemoglobinopathy, who have a mutation in only one copy of the HBB gene, may have mild anaemia that typically does not need treatment.  Rarely, carriers may have moderate anaemia that may or may not need treatment.

What is Beta-Ketothiolase Deficiency?

Beta-Ketothiolase Deficiency, also known as Ketothiolase Deficiency, is an autosomal recessive disorder in which the body cannot use a certain building block of a protein called isoleucine and also has problems breaking down fats from the diet.  Signs and symptoms of Beta-Ketothiolase Deficiency usually begin in the first or second year of life and include sleeping longer or more often, tiredness, vomiting, diarrhoea, fever, poor appetite, and breathing trouble.  Signs and symptoms may appear after going a long time without food, after intake of food high in protein, or during illness.  With early diagnosis and treatment, children with Beta-Ketothiolase Deficiency can lead healthy lives. 

What causes Beta-Ketothiolase Deficiency?

Beta-Ketothiolase Deficiency is caused by a gene change, or mutation, in both copies of the ACAT1 gene pair.  These mutations cause the genes to not work properly or not work at all. The normal function of the ACAT1 genes is to help break down fats and protein from the diet.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Bilateral Frontoparietal Polymicrogyria?

Bilateral Frontoparietal Polymicrogyria is an autosomal recessive disorder that causes abnormal development of the brain that starts before birth. The outer surface of the brain normally has ridges or folds, called gyri. In people with polymicrogyria, the brain develops too many folds that are too small in size. Bilateral Frontoparietal Polymicrogyria affects the frontal and parietal lobes on both sides of the brain. Signs and symptoms typically include developmental delay, moderate to severe intellectual disability, seizures, problems with muscle coordination, trouble with speech and swallowing, and eye problems including crossed eyes. There is no cure for this disorder and treatment is based on the symptoms.

What causes Bilateral Frontoparietal Polymicrogyria?

Bilateral Frontoparietal Polymicrogyria is caused by a gene change, or mutation, in both copies of the GPR56 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Biotinidase Deficiency?

Biotinidase Deficiency is an autosomal recessive disorder in which the body is unable to reuse a B vitamin called biotin.  This condition is treatable in affected infants and children by giving biotin.  If this condition is not identified in infancy and treated, signs and symptoms typically appear in the first few months of life but can sometimes begin later in childhood.

If untreated, Biotinidase Deficiency can cause delayed development, seizures, weak muscle tone (hypotonia), breathing problems, hearing and vision loss, problems with movement and balance, skin rashes, hair loss, and yeast infections.  Some children have a milder form of this condition, and some never develop symptoms.  Lifelong treatment with biotin supplements can prevent these complications from occurring. With early diagnosis and treatment with biotin, people with Biotinidase Deficiency can live healthy lives with no symptoms.

What causes Biotinidase Deficiency?

Biotinidase Deficiency is caused by a gene change, or mutation, in both copies of the BTD gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the BTD gene do not work correctly, it leads to the symptoms described above.

What is Bloom Syndrome?

Bloom Syndrome is an autosomal recessive disorder that causes growth delay, sensitivity to sunlight, immune system problems, increased risk for cancer, and sometimes intellectual disability. Most people with Bloom Syndrome live into adulthood but their lifespan may be decreased. Currently, there is no cure for this condition and treatment is based on symptoms.

Some recent studies have suggested that carriers of Bloom Syndrome may have a slightly increased risk for certain cancers including, but not limited to, breast cancer and colon cancer. However, other studies show no increased risk for cancer. The actual risk for cancer in carriers of Bloom Syndrome, if increased, is not clear and further studies need to be done.

What causes Bloom Syndrome?

Bloom Syndrome is caused by a gene change, or mutation, in both copies of the BLM gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of the BLM gene do not work correctly, it causes instability in the chromosomes (structures that contain genes), which leads to the health problems listed above.  

What is Canavan Disease?

Canavan Disease is an autosomal recessive disorder that causes abnormal muscle tone, developmental delay, and progressive intellectual disability. Hearing and vision loss may also occur.  Lifespan is decreased. Some children with Canavan Disease only live into early childhood while others will survive into their teens.  In rare cases, symptoms are less severe and typically include motor and speech delays and mild intellectual disability.Currently, there is no cure or specific treatment for this condition.

What causes Canavan Disease?

Canavan Disease is caused by a gene change, or mutation, in both copies of the ASPA gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the ASPA gene do not work correctly, it leads to the symptoms described above. 

What is Carbamoyl Phosphate Synthetase I Deficiency?

Carbamoyl Phosphate Synthetase I Deficiency (CPS) is an autosomal recessive disorder that causes a buildup of ammonia in the blood.  High ammonia levels can cause damage to the brain and nervous system. Signs and symptoms of the most common early-onset form often begin shortly after birth.  Symptoms may include sleepiness, poor appetite, breathing problems, vomiting, seizures, and unusual body movements.  If left untreated, some children have delayed development and intellectual disability.  Symptoms may occur after eating food high in protein, or during illness and can be life-threatening. Some people with this condition have a delayed-onset form that causes milder symptoms beginning later in life.  Children with this condition who have ongoing medical treatment and follow a special low-protein diet may be able to avoid some of the effects of this disorder. However, even with careful treatment, some children still have repeated episodes of high blood ammonia.   

What causes Carbamoyl Phosphate Synthetase I Deficiency?

Carbamoyl Phosphate Synthetase I Deficiency is caused by a gene change, or mutation, in both copies of the CPS1 gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of the CPS1 gene do not work correctly, it leads to the symptoms described above.

What is Carnitine Deficiency?

Carnitine Deficiency (also called Carnitine Uptake Defect, Primary Carnitine Deficiency, or Carnitine Transporter Deficiency) is an autosomal recessive disorder in which certain fats cannot be broken down and used for energy because the body cannot process carnitine. Carnitine is a substance that is found in food and helps the body turn fat into energy. Signs and symptoms of Carnitine Deficiency may begin shortly after birth or in childhood.  People with this condition may have low blood sugar (hypoglycemia), lack of energy, poor appetite, breathing problems, vomiting, diarrhoea, low blood sugar, and confusion.  Symptoms often appear during an illness or after going a long time without food and can be life-threatening if not treated.  Children with this disorder who do not receive treatment may develop an enlarged heart, muscle weakness, and liver disease.  Some people with Carnitine Deficiency never have symptoms of this condition. Treatment with carnitine can help prevent or reverse the signs and symptoms of Carnitine Deficiency. Children with this disorder who receive treatment can have healthy growth and development.

What causes Carnitine Deficiency?

Carnitine Deficiency is caused by a gene change, or mutation, in both copies of the SLC22A5 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the SLC22A5 gene do not work correctly, it leads to the symptoms described above.

What is Carnitine Palmitoyltransferase IA Deficiency?

Carnitine Palmitoyltransferase IA (CPT1A) Deficiency is an autosomal raecessive disorder in which the body is unable to break down certain fats for energy.  Symptoms of Carnitine Palmitoyltransferase IA Deficiency usually begin in infancy.  Children with Carnitine Palmitoyltransferase IA Deficiency can have lethargy (extreme tiredness), irritability, appetite problems, vomiting, diarrhoea, low blood sugar (hypoglycemia), seizures, and breathing problems.  Symptoms may appear after going a long time without eating or with illness and can be life-threatening.  Enlarged liver and muscle weakness sometimes also occur. Some children have milder symptoms and fewer health problems. Occasionally, the symptoms do not begin until adulthood and include just muscle cramping, pain, and weakness during exercise without the other symptoms. Lifelong dietary and medical treatment can help prevent or lessen the symptoms of Carnitine Palmitoyltransferase IA Deficiency.  With early diagnosis and careful treatment, children with Carnitine Palmitoyltransferase IA Deficiency often have healthy growth and development.

What causes Carnitine Palmitoyltransferase IA Deficiency?

Carnitine Palmitoyltransferase IA Deficiency is caused by a change, or mutation, in both copies of the CPT1A gene pair.  These mutations cause the genes to not work properly or not work at all. The CPT1A genes help the body break down a certain type of fat and change it into energy. When both copies of this gene do not work correctly, it can cause low blood sugar and the buildup of this fat in the liver, heart, and brain, leading to the symptoms

What is Carnitine Palmitoyltransferase II Deficiency?

Carnitine Palmitoyltransferase II (CPT II) Deficiency is an autosomal recessive disorder in which the body is unable to break down certain fats for energy.  Signs and symptoms of Carnitine Palmitoyltransferase II Deficiency begin in infancy, childhood, or in adulthood.   Infants with severe form can have abnormal development of the brain and kidneys, and life-threatening problems including breathing problems, low blood sugar (hypoglycemia), seizures, liver disease, and heart disease.  Affected children can have poor muscle tone (hypotonia), extreme tiredness, irritability, feeding problems, fever, diarrhea, vomiting and low blood sugar (hypoglycemia).  Other problems can include developmental delays, heart disease, liver disease, and seizures.  Symptoms may appear after going a long time without food or with illness and can be life-threatening.  Some affected individuals have a form that affects the muscles only, causing muscle pain and weakness. 

Lifelong dietary and medical treatment can help prevent some of the signs and symptoms of Carnitine Palmitoyltransferase II Deficiency.  With early diagnosis and careful treatment individuals with Carnitine Palmitoyltransferase II Deficiency can have healthy growth and development.

What causes Carnitine Palmitoyltransferase II Deficiency?

Carnitine Palmitoyltransferase II Deficiency is caused by a change, or mutation, in both copies of the CPT2 gene.  These mutations cause the genes to not work properly or not work at all.  The job of the CPT2 genes is to help the body break down a certain type of fat and change it into energy. When both copies of this gene do not work correctly, it can cause low blood sugar and the buildup of this fat in the liver, heart, and brain which leads to the symptoms described above.

What is Carpenter Syndrome?

Carpenter Syndrome is an inherited disorder that causes defects of the skull bones, hands, and feet as well as other parts of the body.  Children with Carpenter Syndrome are born with craniosynostosis (fused skull bones) which affects the shape of the head and the appearance of the face.  This can cause increased pressure in the skull and abnormal brain development if not corrected by surgery.  Children with Carpenter Syndrome often have shortened fingers and toes with webbing of the skin between them (syndactyly).  Some people with Carpenter Syndrome have mild to severe intellectual disabilities.  Other health problems happen sometimes and may include additional bone abnormalities, heart defects, vision and hearing problems, oral and dental abnormalities, obesity, and or genital abnormalities.  The signs and symptoms of Carpenter Syndrome vary among affected people.  

What causes Carpenter Syndrome?

Carpenter Syndrome is caused by a change, or mutation, in both copies of the RAB23 gene.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene pair do not work correctly, it causes the health problems described above.

What is Cartilage-Hair Hypoplasia?

Cartilage-Hair Hypoplasia (also known as Metaphyseal Dysplasia, Type McKusick) is an autosomal recessive disorder that affects the hair, bones, and digestive and immune systems.  Signs and symptoms include abnormally fine, sparse, brittle, light-coloured hair; bone abnormalities that lead to short stature due to short arms and legs (short-limbed dwarfism); constipation; problems digesting some nutrients and gluten from food; repeated infections; and increased risk for certain cancers (basal cell, leukaemia, and lymphoma). The immune system impairment varies from mild to severe. People with the most severe immune system problems have repeated and long-lasting infections that can be life-threatening. Some people also have other symptoms that may include light-coloured skin and abnormalities of the nails and teeth. 

Rarely, mutations in the same gene cause a related disorder, either Metaphyseal Dysplasia without Hypotrichosis or Anauxetic Dysplasia.  Metaphyseal Dysplasia without Hypotrichosis has similar bone symptoms and short stature as Cartilage-Hair Hypoplasia but does not cause hair abnormalities, immune system or digestive problems, or anaemia. Anauxetic Dysplasia causes more severe bone abnormalities and very short stature, distinct facial features, abnormalities of the teeth, and mild intellectual disability.  It is sometimes, but not always, possible to determine which of these disorders a specific mutation in the RMPR gene will cause. Currently, there is no cure for any of these conditions and treatment is based on the symptoms.

What causes Cartilage-Hair Hypoplasia?

Cartilage-Hair Hypoplasia is caused by a gene change, or mutation, in both copies of the RMRP gene pair.  These mutations cause the genes to not work properly or not work at all.   When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Cerebrotendinous Xanthomatosis?

Cerebrotendinous Xanthomatosis is an autosomal recessive lipid (fat) storage disorder.  People with this condition have difficulty breaking down different forms of cholesterol, causing these and other fats to build up in various parts of the body in the form of xanthomas.  Xanthomas are yellow, fatty nodules that are most often found in the brain and tendons of people with Cerebrotendinous Xanthomatosis.  It is important to treat this condition as symptoms can worsen over time due to the accumulation of excess fats throughout tissues in the body, although increased cholesterol levels are not found in the blood.  The number and severity of symptoms will vary from person to person so no two people with Cerebrotendinous Xanthomatosis will be affected the same, even within the same family.

Features of Cerebrotendinous Xanthomatosis can include chronic diarrhoea starting in infancy, clouding of the lens of the eye (cataracts) developing in late childhood, progressively brittle bones that are prone to break, and neurological problems in adulthood, such as dementia with decreasing intellectual abilities, seizures, hallucinations, depression, and difficulty with coordinating movements (ataxia) and speech (dysarthria).  The neurological symptoms that occur are thought to be related to the excess amounts of circulating fats and the xanthomas that develop in the brain.  Xanthomas that develop in tendons may cause discomfort and lessen tendon flexibility.  People with Cerebrotendinous Xanthomatosis also have an increased risk for heart disease. 

Currently, there is no cure for this condition; however, lifelong treatment with specific medications can either prevent or lessen some of the symptoms.

What causes Cerebrotendinous Xanthomatosis?

Cerebrotendinous Xanthomatosis is caused by a gene change, or mutation, in both copies of the CYP27A1 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Charcot-Marie-Tooth Disease with Deafness, X-Linked?

Charcot-Marie-Tooth Disease with Deafness, X-Linked (also known as Charcot-Marie-Tooth Neuropathy X, Type 1 or CMTX1) is a condition that occurs mainly in boys and causes progressive nerve damage. This nerve damage leads to muscle weakness, poor coordination and balance, numbness or lack of feeling to touch and vibration, and decreased ability to feel pain or temperature changes. As the disease progresses, people with Charcot-Marie-Tooth Disease with Deafness, X-Linked can have problems with muscle weakness in the limbs, coordination, walking, and speech. Weakness of the feet and ankles and a foot deformity known as pes cavus (high arched foot) is common. Hearing loss occurs in some individuals. A small number of individuals need a wheelchair in adulthood. Symptoms typically begin between early childhood and adulthood and develop slowly over time. Intelligence and lifespan are normal. Female carriers may develop symptoms; however, they are typically milder than those seen in males.

What causes Charcot-Marie-Tooth Disease with Deafness, X-Linked?

Charcot-Marie-Tooth Disease with Deafness, X-Linked is caused by a change, or mutation, in the GJB1 gene.  When the GJB1 gene is not working properly it can lead to the symptoms described above. CMTX1 is an X-linked condition, meaning it is caused by a mutation (change) in the GJB1 gene on the X chromosome. Females have two copies of the X chromosome, but males only have one copy. If a boy has a mutation in his GJB1 gene, he will be affected with CMTX1. A girl who has a mutation in the GJB1 gene on one of her X chromosomes is a carrier of CMTX1, and may or may not have some symptoms which, if present, are typically milder. CMTX1 is usually inherited from a mother who is a carrier of a mutation in the GJB1 gene.  

What is Charcot-Marie-Tooth Disease, Type 4D?

Charcot-Marie-Tooth Disease, Type 4D (CMT4D) is an autosomal recessive disorder that causes damage to the peripheral nerves (the nerves outside the brain and spinal cord).  Signs of the condition usually begin in childhood and worsen with age. Symptoms include deafness and loss of feeling and muscle wasting in the legs, hands, and feet. The hearing loss may begin in childhood but more commonly starts in adulthood. As the disease progresses, people with this condition often have problems with muscle weakness, coordination, walking, and speech. A high arched foot, known as pes cavus, is common. Some people need a wheelchair in adulthood.  CMT4D does not cause intellectual disability and lifespan is usually normal. Currently, there is no cure for CMT4D and treatment is based on symptoms.

What causes Charcot-Marie-Tooth Disease, Type 4D?

Charcot-Marie-Tooth Disease, Type 4D is caused by a gene change, or mutation, in both copies of the NDRG1 gene.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it causes the symptoms described above.

What is Choreoacanthocytosis?

Choreoacanthocytosis (also known as Chorea-Acanthocytosis) is an autosomal recessive disorder that causes neurological problems and abnormally shaped red blood cells.  People with this disorder have involuntary jerking movements (chorea) and muscle spasms (dystonia) that worsen over time. The chorea and dystonia occur mainly in the muscles of the limbs, face, mouth, tongue, and throat. Abnormal red blood cells shaped like stars (acanthocytosis) are also common. Seizures develop in about half of all people with this condition and changes in behaviour and loss of memory often occur as the condition progresses. People with Choreoacanthocytosis usually start showing symptoms around the age of 30, although symptoms can start as early as age 10 or as late as age 70.  There is currently no cure for Choreoacanthocytosis and lifespan is reduced.

What causes Choreoacanthocytosis?

Choreoacanthocytosis is caused by a gene change, or mutation, in both copies of the VPS13A gene. These mutations cause the genes to not work properly or not work at all.  When both copies of this gene pair do not work correctly, it causes the symptoms described above.

What is Choroideremia?

Choroideremia is an X-linked inherited condition that causes progressive vision loss, mainly in boys and men. The first sign of Choroideremia is typically loss of night vision.  This can sometimes occur during childhood but usually begins in the teens.  Loss of peripheral vision (ability to see things on the side when looking straight ahead) follows night blindness and eventually leads to complete blindness in late adulthood. 

What causes Choroideremia?

Choroideremia is caused by a change, or mutation, in the CHM gene. This mutation causes the gene to not work properly or not work at all.   When the CHM gene in a male is not working correctly, it leads to the symptoms described above. Females who are carriers for Choroideremia typically do not have any symptoms; however, rare female carriers have been reported with mild adult-onset vision changes.

What is Chronic Granulomatous Disease, CYBA-Related?

Chronic Granulomatous Disease, CYBA-Related (also called Chronic Granulomatous Disease, Cytochrome b-negative) is an autosomal recessive disorder that affects the immune system and reduces the body’s ability to fight infection. The immune system is unable to kill bacteria, fungi, and yeast infections and, instead, the immune cells in the body form walls around the infections, forming ‘knots’ called granulomas and chronic inflammation. The lungs are the most commonplace for infections but they can also occur in the lymph nodes, liver, bladder, bone, skin, and intestines. Individuals with this condition are also at increased risk for autoimmune diseases. Symptoms can begin anytime between infancy to adulthood but most will have symptoms before the age of five. Long-term use of medication is often needed to treat infections and reduce inflammation. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Chronic Granulomatous Disease, CYBA-Related?

Chronic Granulomatous Disease, CYBA-Related is caused by a gene change, or mutation, in both copies of the CYBA gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Chronic Granulomatous Disease, X-Linked?

Chronic Granulomatous Disease, X-Linked is an X-linked inherited disorder that decreases the body’s ability to fight infection. The disorder affects mostly males and female carriers usually do not have symptoms. With Chronic Granulomatous Disease, X-Linked, the body is unable to kill bacteria and fungi which then cause infections and inflammation (swelling). The immune cells in the body form a wall around bacteria and infection, forming “knots” called granulomas. Repeated infections occur and often develop in the lungs, lymph nodes, liver, bones, skin, bladder, and gastrointestinal system. Diseases caused by inflammation, such as colitis, bladder and kidney problems happen even when there is no infection present. Symptoms can begin anytime between infancy to adulthood; however most will have symptoms before the age of five. Finding the type of infection and treating it immediately is very important.  Medications are often needed to treat infections. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Chronic Granulomatous Disease, X-Linked?

Chronic Granulomatous Disease, X-Linked is caused by a change, or mutation, in the CYBB gene.  The role of the CYBB gene is to make a protein that is important for immune system. When the CYBB gene is not working properly in a male it leads to the symptoms described above. Female carriers do not typically have symptoms of the disorder, although rare carriers may show mild symptoms.

What is Ciliopathies, RPGRIP1L-Related?

Ciliopathies, RPGRIP1L-Related refers to a group of autosomal recessive disorders that cause abnormalities of the cilia, the hair-like structures on the outside of many body cells that help with sensing what’s happening around them and, in some areas of the body, helping move substances like mucus.  The group of Ciliopathies, RPGRIP1L-Related include the following disorders: Joubert Syndrome Type 7; Meckel Syndrome Type 5; and COACH Syndrome.

Joubert Syndrome Type 7 has signs and symptoms that begin in infancy and affect the brain and kidneys and include abnormalities of the cerebellum of the brain, developmental delay, intellectual disability, ataxia (gait problems), poor muscle tone (hypotonia), breathing problems, abnormal eye movements, and kidney disease. Lifespan is often shortened.  Meckel Syndrome Type 5 causes multiple birth defects including encephalocele (protrusion of the brain through the skull), cleft lip and palate, cystic kidneys, extra fingers and toes, and other problems. Some infants are born with anencephaly, a severe lethal brain defect where parts of the brain and skull do not develop. Meckel Syndrome often leads to death in infancy.  Symptoms of COACH Syndrome are similar to Joubert Syndrome Type 7, but with a liver disease called hepatic fibrosis. Currently, there is no cure for these conditions and treatment is based on symptoms.

What causes Ciliopathies, RPGRIP1L-Related?

Ciliopathies, RPGRIP1L-Related are caused by a gene change, or mutation, in both copies of the RPGRIP1L gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms of one of the disorders described above. It is sometimes, but not always, possible to determine which specific disease in the group of Ciliopathies, RPGRIP1L-Related a specific mutation in the RPGRIP1L gene is likely to cause.

What is Citrin Deficiency?

Citrin Deficiency, also known as Citrullinemia type II, is an autosomal recessive disorder with symptoms that begin either in infancy or later in adolescence or adulthood.  Affected infants can have jaundice (yellow skin and eyes), growth delay, liver disease, and hypoglycemia (low blood sugar). Symptoms may appear after going a long time without food or during illness. These symptoms often resolve by 6 to 12 months of age. However, some affected infants will have continued problems that may include liver cirrhosis and severe infections later in life. Adult-onset Citrin Deficiency symptoms include sudden onset of disorientation, abnormal behaviour, seizures, liver disease, and coma due to high blood ammonia levels. Treatment often includes a low carbohydrate diet and certain supplements. If the condition is not treated, a liver transplant may be needed.

What causes Citrin Deficiency?

Citrin Deficiency is caused by a gene change, or mutation, in both copies of the SLC25A13 gene pair. These mutations cause the genes to not work properly or not work at all. The SLC25A13 genes provide instructions for making a protein called citrin, which is important in many parts of the body.  When both copies of this gene pair do not work correctly, it causes the symptoms described above. 

What is Citrullinemia, Type 1?

Citrullinemia, Type 1 is an autosomal recessive disorder in which the body is unable to remove certain waste products, specifically ammonia, which leads to a toxic buildup in the body.  There are several types of Citrullinemia, Type 1.  In the severe form, life-threatening problems begin in the first days of life with lethargy, poor feeding, vomiting, seizures, and coma.  Some people have a later-onset (childhood or adulthood) type Citrullinemia, Type 1 with symptoms that include headaches, vision loss, problems with balance and muscle coordination (ataxia), and lethargy (extreme tiredness).  Some people with Citrullinemia, Type 1 never experience signs and symptoms of the disorder.  Treatment includes lifelong dietary and medical management. 

What causes Citrullinemia, Type 1?

Citrullinemia, Type 1 is caused by a gene change, or mutation, in both copies of the ASS1 gene pair.  These mutations cause the genes to not work properly or not work at all.  The function of the ASS1 genes is to break down specific toxins in the body.  When both copies of this gene do not work correctly, it causes a buildup of toxins, including ammonia, which leads to the symptoms described above.

What is Cohen Syndrome?

Cohen Syndrome is an autosomal recessive disorder that affects many parts of the body. Signs and symptoms begin in infancy and include developmental delay, small head size, a distinctive facial appearance, and hypotonia (low muscle tone).  Affected children have intellectual disability, vision problems, overly mobile joints, obesity, short stature, narrow hands and feet, and neutropenia (low level of white blood cells). Currently, there is no cure for Cohen Syndrome and treatment is based on symptoms.

What causes Cohen Syndrome?

Cohen Syndrome is caused by a gene change, or mutation, in both copies of the VPS13B gene pair (also known as COH1).  These mutations cause the genes to not work properly or not work at all. When both copies of the VPS13B gene pair do not work correctly, it leads to the symptoms described above. 

What is Combined Malonic and Methylmalonic Aciduria?

Combined Malonic and Methylmalonic Aciduria is an autosomal recessive disorder that causes high levels of malonic acid and methylmalonic acid in the body and urine.  Signs and symptoms can begin in childhood or adulthood.  In those with the childhood-onset disease, symptoms may include organ damage due to acidosis, involuntary muscles tension, weak muscle tone, developmental delays, poor growth and weight gain, small head size, low blood sugar, or even coma.  For those with the delayed adult-onset disease, symptoms usually include seizures, memory loss, cognitive decline, or psychiatric disease.

What causes Combined Malonic and Methylmalonic Aciduria?

Combined Malonic and Methylmalonic Aciduria is caused by a change, or mutation, in both copies of the ACSF3 gene pair.  These mutations cause the ACSF3 genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Combined Oxidative Phosphorylation Deficiency 1?

Combined Oxidative Phosphorylation Deficiency 1 is a severe autosomal recessive disorder that begins before birth and affects many parts of the body including the brain, nervous system, heart, and liver. Symptoms in affected infants include growth delay, small head size, brain abnormalities, tight muscles, decreased movements, seizures, developmental delay, and poor muscle tone. Affected infants also develop cardiomyopathy (an enlarged heart that does not pump properly), and liver disease. Symptoms progressively worsen and death often occurs in infancy or in the first few years of life. Currently, there is no cure for this condition.

What causes Combined Oxidative Phosphorylation Deficiency 1?

Combined Oxidative Phosphorylation Deficiency 1 is caused by a change, or mutation, in both copies of the GFM1 gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of the GFM1 gene pair do not work correctly, it leads to the symptoms described above.

What is Combined Oxidative Phosphorylation Deficiency 3?

Combined Oxidative Phosphorylation Deficiency 3 is an autosomal recessive disorder that affects the mitochondria, the energy-producing parts of the cells.  This condition affects many parts of the body including the brain, nervous system, heart, and liver.  Signs and symptoms usually begin before or at birth.  Infants typically have a slower than average growth rate, brain abnormalities, tight muscles (spasticity), abnormal movements, seizures, developmental delay, muscle weakness, and poor muscle tone.  Many infants also have episodes of metabolic acidosis in which toxic substances build up in the blood and cause lack of energy, vomiting, breathing problems, seizures, and sometimes coma or death.  Some infants also develop an enlarged heart (cardiomyopathy) and enlarged liver.  Children with the severe form of this condition often die in infancy or early childhood.  Some children with Combined Oxidative Phosphorylation Deficiency 3 have a milder form of the condition with symptoms that show up later that may include learning disabilities or intellectual disability, vision loss, muscle weakness, and a movement disorder.  Currently, there is no cure or specific treatment for this condition.

What causes Combined Oxidative Phosphorylation Deficiency 3?

Combined Oxidative Phosphorylation Deficiency 3 is caused by a gene change, or mutation, in both copies of the TSFM gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work properly, it leads to the symptoms described above.

What is Combined Pituitary Hormone Deficiency-2?

Combined Pituitary Hormone Deficiency-2 is an autosomal recessive disorder that causes short stature and other health and developmental problems.  These symptoms are caused by a lack of pituitary hormones in the body.  Pituitary hormones are made in the brain by the pituitary gland.  Affected infants have low blood sugar (hypoglycemia), seizures (due to hypoglycemia), and growth delay.  Hypothyroidism and cortisol deficiency can also occur.  Without treatment affected, individuals have short stature and may have delayed or absent puberty and infertility (inability to have biological children).  Treatment includes lifelong pituitary hormone replacement therapy.  With treatment, affected individuals can lead healthy lives. 

What causes Combined Pituitary Hormone Deficiency-2?

Combined Pituitary Hormone Deficiency-2 is caused by a change, or mutation, in both copies of the PROP1 gene pair.  These mutations cause the genes to not work properly or not work at all.  The PROP1 genes are important in the development of the pituitary gland. When both copies of this gene do not work correctly, the pituitary gland is unable to make the hormones that are important for growth and onset of puberty, leading to the symptoms described above.

What is Congenital Adrenal Hyperplasia, 17-Alpha-Hydroxylase Deficiency?

Congenital Adrenal Hyperplasia, 17-Alpha-Hydroxylase Deficiency is an autosomal recessive disorder that causes decreased production of sex hormones in the body.  Affected males are born with external genitals that do not have the typical appearance of male or female (ambiguous genitalia) and without treatment, they will not go through normal puberty. Affected females are born with normal external genitals but without treatment, they will not go through normal puberty or develop secondary sexual characteristics.  Both males and females with this disorder have hypertension (high blood pressure) and low potassium levels. Treatment includes hormone replacement therapies. 

What causes Congenital Adrenal Hyperplasia, 17-Alpha-Hydroxylase Deficiency?

Congenital Adrenal Hyperplasia, 17-Alpha-Hydroxylase Deficiency is caused by a change, or mutation, in both copies of the CYP17A1 gene pair.  These mutations cause the genes to not work properly or not work at all.  The function of the CYP17A1 genes is to help make sex hormones and other hormones.  When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Congenital Amegakaryocytic Thrombocytopenia?

Congenital Amegakaryocytic Thrombocytopenia is a rare autosomal recessive disorder that leads to a reduced number of certain blood cells (megakaryocytes) that make platelets, which are needed for blood clotting.  This can progress to bone marrow failure over time. Symptoms are usually seen within the first week to nine months of life and include bleeding in the lung, intestines, brain, and skin. Some children also have delayed development and or heart defects. Treatment includes repeated blood transfusions. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual. If Congenital Amegakaryocytic Thrombocytopenia is left untreated, about a third of patients die of bleeding complications or bone marrow failure.

What causes Congenital Amegakaryocytic Thrombocytopenia?

Congenital Amegakaryocytic Thrombocytopenia is caused by a gene change, or mutation, in both copies of the MPL gene.  These mutations cause the genes to not work properly or not work at all.  When both copies of the MPL gene do not work correctly, it causes the symptoms described above.

What is Congenital Disorder of Glycosylation, Type 1A, PMM2-Related?

Congenital Disorder of Glycosylation, Type 1A, PMM2-Related, also known as PMM2-Congenital Disorder of Glycosylation, is an autosomal recessive disorder that affects many parts of the body.  Signs and symptoms usually begin in infancy and include weak muscle tone, inverted nipples, abnormal distribution of fat, eyes that do not look in the same direction (strabismus), distinct facial features, developmental delay, and a failure to grow or gain weight.  Children with Congenital Disorder of Glycosylation, Type 1A, PMM2-Related may also have an underdeveloped area of the brain, called the cerebellum, which controls and coordinates body movement.  Children with this disorder may also have elevated liver function tests, seizures, fluid around the heart, and blood clotting disorders.  The symptoms of this condition can be life-threatening and about 20% of affected infants die within the first year of life.  Affected individuals may develop a moderate intellectual disability in childhood and some are unable to walk independently; some may also experience stroke-like episodes.  Teenagers and adults with Congenital Disorder of Glycosylation, Type 1A, PMM2-Related may have reduced sensation and weakness in their arms and legs, an abnormal curvature of the spine, impaired muscle coordination, and joint deformities.  Some affected individuals experience significant vision loss.  Females with Congenital Disorder of Glycosylation, Type 1A, PMM2-Related typically do not go through puberty. Currently, there is no cure for this disorder and treatment is based on symptoms.

What causes Congenital Disorder of Glycosylation, Type 1A, PMM2-Related?

Congenital Disorder of Glycosylation, Type 1A, PMM2-Related is caused by a change, or mutation, in both copies of the PMM2 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Congenital Disorder of Glycosylation, Type 1B?

Congenital Disorder of Glycosylation, Type 1B is an autosomal recessive disorder that causes problems with the growth and function of the body.  Symptoms begin in infancy and include failure to gain weight and slower than average growth (failure to thrive).  Affected children can have poor muscle tone (hypotonia), digestive problems, malnutrition, liver disease, increased number of infections, low blood sugar, and problems forming blood clots. Treatment can be successful in reversing symptoms.  Lack of treatment may result in death.  Intellectual disability and neurologic problems are not present in Congenital Disorder of Glycosylation, Type 1B in contrast to other types of Congenital Disorders of Glycosylation. 

What causes Congenital Disorder of Glycosylation, Type 1B?

Congenital Disorder of Glycosylation, Type 1B is caused by a gene change, or mutation, in both copies of the MPI gene. These mutations cause the genes to not work properly or not work at all. The function of the MPI genes is to help process fats and proteins from the diet so that they can be used in the body.  When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Congenital Disorder of Glycosylation, Type 1C?

Congenital Disorder of Glycosylation, Type 1C, also known as ALG6-Congenital Disorder of Glycosylation, is an autosomal recessive disorder that causes problems with the growth and function of the body.  Symptoms begin in infancy and include failure to gain weight and slower than average growth (failure to thrive).  Affected children can have neurologic problems including poor muscle tone (hypotonia), developmental delay, problems with balance and movement (ataxia), seizures, and in some cases, stroke-like episodes. Vision problems, including strabismus (lazy eye) and a vision loss condition called retinitis pigmentosa, can also occur in Congenital Disorder of Glycosylation, Type 1C.  Affected females often have low levels of sex hormones and may not go through puberty without hormone replacement therapy.

What causes Congenital Disorder of Glycosylation, Type 1C?

Congenital Disorder of Glycosylation, Type 1C is caused by a gene change, or mutation, in both copies of the ALG6 gene. These mutations cause the genes to not work properly or not work at all. The function of the ALG6 genes is to help process fats and proteins from the diet so that they can be used in the body.  When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Congenital Finnish Nephrosis?

Congenital Finnish Nephrosis, also known as Congenital Nephrotic Syndrome or Nephrotic Syndrome Type 1, is an autosomal recessive disorder that affects the kidneys. Symptoms often begin before birth and may include a large placenta and premature birth. Affected babies often have swelling of the body (edema), high cholesterol, anemia, and repeated infections. The kidneys become more damaged over time which leads to blood and/or too much protein being lost in the urine. In most cases the kidney disease progresses to complete renal failure within the first 10 years of life. Without a kidney transplant affected individuals often die in childhood or early adulthood.

What causes Congenital Finnish Nephrosis?

Congenital Finnish Nephrosis is caused by a gene change, or mutation in both copies of the NPHS1 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the NPHS1 gene do not work correctly, it leads to the kidney damage and symptoms described above.

What is Congenital Hyperinsulinism, KCNJ11-Related?

Congenital Hyperinsulinism, KCNJ11-Relatead (also called Hyperinsulinemic Hypoglycemia) is an autosomal recessive disorder that causes abnormally high levels of insulin, the hormone that controls blood sugar. This leads to episodes of low blood sugar (hypoglycemia), usually starting the first few days or months of life. Low blood sugar causes lack of energy, irritability, and poor feeding. If left untreated it may lead to seizures and brain damage. Symptoms also include poor muscle tone and breathing problems. Treatment with special diet and medications may help reduce the symptoms, but some children may need surgery to remove all or part of the pancreas. If not treated, this condition can cause intellectual disability.

What causes Congenital Hyperinsulinism, KCNJ11-Related?

Congenital Hyperinsulinism, KCNJ11-Related is caused by a gene change, or mutation, in both copies of the KCNJ11 gene pair. These mutations cause the KCNJ11 genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

Less commonly, mutations in the same gene cause a different disorder, either Permanent Neonatal Diabetes Mellitus or Transient Neonatal Diabetes Mellitus. Babies with these conditions have low birth weight and high blood sugar (hyperglycemia), dehydration and growth failure within the first 6 months of life. Transient Neonatal Diabetes Mellitus typically resolves before age 2 but often returns again in the teens or early adulthood. Permanent Neonatal Diabetes Mellitus needs lifelong treatment. Some children with Permanent Neonatal Diabetes Mellitus also have developmental delay, seizures, or learning problems. Neonatal Diabetes Mellitus is usually inherited in and autosomal dominant manner from a parent who is affected with the disorder. It is sometimes, but not always, possible to determine whether a specific mutation in the KCNJ11 gene will cause Congenital Hyperinsulinism, KCNJ11-Related or Neonatal Diabetes Mellitus.

What is Congenital Insensitivity to Pain with Anhidrosis (CIPA)?

Congenital Insensitivity to Pain with Anhidrosis (CIPA) is an autosomal recessive disorder that affects the nervous system. People with this disorder cannot feel pain or temperature changes, have reduced or absent sweating (anhidrosis), and most have some degree of intellectual disability.  Signs and symptoms of CIPA usually begin at birth or shortly after and, because of repeated injuries and burns that cannot be felt, the condition is life-threatening. High fevers are common and can lead to seizures if not treated. Other symptoms may include slow healing of wounds and broken bones, thickened skin, and patchy hair loss.  About half of all people with this condition have emotional and behavioral problems that may include anxiety and severe attention deficit hyperactivity disorder (ADHD).  Currently there is no cure for this condition, but with supportive treatment people with CIPA can live into adulthood.

What causes Congenital Insensitivity to Pain with Anhidrosis (CIPA)?

Congenital Insensitivity to Pain with Anhidrosis is caused by a gene change, or mutation, in both copies of the NTRK1 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Congenital Myasthenic Syndrome, CHRNE-Related?

Congenital Myasthenic Syndrome, CHRNE-Related is an inherited disorder that affects the muscles and is usually autosomal recessive but, in some late-onset cases, is autosomal dominant.  Symptoms of muscle weakness (myasthenia) can begin after birth but may begin later in life.  Affected infants and children often have feeding and swallowing problems, developmental delay, and at times may have breathing problems.  Muscle weakness can worsen with exercise.  Speech problems may occur due to facial muscle weakness.  The weakness remains stable and does not worsen with age.  The degree of muscle weakness varies among individuals affected with Congenital Myasthenic Syndrome, CHRNE-Related.  Some individuals have later onset of symptoms that may include weakness of the neck, wrist, and fingers along with progressive breathing problems. 

What causes Congenital Myasthenic Syndrome, CHRNE-Related?

Most cases of Congenital Myasthenic Syndrome, CHRNE-Related are caused by a change, or mutation, in both copies of the CHRNE gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of the CHRNE gene do not work correctly, the signals from the nerves to the muscles are disrupted, causing problems with movement of skeletal muscles, muscle weakness, and delayed development of motor skills.

Some cases of late-onset Congenital Myasthenic Syndrome, CHRNE-Related are inherited in an autosomal dominant manner.  This means that a person who has a mutation in just one copy of the CHRNE gene will have symptoms of the late-onset form of this condition. 

What is Congenital Myasthenic Syndrome, RAPSN-Related?

Congenital Myasthenic Syndrome, RAPSN-Related is an autosomal recessive disorder that causes muscle weakness that becomes worse during physical exercise. The first symptoms of this disorder usually appear shortly after birth. Occasionally, symptoms may not appear until late childhood, adolescence, or adulthood. The symptoms vary from person to person but the muscles of the face are almost always affected.  This causes problems with holding up the head, opening and closing the eyes, chewing, and swallowing. Most children with this disorder have problems eating, delayed crawling and walking, and poor coordination.  Some children with this condition have more severe muscle weakness and cannot walk.  Breathing problems, especially during illness, happen in some children.   

What causes Congenital Myasthenic Syndrome, RAPSN-Related?

Congenital Myasthenic Syndrome, RAPSN-Related is caused by a gene change, or mutation, in both copies of the RAPSN gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Congenital Neutropenia, HAX1-Related?

Congenital Neutropenia, HAX1-Related is an autosomal recessive disorder that causes low levels of immune cells called neutrophils (a type of white blood cell).  This causes problems with immune system function.  Affected individuals have symptoms beginning in infancy with frequent bacterial infections.  Over time, there is an increased risk of developing blood cancers. In addition, some affected children have intellectual disability, developmental delay, and seizures.  Early death due to infection may occur in some children. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Congenital Neutropenia, HAX1-Related?

Congenital Neutropenia, HAX1-Related is caused by a gene change, or mutation, in both copies of the HAX1 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the HAX1 gene do not work correctly, it causes early death of neutrophils, leading to low levels in the bloodstream. This leads to the symptoms described above. 

What is Congenital Neutropenia, VPS45-Related?

Congenital Neutropenia, VPS45-Related is an autosomal recessive disorder that causes low levels of immune cells called neutrophils (a type of white blood cell). This causes problems with immune system function.  Affected individuals have symptoms beginning in infancy with frequent bacterial infections.  Over time, there is an increased risk of developing blood cancers. In addition, some affected children have developmental delay.  Early death due to infection may occur in some children. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Congenital Neutropenia, VPS45-Related?

Congenital Neutropenia, VPS45-Related is caused by a gene change, or mutation, in both copies of the VPS45 gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of the VPS45 gene do not work correctly, the neutrophils that are produced either do not function properly or die off prematurely, leading to low levels in the bloodstream.  This causes the symptoms described above. 

What is Corneal Dystrophy and Perceptive Deafness?

Corneal Dystrophy and Perceptive Deafness is an autosomal recessive disorder that causes eye abnormalities and vision and hearing loss. Symptoms usually begin in later childhood or adulthood. The eye problems involve worsening buildup of substances in the cornea (outer layer) of the eye, leading to vision loss.  Hearing loss usually begins in childhood and worsens with age.  Corneal Dystrophy and Perceptive Deafness is also called Harboyan Syndrome.

A different form of this condition, called Corneal Dystrophy, Endothelial 2 is caused by changes in the same gene and has symptoms that are present at birth.  Corneal Dystrophy, Endothelial 2 causes thickening and clouding of the cornea leading to blurred vision and nystagmus (rapid, jittery eye movements) and sometimes causes hearing loss. Currently there is no cure for these conditions and treatment is based on symptoms.

What causes Corneal Dystrophy and Perceptive Deafness?

Both Corneal Dystrophy and Perceptive Deafness and Corneal Dystrophy, Endothelial 2 are caused by a gene change, or mutation, in both copies of the SLC4A11 gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of the gene do not work correctly, it leads to either Corneal Dystrophy and Perceptive Deafness or Corneal Dystrophy, Endothelial 2 . 

What is Corticosterone Methyloxidase Deficiency?

Corticosterone Methyloxidase Deficiency, also called Aldosterone Synthase Deficiency, is an autosomal recessive disorder that causes too much sodium to be excreted in the urine. This leads to decreased levels of sodium and increased levels of potassium in the blood. Symptoms begin shortly after birth and include poor feeding, nausea, vomiting, fatigue, low blood pressure, muscle weakness, and dehydration. Severe forms of this disorder may lead to metabolic acidosis, where the blood becomes too acidic. Metabolic acidosis can cause seizures and coma, which may be life-threatening. This condition is treated with hormone replacement therapy. Most people with this condition who survive the newborn period have mild or no symptoms in adulthood. 

Very rarely a specific mutation in the same gene causes a separate disorder called Familial Hyperaldosteronism which is inherited in an autosomal dominant manner.  In this disorder, the body makes too much aldosterone, a hormone made by the adrenal gland, which causes severe high blood pressure (hypertension).  If not treated, there is an increased risk for stroke, heart disease, and kidney failure.  It is usually possible to tell whether a specific gene mutation will cause Corticosterone Methyloxidase Deficiency or Familial Hyperaldosteronism.

What causes Corticosterone Methyloxidase Deficiency?

Corticosterone Methyloxidase Deficiency is caused by a gene change, or mutation, in both copies of the CYP11B2 gene pair.  These mutations cause the genes to not work properly or not work at all.  Normal function of the CYP11B2 gene pair is needed to make a hormone called aldosterone which regulates salt balance in the body. When both copies of the CYP11B2 gene do not work correctly, it leads to the symptoms described above.

Familial Hyperaldosteronism (FH) is autosomal dominant.  A person with an FH-causing mutation in one copy of the CYP11B2 gene pair is affected with the disorder.

What is Costeff Syndrome (3-Methylglutaconic Aciduria, Type 3)?

Costeff Syndrome (also known as 3-Methylglutaconic Aciduria, Type 3) is an autosomal recessive disorder that causes vision loss, jerky movements called chorea, muscle stiffness and, in some people, mild intellectual disability. Vision loss caused by breakdown, or atrophy, of the optic nerve often starts in childhood and worsens over time. Problems with muscle control and movement start later in childhood and worsen over time, sometimes leading to wheelchair use. High levels of 3-methylglutaconic acid are found in the urine of people with this condition. This does not cause the health problems seen in Costeff Syndrome but can help diagnose the condition. Currently there is no cure for this disorder and treatment is based on symptoms.

What causes Costeff Syndrome?

Costeff Syndrome is caused by a gene change, or mutation, in both copies of the OPA3 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the OPA3 gene do not work correctly, it leads to the symptoms described above. 

Very rarely, a mutation in the same gene causes a related disorder called Autosomal Dominant Optic Atrophy and Cataract. People with this disorder have progressive vision loss in both eyes due to atrophy of the optic nerves and clouding of the lens of the eye. The vision loss can start in childhood or early adulthood.

What are CRB1-Related Retinal Dystrophies?

CRB1-Related Retinal Dystrophies are a group of autosomal recessive inherited disorders that include Leber Congenital Amaurosis-8; Retinitis Pigmentosa-12, Autosomal Recessive; and Cone-Rod Dystrophy.  Leber Congenital Amaurosis-8 causes severe vision loss that is either present at birth or begins in early childhood and progresses to complete vision loss over time.  Other symptoms of Leber Congenital Amaurosis-8 may include light sensitivity (photophobia), abnormal eye movements (nystagmus), cataracts, and thinning of the cornea (covering of the eye).  Retinitis Pigmentosa-12 causes loss of vision that often starts in childhood, and rarely not until adolescence, and worsens over time but does not cause other symptoms. Cone-Rod Dystrophy causes vision loss that progresses over time with the first symptoms usually including loss of sharpness to the vision, lessened color vision, loss of central vision, and photophobia. Night blindness, loss of peripheral vision, and nystagmus then occur over time. Currently there is no cure for the CRB1-Related Retinal Dystrophies and treatment is based on symptoms.

What causes CRB1-Related Retinal Dystrophies?

The CRB1-Related Retinal Dystrophies are caused by a gene change, or mutation, in both copies of the CRB1 gene pair.  These mutations cause the genes to not work properly or not work at all. The CRB1 genes make a protein that is important for the normal development of light-sensing cells in the retina of the eye called photoreceptors. When both copies of the CRB1 gene do not work correctly, vision loss occurs. 

What is Creatine Transporter Defect (Cerebral Creatine Deficiency Syndrome 1, X-Linked)?

Creatine Transporter Defect (also known as Cerebral Creatine Deficiency Syndrome 1 or X-linked Creatine Deficiency) is an X-linked disorder that affects mainly males and causes intellectual disability, behavior problems, seizures, and muscle weakness. Affected males have symptoms beginning in infancy that include small head size, development and growth delays, characteristic facial features, digestive problems, and poor muscle tone. Currently there is no cure for this condition and treatment is based on symptoms. Female carriers of Creatine Transporter Defect may have some degree of intellectual disability and behavior problems.

What causes Creatine Transporter Defect?

Creatine Transporter Defect is caused by a change, or mutation, in the SLC6A8 gene. This mutation causes the gene to not work properly or not work at all. People with this disorder do not make a protein needed to allow creatine, a substance that is required for the body to store and use energy, into a cell. Parts of the body that require a lot of energy, such as the brain, are affected when there is not enough creatine available.  

What is Cystic Fibrosis?

Cystic Fibrosis is an autosomal recessive disorder that affects many different areas of the body including the lungs, digestive system, and fertility.  Cystic Fibrosis does not affect intelligence.  Signs and symptoms of Cystic Fibrosis start in early childhood and include delayed growth caused by problems in digestion and repeated lung infections that lead to permanent lung damage. Children and adults with Cystic Fibrosis usually have frequent hospitalizations because of lung infections.  Over time, complications of Cystic Fibrosis can lead to lung transplants and early death.  There are treatments for Cystic Fibrosis that can lessen the severity of the symptoms; however, there is currently no cure.  

What causes Cystic Fibrosis?

Cystic Fibrosis is caused by a change, or mutation, in both copies of the CFTR gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, mucus and other body fluids become thick and sticky. This causes problems with how the lungs, digestive system, and other body systems function and leads to the symptoms described above.   

Although most CFTR gene mutations cause classic CF, there are some specific CFTR mutations that cause less severe symptoms, and some only affect male fertility. A small number of CF carriers may have mild respiratory or other symptoms.

What is Cystinosis?

Cystinosis is an autosomal recessive disorder that causes the amino acid cysteine, one of the building blocks of protein, to build up in cells of the body.  The excess cysteine forms crystals which can damage tissues and organs in the body. Damage to the kidneys and eyes occurs most often, but damage to the muscles, thyroid, pancreas, and testes may also occur. There are three forms of Cystinosis that have symptoms which range from mild to severe. The most severe form, called Nephropathic Cystinosis, starts shortly after birth. Symptoms include poor growth and a kidney disorder that leads to loss of minerals and nutrients in the urine. Cysteine crystals also build up in the eyes, causing sensitivity to light, eye pain, and vision loss. Symptoms also include loss of muscle mass, difficulty swallowing, diabetes, thyroid and nervous system problems. The childhood-onset form starts later but shows the same type of symptoms. There is also a milder form that causes eye problems but usually does not cause kidney damage. Medical treatment can lessen or delay some of symptoms of Cystinosis.  Without treatment, children with Cystinosis may develop kidney failure by age 10 and need a kidney transplant. 

What causes Cystinosis?

Cystinosis is caused by a gene change, or mutation, in both copies of the CTNS gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is D-Bifunctional Protein Deficiency?

D-Bifunctional Protein Deficiency is an autosomal recessive disorder in which the body cannot break down certain building blocks of fat called ‘fatty acids’.  This leads to the buildup of fatty acids in the blood and organs that then cause damage to many parts of the body, especially the brain and nervous system.  Signs and symptoms begin in infancy and include large head size, distinct facial features, feeding problems, poor muscle tone, vision and hearing loss, liver and kidney disease, seizures, severe developmental delay, and bone abnormalities.  There is no cure for this disorder and death usually occurs before two years of age.  Rarely, a child with this condition may start having symptoms at a later age leading to loss of skills and death later in childhood. Very rarely, mutations in the same gene cause a different disorder called Perrault Syndrome.  Symptoms of Perrault Syndrome include hearing loss starting at birth or early childhood that worsens over time and, in females, missing or non-working ovaries with infertility. Some people with this condition also have learning difficulties, problems with coordination and walking, and loss of sensation in the arms and legs. 

What causes D-Bifunctional Protein Deficiency?

D-Bifunctional Protein Deficiency is caused by a gene change, or mutation, in both copies of the HSD17B4 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Deafness, Autosomal Recessive 77?

Deafness, Autosomal Recessive 77 is an autosomal recessive disorder that affects hearing.  Affected individuals usually develop hearing loss beginning in childhood.  The hearing loss worsens with age.  This condition does not cause other health problems.

What causes Deafness, Autosomal Recessive 77?

Deafness, Autosomal Recessive 77 is caused by a change, or mutation, in both copies of the LOXHD1 gene pair.  These mutations cause the genes to not work properly or not work at all.  Normal function of the LOXHD1 genes is important for hearing.  When both copies of the LOXHD1 gene do not work correctly, progressive hearing loss occurs. 

What is Duchenne/Becker Muscular Dystrophy?

Duchenne and Becker Muscular Dystrophy are inherited disorders called “Dystrophinopathies” that cause progressive breakdown and weakness of both skeletal and heart muscle. In Duchenne Muscular Dystrophy, the muscle weakness usually begins around 3 to 5 years of age and worsens over time.  By the teenage years, the muscle degeneration and weakness also starts to involve the muscles of the lungs and heart. In Becker Muscular Dystrophy, the signs and symptoms are milder and begin later in childhood. For both conditions, it is more common for boys to be affected than girls. Children and adults with Duchenne/Becker Muscular Dystrophy need physical and occupational therapy and lifelong medical treatment. Most boys with Duchenne Muscular Dystrophy will need a wheelchair by their mid to late teenage years; boys with Becker Muscular Dystrophy are often in their late teens or early adulthood before they need a wheelchair.  A variable degree of intellectual disability may occur and is more common in children with Duchenne than in children with Becker.  Presently there is no cure for Duchenne/Becker Muscular Dystrophy. With current medical treatments, survival is common into the 20s and 30s with Duchenne Muscular Dystrophy and into the 40s with Becker Muscular Dystrophy. Some males have a separate form of Dystrophinopathy called DMD-Associated Dilated Cardiomyopathy, which does not include skeletal muscle weakness. DMD-Associated Dilated Cardiomyopathy causes progressive heart problems where one or more chambers of the heart dilate, the heart muscle weakens, and congestive heart failure occurs. Symptoms typically start between the ages of 20 and 40 years and lifespan is shortened. About 1 in every 3500 males is born with Duchenne Muscular Dystrophy and about 1 in every 18,500 boys is born with Becker Muscular Dystrophy. DMD-Associated Dilated Cardiomyopathy is rare. Some female carriers develop heart problems such as dilated cardiomyopathy and some have other symptoms of Duchenne/Becker Muscular Dystrophy such as mild to moderate muscle weakness. In rare cases, female carriers may have more serious symptoms.

What causes Duchenne/Becker Muscular Dystrophy?

Duchenne/Becker Muscular Dystrophy is caused by a change, or mutation, in the DMD gene.  This mutation causes the gene to not work properly or not work at all.  When this gene does not work correctly, it leads to a lack of dystrophin, a protein normally found in muscle cells. Muscle cells in the skeleton and heart that don’t have enough dystrophin gradually stop working, leading to the symptoms described above. It is sometimes but not always possible to tell just by the mutation whether a boy will have the Duchenne or Becker form of this condition. 

What is Dyskeratosis Congenita, RTEL1-Related?

Dyskeratosis Congenita, RTEL1-Related (also called Dyskeratosis Congenita, Autosomal Recessive 5) is an autosomal recessive disorder that affects mainly the skin, bone marrow, and immune system. Signs and symptoms vary from person to person but often include immune system problems, increased pigment in the skin, abnormalities of the nails, and white patches on the insides of the mouth called oral leukoplakia. Other symptoms may include developmental delay, anemia, bone marrow failure, and heart, lung, and liver complications. People with this condition are at increased risk for developing leukemia or other cancers. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Dyskeratosis Congenita, RTEL1-Related?

Dyskeratosis Congenita, RTEL1-Related is caused by a gene change, or mutation in both copies of the RTEL1 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the RTEL1 gene do not work correctly, it leads to the symptoms described above.

What is Dystrophic Epidermolysis Bullosa, COL7A1-Related?

Dystrophic Epidermolysis Bullosa, COL7A1-Related is an inherited disorder that has two forms, autosomal recessive and autosomal dominant. The autosomal recessive form causes severe repeated blistering of the skin and mucous membranes. Blisters are usually present at birth or start forming shortly after birth. Blisters may form anywhere on the body but are found most often on the hands and feet. Blisters may also occur on internal organs, such as the esophagus, stomach, and respiratory tract. When the blisters heal, they form scars that can cause problems with hand and limb movements, eating and digesting food, and vision. Infection, malnutrition, and dehydration may cause death in some infants. Children who survive are at increased risk of developing a type of skin cancer called squamous cell carcinoma. Carriers of the autosomal recessive form of this disorder are not expected to have symptoms. The other form of Dystrophic Epidermolysis Bullosa, COL7A1-Related is inherited in an autosomal dominant manner and is typically milder. In the autosomal dominant form, nails may be absent or small. Blistering may be limited to the hands, feet, knees, and elbows, and may improve with age, although scars may be permanent. Growth is typically normal and risk of squamous cell cancer may be increased slightly or not at all.

What causes Dystrophic Epidermolysis Bullosa, COL7A1-Related?

Dystrophic Epidermolysis Bullosa, COL7A1-Related with autosomal recessive inheritance is caused by a gene change, or mutation, in both copies of the COL7A1 gene. These mutations cause the genes to not work properly or not work at all. When both copies of the COL7A1 gene pair are not working correctly, it leads to the symptoms of the autosomal recessive form described above.

Mutations in the same gene (COL7A1) sometimes cause a milder form of the condition inherited in an autosomal dominant manner. Individuals with a mutation in one COL7A1 gene are affected and have symptoms of Dystrophic Epidermolysis Bullosa, COL7A1-Related although they are usually milder than the autosomal recessive form.

What is Ehlers-Danlos Syndrome, Type VIIC?

Ehlers-Danlos Syndrome, Type VIIC is an autosomal recessive disorder of connective tissue which causes the skin to be extremely fragile and excessive bruising is common. Most people with Ehlers-Danlos Syndrome, Type VIIC have changes in their facial features that include puffy eye lids, full lips, small chin, and blue coloring of the whites of the eyes (blue sclera).  People with this condition also have short stature and small hands and feet with multiple skin folds around the fingers and ankles. Extreme flexibility of the joints (hypermobility) and skin sagging are common and worsen with age.  The skin also becomes more fragile with age and frequent skin infections may occur, which are difficult to treat. These infections can sometimes lead to early death.

What causes Ehlers-Danlos Syndrome, Type VIIC?

Ehlers-Danlos Syndrome, Type VIIC is caused by a gene change, or mutation, in both copies of the ADAMTS2 gene.  These mutations cause the genes to not work properly or not work at all.  When both copies of the ADAMTS2 gene do not work correctly, it leads to the symptoms described above.

What is Ellis-van Creveld Syndrome, EVC-Related?

Ellis-van Creveld (EVC) Syndrome, EVC-Related is an autosomal recessive disorder that causes short stature, changes in the skeleton, and other birth defects. Signs and symptoms begin before birth. Bones develop abnormally and affected infants have short forearms and lower legs, narrow chest with short ribs, and extra fingers and toes. Other symptoms that may occur include cleft lip, abnormal development of the teeth, heart defects, male genital abnormalities, underdeveloped finger- and toenails, and intellectual disability.

What causes Ellis-van Creveld Syndrome, EVC-Related?

Ellis-van Creveld Syndrome, EVC-Related is caused by a change, or mutation, in both copies of the EVC gene. These mutations cause the genes to not work properly or not work at all. Normal function of the EVC gene is important for forming the bones and other parts of the body. When both copies of the EVC gene pair do not work correctly, it results in the symptoms described above. Very rarely, a mutation in the same gene that causes Ellis-van Creveld Syndrome, EVC-Related instead causes a related autosomal dominant condition called Weyers Acrofacial Dysostosis that affects the bones, teeth, and nails. Symptoms of this condition are milder than Ellis-van Creveld Syndrome, EVC-Related and often include missing or small teeth, misshaped jaw bone, small or unusually shaped nails, and short stature. 

What is Emery-Dreifuss Muscular Dystrophy 1, X-Linked?

Emery-Dreifuss Muscular Dystrophy 1, X-Linked is an X-linked inherited disorder that affects mainly boys. It causes weakness in the muscles used for movement (skeletal muscles) and the heart muscle. Muscle weakness starts in the upper arms and lower legs and worsens to involve the muscles in the shoulders and hips. Stiff joints (contractures) occur over time and limit the movement of the elbows, ankles, and neck. Signs of Emery-Dreifuss Muscular Dystrophy 1, X-Linked usually appear by age 10. Almost all people with this disorder have heart problems by adulthood. If untreated, this can lead to an unusually slow heartbeat, fainting, and an increased risk of stroke and sudden death.  Currently there is no cure for Emery-Dreifuss Muscular Dystrophy 1, X-Linked and treatment is based on symptoms.  Some female carriers have heart problems, and, while rarer, some have other symptoms such as mild to moderate muscle weakness.

What causes Emery-Dreifuss Muscular Dystrophy 1, X-Linked?

Emery-Dreifuss Muscular Dystrophy 1, X-Linked is caused by a change, or mutation, in the EMD gene. This mutation causes the gene to not work properly or not work at all. When the EMD gene is not working correctly in a male, it leads to the symptoms described above.

What is Enhanced S-Cone Syndrome?

Enhanced S-Cone Syndrome (also known as Goldmann-Favre Syndrome) is an autosomal recessive eye disorder that causes vision loss, night blindness, cataracts, increased sensitivity to blue light, and specific findings on eye examination. Signs and symptoms usually begin in childhood and are caused by breakdown of the retina (the light sensitive tissue in the back of the eye). The symptoms progress over time and vision worsens with age. Currently there is no cure for this disorder and treatment is based on symptoms.

What causes Enhanced S-Cone Syndrome?

Enhanced S-Cone Syndrome is caused by a gene change, or mutation, in both copies of the NR2E3 gene pair. These mutations cause the genes to not work properly or not work at all. Normal function of the NR2E3 gene pair is important for the health of the retina in the eye. When both copies of the NR2E3 gene do not work correctly, it leads to the symptoms described above.

What is Ethylmalonic Encephalopathy?

Ethylmalonic Encephalopathy is an autosomal recessive disorder that reduces the body’s ability to make energy. The signs and symptoms usually start shortly after birth. Children with this disorder typically have developmental delay, seizures, weak muscle tone (hypotonia), chronic diarrhea, reduced oxygen to the hands and feet causing bluish-white coloring, and problems with the blood vessels that cause a red rash. Children with this disorder usually do not live past 10 years of age.  Special dietary treatment and supplements may help delay the progression of the symptoms.

What causes Ethylmalonic Encephalopathy?

Ethylmalonic Encephalopathy is caused by a change, or mutation, in both copies of the ETHE1 gene pair.  These mutations cause the genes to not work properly or not work at all.  The function of the ETHE1 genes is to help make energy for the cells of the body.  When both copies of this gene are not working correctly, it leads to the symptoms described above.

What is Fabry Disease?

Fabry Disease is an X-linked inherited disorder that causes a buildup of a certain type of fat in the cells of the body.  Affected males usually have signs and symptoms beginning in childhood.  Fabry Disease causes pain episodes, often of the hands and feet; red spots on the skin (angiokeratomas); lack of sweating; cloudiness of the corneas of the eyes (corneal opacity); hearing loss; slow weight gain; digestive problems and pain; progressive kidney failure; and heart disease (arrhythmia). The severity of Fabry Disease varies from person to person, with some males having mild symptoms and others having more severe disease. Over time, the symptoms of Fabry Disease can include kidney failure, stroke, and heart attacks, all of which can be life-threatening. Some females who are carriers for Fabry Disease develop some symptoms although they are usually milder.  Life-long treatment with special diet and enzyme replacement therapy is available for Fabry Disease.   

What causes Fabry Disease?

Fabry Disease is caused by a change, or mutation, in the GLA gene.  This mutation causes the gene to not work properly or not work at all.  People with Fabry do not make an enzyme that normally breaks down certain fats in the body. When these fats are not broken down and removed from the body, they build up and lead to the symptoms described above. 

What is Factor IX Deficiency?

Factor IX Deficiency, also known as Hemophilia B or Christmas disease, is an X-linked inherited bleeding disorder that affects boys more often than girls.  Factor IX is a protein that helps to clot blood after injury.  If the body does not make enough normal Factor IX, it causes longer than average bleeding times, especially following surgery, injury or trauma, and tooth extractions. The symptoms of Factor IX Deficiency can be mild, moderate, or severe and vary from person to person.  People with severe Factor IX Deficiency have symptoms that start in early childhood and have episodes of uncontrolled bleeding in the brain, joints, muscles, or other organs, even without injury.  Nosebleeds, easy bruising and blood in the urine are also common.  People with moderate Factor IX Deficiency usually show symptoms by the age of 5 or 6 and often have prolonged bleeding after minor injuries, surgeries, or tooth extraction.  Mild Factor IX Deficiency causes bleeding problems after surgery and tooth extraction but usually not with minor injury and may not be recognized until later in life.  Children with Factor IX Deficiency are likely to need lifelong medical care.  Treatment for Factor IX Deficiency often includes infusions of Factor IX to help restore normal blood clotting. 

What causes Factor IX Deficiency?

Factor IX Deficiency is caused by a change, or mutation, in the F9 gene.  This mutation causes the gene to not work properly or not work at all.  Normal function of the F9 gene is important for making Factor IX, a protein that helps in blood clotting.  When the F9 gene in a male does not work correctly, it leads to the symptoms described above. Most female carriers of Factor IX Deficiency have no symptoms; however, about 10% of female carriers have some bleeding problems, particularly after surgery, tooth extraction, or trauma.

What is Factor XI Deficiency?

Factor XI Deficiency, also called Hemophilia C, is an autosomal recessive bleeding disorder that causes mild to heavy bleeding, especially following dental tooth extraction, surgery, or trauma.  Some people with Factor XI Deficiency also experience frequent nosebleeds and bruising.  Women may have heavy menstrual cycles or postpartum bleeding.  Most people with this condition will have mild symptoms; however, symptoms may be more severe in certain cases. Treatment with medications that help blood clot more quickly may be helpful for people with severe bleeding problems.  Factor XI deficiency is considered less severe than other forms of hemophilia (types A and B). 

What causes Factor XI Deficiency?

Factor XI Deficiency is caused by a gene change, or mutation, in both copies of the F11 gene pair. These mutations cause the genes to not work properly or not work at all. Normal function of the F11 gene pair is important for making a protein that helps in blood clotting. When both copies of the F11 gene do not work correctly, it leads to the symptoms described above. Carriers have one working copy of the gene and one non-working copy. People who are carriers for Factor XI Deficiency may have some symptoms of Factor XI Deficiency such as prolonged bleeding after surgery, trauma, or tooth extraction, or they may have no symptoms at all.

What is Familial Dysautonomia?

Familial Dysautonomia is an autosomal recessive disorder that affects the nervous system. Symptoms usually start in infancy and include poor muscle tone (hypotonia), problems with feeding and digestion, episodes of vomiting, lessened sensitivity to pain, and problems keeping a normal body temperature. Children with Familial Dysautonomia may also have delays in reaching developmental milestones, such as walking.  Currently there is no cure for this disorder and treatment is based on symptoms.

What causes Familial Dysautonomia?

Familial Dysautonomia is caused by a gene change, or mutation, in both copies of the IKBKAP gene pair.  These mutations cause the genes to not work properly or not work at all.   When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Familial Hypercholesterolemia, LDLR-Related?

Familial Hypercholesterolemia, LDLR-Related is an autosomal dominant inherited disorder that causes high cholesterol levels in the body. Cholesterol is a waxy, fat-like substance that is found in all cells of the body. With Familial Hypercholesterolemia, LDLR-Related, the body is unable to remove LDL (low density lipoprotein, also known as "bad" cholesterol) from the blood. High blood levels of LDL cholesterol can lead to heart disease in adulthood and other symptoms including fatty skin deposits (xanthomas) over parts of the hands, elbows, knees, ankles, and around the cornea of the eye; cholesterol deposits in the eyelids (xanthelasmas); chest pain (angina) or other signs of coronary artery disease; sores on the toes that do not heal; and sudden stroke-like symptoms.  About 1 in 500 people has Familial Hypercholesterolemia, LDLR-Related.

When both parents have Familial Hypercholesterolemia, LDLR-Related, their children can inherit a more severe childhood-onset form of the condition called Homozygous Familial Hypercholesterolemia, LDLR-Related.  In these cases there is a much greater increase in blood cholesterol levels resulting in a high risk for heart disease and heart attacks in childhood.

What causes Familial Hypercholesterolemia, LDLR-Related?

Most cases of high cholesterol are due to a combination of genetic and lifestyle factors.  There are several inherited (familial) forms of hypercholesterolemia caused by gene changes (mutations) in different genes, most commonly the LDLR gene.  When Familial Hypercholesterolemia is caused by a mutation in the LDLR gene, it is called Familial Hypercholesterolemia, LDLR-Related.

Familial Hypercholesterolemia, LDLR-Related is caused by mutations in the LDLR gene and has an autosomal dominant pattern of inheritance. Autosomal dominant inheritance means having a change, or mutation, in one copy of a pair of genes is enough to cause the disorder.  The mutation causes the gene to not work properly or not work at all. Normal function of the LDLR gene is important in helping the body get rid of excess LDL cholesterol from the blood.   When one copy of the LDLR gene is not working properly, it causes the symptoms of Familial Hypercholesterolemia, LDLR-Related described above. 

Rarely, a child can inherit mutations in both copies of the LDLR gene pair. This happens when both parents have Familial Hypercholesterolemia, LDLR-Related (one LDLR gene mutation) and each passes their LDLR gene mutation to their child.  Children who inherit mutations in both copies of their LDLR genes have severe childhood-onset Homozygous Familial Hypercholesterolemia, LDLR-Related with symptoms that start at much younger ages than those with only one LDLR gene mutation. 

What is Familial Hypercholesterolemia, LDLRAP1-Related?

Familial Hypercholesterolemia, LDLRAP1-Related is an autosomal recessive disorder that causes very high levels of cholesterol in the blood. Cholesterol is a waxy, fat-like substance that is found in all cells of the body.  Too much cholesterol in the blood increases the risk of heart disease. With Familial Hypercholesterolemia, LDLRAP1-Related the body is unable to remove LDL (low density lipoprotein, also known as ‘bad’ cholesterol) from the blood.  High blood levels of LDL cholesterol can lead to heart disease in early adulthood.  Other symptoms include fatty skin deposits (xanthomas) over parts of the hands, elbows, knees, ankles, and around the cornea of the eye; cholesterol deposits in the eyelids (xanthelasmas); chest pain (angina) or other signs of coronary artery disease; sores on the toes that do not heal; and sudden stroke-like symptoms. Treatment usually includes a medical low-cholesterol, low-fat diet along with cholesterol lowering medication and other supplements as indicated.

What causes Familial Hypercholesterolemia- LDLRAP1-Related?

Familial Hypercholesterolemia, LDLRAP1-Related is caused by a gene change, or mutation, in both copies of the LDLRAP1 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it causes the symptoms described above.

What is Familial Hyperinsulinism, ABCC8-Related?

Familial Hyperinsulinism, ABCC8-Related is an autosomal recessive disorder that causes the insulin-making cells of the pancreas to release too much insulin. Insulin is a hormone that controls blood sugar. Too much insulin causes hypoglycemia (low blood sugar), even after eating. Symptoms of Familial Hyperinsulinism, ABCC8-Related include tiredness, irritability, and poor appetite. If untreated, repeated episodes of low blood sugar can result in breathing problems, vision problems, seizures, brain damage, intellectual disability, and coma. The symptoms of Familial Hyperinsulinism, ABCC8-Related range from mild to severe, even among affected individuals within the same family. Early diagnosis and treatment can reduce and often prevent more serious health problems. Less commonly, children with mutations in the same gene may have a different inherited disorder called Neonatal Diabetes Mellitus which is usually autosomal recessive, but is sometimes inherited in an autosomal dominant manner.

What causes Familial Hyperinsulinism, ABCC8-Related?

Familial Hyperinsulinism, ABCC8-Related is caused by a gene change, or mutation, in both copies of the ABCC8 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Familial Mediterranean Fever?

Familial Mediterranean Fever is an autosomal recessive disorder that causes episodes of inflammation and pain, often with fever and sometimes with rash or headache.  Commonly the pain involves the joints, abdomen and chest, but can happen in other parts of the body as well.  A buildup of protein in the body’s organs (amyloidosis), including the kidneys, can lead to kidney failure.  Symptoms are variable and often begin in childhood but can begin in adulthood as well, and there are rare people who never develop symptoms.  Lifelong medical treatment is often needed to help prevent attacks and organ damage.

What causes Familial Mediterranean Fever?

Familial Mediterranean Fever is caused by a gene change, or mutation, in both copies of the MEFV gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it can cause the symptoms described above.

Carriers for Familial Mediterranean Fever may have some symptoms of the disorder which are typically milder than individuals with the full condition.

What is Familial Nephrogenic Diabetes Insipidus, AQP2-Related?

Familial Nephrogenic Diabetes Insipidus, AQP2-Related is an autosomal recessive condition caused by an imbalance of water in the body. Affected individuals make too much urine, causing excessive thirst and dehydration if enough fluids are not taken in. Signs and symptoms begin in the first few months of life and include feeding problems, failure to gain weight and grow at the expected rate (failure to thrive), fever, irritability, diarrhea, and vomiting. Chronic dehydration can lead to slow growth and delayed development. Over time damage can occur to the bladder and kidneys. With treatment, affected individuals can lead healthy lives. In rare cases, symptoms do not appear until later in childhood or early adulthood. Rarely (less than 1% of the time), this condition is inherited in an autosomal dominant manner.

What causes Familial Nephrogenic Diabetes Insipidus, AQP2-Related?

Familial Nephrogenic Diabetes Insipidus, AQP2-Related is caused by a change, or mutation, in both copies of the AQP2 gene. These mutations cause the genes to not work properly or not work at all. Normal function of the AQP2 gene pair is important for how much water is put into the urine. When both copies of the AQP2 gene pair are not working, it results in the symptoms described above. 

What is Fanconi Anemia, Group A?

Fanconi Anemia, Group A is an autosomal recessive disorder that causes bone marrow failure, increased risk for cancer, and physical findings such as irregular skin coloring, malformed thumbs or forearms, short stature, kidney/urinary problems, and heart defects. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Fanconi Anemia, Group A?

Fanconi Anemia, Group A is caused by a gene change, or mutation, in both copies of the FANCA gene pair.  These mutations cause the genes to not work properly or not work at all. The job of the FANCA genes is to help repair DNA within cells. When both copies of this gene pair do not work correctly, it can cause cell death or uncontrolled cell growth which leads to the symptoms described above.

What is Fanconi Anemia, Group C?

Fanconi Anemia, Group C is an autosomal recessive disorder that causes bone marrow failure, increased risk for cancer, and physical findings such as irregular skin coloring, malformed thumbs or forearms, short stature, kidney/urinary problems, and heart defects. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

Some recent studies have suggested that carriers of Fanconi Anemia, Group C may have a slightly increased risk for certain cancers including, but not limited to, breast cancer and pancreatic cancer. However, other studies show no increased risk for cancer. The actual risk for cancer in carriers of Fanconi Anemia, Group C, if increased, is not clear and further studies need to be done.

What causes Fanconi Anemia, Group C?

Fanconi Anemia, Group C is caused by a gene change, or mutation, in both copies of the FANCC gene pair.  These mutations cause the genes to not work properly or not work at all.  The function of the FANCC genes is to help repair DNA within cells.  When both copies of this gene do not work correctly, it can cause cell death or uncontrolled cell growth which leads to the symptoms described above.

What is Fanconi Anemia, Group G?

Fanconi Anemia, Group G is an autosomal recessive disorder that causes bone marrow failure, increased risk for cancer, and physical findings such as irregular skin coloring, malformed thumbs or forearms, short stature, kidney/urinary problems, and heart defects. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Fanconi Anemia, Group G?

Fanconi Anemia, Group G is caused by a gene change, or mutation, in both copies of the FANCG gene pair.  These mutations cause the genes to not work properly or not work at all. The function of the FANCG genes is to help repair DNA within cells. When both copies of this gene pair do not work correctly, it can cause cell death or uncontrolled cell growth which leads to the symptoms described above.

What is Fragile X Syndrome?

Fragile X Syndrome is an X-linked inherited disorder.  It is the most common inherited cause of intellectual disability and occurs in about 1 in 4000 males and 1 in 8000 females. Boys with Fragile X Syndrome typically have more serious learning and behavior problems than girls. On average, boys have moderate to severe intellectual disability. Behavior and emotional problems are common, and autism spectrum disorder is sometimes present. Symptoms in girls can range from none to severe intellectual disability; however, they are most likely to be mild. At this time there is no cure for Fragile X Syndrome and treatment is based on symptoms. 

What causes Fragile X Syndrome?

Fragile X Syndrome is caused by a mutation (change) in the FMR1 gene known as a CGG repeat.  Humans typically have between 6 and 44 copies of CGG in the FMR1 gene.  In people with Fragile X Syndrome, there are more than 200 copies of CGG.  The large number of repeated CGGs causes the gene to turn off and not work properly. This leads to the specific set of learning and development problems found in Fragile X Syndrome.

A carrier for Fragile X Syndrome is someone who has a mutation (change) in one FMR1 gene. This change is called a ‘premutation’ and has between 55 and 200 CGG copies. Women who are premutation carriers have an increased chance of having children affected with Fragile X Syndrome. Occasionally, females with a premutation may have issues related to attention span such as Attention Deficit Disorder and some may have behavior problems, social anxiety, and/or difficulty with social skills. Males with a premutation tend to have a higher rate of these types of problems.

What is Fumarase Deficiency?

Fumarase Deficiency is an autosomal recessive disorder that affects the brain and nervous system.  Signs and symptoms begin in infancy and include small head size, abnormal brain development, severe developmental delay, weak muscle tone (hypotonia), and failure to gain weight and grow at the expected rate (failure to thrive). Affected infants may also have seizures, intellectual disability, unusual facial features, and enlarged liver and spleen (hepatosplenomegaly). Death often occurs in infancy but some individuals survive to early adulthood. Currently there is no cure or specific treatment for Fumarase Deficiency.

What causes Fumarase Deficiency?

Fumarase Deficiency is caused by a gene change, or mutation, in both copies of the FH gene pair. These mutations cause the genes to not work properly or not work at all. The function of the FH gene is to help the cells in the body use oxygen and make energy. When both copies of this gene pair do not work correctly, it leads to problems in brain development and causes the symptoms described above. 

Individuals who are carriers for one mutation in the FH gene have an increased risk for developing multiple skin and uterine growths called leiomyomas.   A small number of carriers of an FH mutation may have an autosomal dominant condition called Hereditary Leiomyomatosis and Renal Cell Cancer (HLRCC).  Symptoms of HLRCC usually begin in early adulthood and include benign growths (leiomyomas) in the skin and uterus, and an increased risk for a specific type of kidney cancer called papillary renal cell cancer. 

What is Galactokinase Deficiency (Galactosemia, Type II)?

Galactokinase Deficiency, also known as Galactosemia, Type II, is an autosomal recessive condition in which the body cannot digest a type of sugar called galactose.  Galactose is found in milk and dairy products as well as some fruits and vegetables.  If children with Galactokinase Deficiency eat food containing galactose, it builds up in the blood and will cause cataracts (clouding of the lens of the eye). When the condition is found and treated early, cataracts usually don’t develop.  Treatment usually includes a medical diet low in galactose along with specific supplements. 

What causes Galactokinase Deficiency (Galactosemia, Type II)?

Galactokinase Deficiency is caused by a gene change, or mutation, in both copies of a gene called GALK1. These mutations cause the genes to not work properly or not work at all.  The GALK1 gene pair is needed to help the body break down the sugar called galactose.  When both copies of the GALK1 gene do not work correctly, galactose builds up in the body and can cause cataracts. 

What is Galactosemia?

Galactosemia is an autosomal recessive disorder that affects how the body breaks down a sugar called galactose.  Galactose is present in many foods including dairy products.  For individuals with Galactosemia, the body cannot use galactose to make energy.  Unless treatment is started early in life, a toxic buildup of certain sugars happens in the body leading to health problems.

Affected children may have classic or variant Galactosemia.  Treatment of classic Galactosemia usually involves a galactose and lactose free diet. Without treatment, classic Galactosemia is associated with life-threatening complications that can appear within days after birth.  Affected infants typically develop feeding problems, a lack of energy (lethargy), failure to gain weight and grow as expected (failure to thrive), yellowing of the skin and whites of the eyes (jaundice), liver damage, and bleeding.  Affected children may also have delayed development, clouding of the lens of the eye (cataract), speech difficulties, and intellectual disability.  Children with variant Galactosemia can have milder symptoms and may require less treatment than children with classic Galactosemia.  With treatment many children with Galactosemia can lead healthy lives. 

What causes Galactosemia?

Galactosemia is caused by a gene change, or mutation, in both copies of the GALT gene pair.  These mutations cause the genes to not work properly or not work at all. The function of the GALT genes is to break down the sugar galactose in the body that comes from food.  When both copies of this gene do not work correctly it leads to the symptoms described above.

What is Gaucher Disease?

Gaucher Disease is an autosomal recessive disorder that commonly affects the liver, spleen, and bone marrow. Gaucher Disease, Type 1 is the most common form of the disease and causes enlarged liver and spleen with bone abnormalities.  Gaucher Types 2 and 3 cause brain and nervous system problems such as seizures and low muscle tone (hypotonia) in addition to the other symptoms listed above. Lifelong enzyme replacement therapy can help prevent or lessen some of the symptoms. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

Recent studies suggest that carriers for Gaucher Disease may have a slightly increased risk of developing Parkinson’s disease in late adulthood; however, most carriers never develop this condition.

What causes Gaucher Disease?

Gaucher Disease is caused by a gene change, or mutation, in both copies of the GBA gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Gitelman Syndrome?

Gitelman Syndrome is an autosomal recessive disorder that causes kidney problems.  In people with Gitelman Syndrome, the kidneys cannot filter certain substances correctly from the blood to urine.  This leads to an imbalance of potassium, magnesium, and calcium in the blood. The signs and symptoms of Gitelman Syndrome vary from person to person and are often mild.  Symptoms usually appear in late childhood or the teenage years and may include painful muscle spasms, muscle weakness or cramping, dizziness, and salt craving.  Also common is a tingling or prickly sensation in the skin, most often on the face.  Some people also have chronic tiredness, low blood pressure, an abnormal heart rhythm, and a painful joint condition called chondrocalcinosis.  Treatment with magnesium salt supplements is effective in preventing or lessening the symptoms, although most people with Gitelman Syndrome never need treatment.

Carriers of Gitelman Syndrome may have lower than average blood pressure but do not typically have other symptoms.

What causes Gitelman Syndrome?

Gitelman Syndrome is most often caused by a gene change, or mutation, in both copies of the SLC12A3 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Glutaric Acidemia, Type 1?

Glutaric Acidemia, Type 1 (also called Glutaryl-CoA Dehydrogenase Deficiency) is an autosomal recessive disorder that causes the body to be unable to break down certain proteins from food for use in the body. Signs and symptoms of Glutaryl-CoA Dehydrogenase Deficiency, Type 1 usually begin between age 4 months and 2 years and include fatigue, irritability, weak muscle tone, growth delay poor appetite, vomiting, fever, tight muscles, and excessive sweating. Some affected children have intellectual disability. The problems associated with Glutaryl-CoA Dehydrogenase Deficiency. Type 1 may worsen after going a long time without food or with illness. With early diagnosis and treatment, affected children can have healthy growth and development.

What causes Glutaric Acidemia, Type 1?

Glutaric Acidemia, Type 1 is caused by a gene change, or mutation, in both copies of the GCDH gene. These mutations cause the genes to not work properly or not work at all. When both copies of this gene pair do not work correctly, it leads to the symptoms describe above. 

What is Glutaric Acidemia, Type 2A?

Glutaric Acidemia, Type 2A is an autosomal recessive disorder that causes the body to be unable to break down certain fats and proteins from food to make energy. Signs and symptoms of Glutaric Acidemia, Type 2A usually begin in infancy and include fatigue, irritability, weak muscle tone, a “sweaty feet” smell, feeding problems, vomiting, diarrhea, and low blood sugar. Infants born with this condition may have kidney defects, enlarged liver, abnormal brain development, and genital abnormalities. The problems associated with Glutaric Acidemia, Type 2A may worsen with going a long time without food or with illness and can be life-threatening. In some cases symptoms are milder and begin later in childhood or adulthood. With early diagnosis and treatment, some of the more severe problems in Glutaric Acidemia, Type 2A may be avoided.

What causes Glutaric Acidemia, Type 2A?

Glutaric Acidemia, Type 2A is caused by a gene change, or mutation, in both copies of the ETFA gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene pair do not work correctly, it leads to the symptoms describe above. 

What is Glutaric Acidemia, Type 2C?

Glutaric Acidemia, Type 2C is an autosomal recessive disorder that causes the body to be unable to break down certain fats and proteins from food to make energy. Signs and symptoms of Glutaric Acidemia, Type 2C usually begin in infancy and include fatigue, irritability, weak muscle tone, a “sweaty feet” smell, feeding problems, vomiting, diarrhea, and low blood sugar. Infants born with this condition may have kidney defects, enlarged liver, abnormal brain development, and genital abnormalities. The problems associated with Glutaric Acidemia, Type 2C may worsen with going a long time without food or with illness and can be life-threatening. In some cases symptoms are milder and begin later in childhood or adulthood. With early diagnosis and treatment, some of the more severe problems in Glutaric Acidemia, Type 2C may be avoided.

What causes Glutaric Acidemia, Type 2C?

Glutaric Acidemia, Type 2C is caused by a gene change, or mutation, in both copies of the ETFDH gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene pair do not work correctly, it leads to the symptoms describe above. 

What is Glycine Encephalopathy, AMT-Related?

Glycine Encephalopathy, AMT-Related, also known as nonketotic hyperglycinemia (NKH), is an autosomal recessive disorder that mainly affects the brain and nervous system.  It causes a toxic buildup in the body of a building block of protein called glycine.  Affected individuals usually have symptoms shortly after birth including extreme tiredness, feeding problems, weak muscle tone, jerking movements, and breathing problems that worsen and become life-threatening.  Many affected children die in infancy.  Children who survive with Glycine Encephalopathy, AMT-Related have intellectual disability, seizures, and abnormal movements.  Affected males may have greater chance of survival than affected females.  Some affected individuals have a milder disease with symptoms that begin in childhood or adulthood. 

What causes Glycine Encephalopathy, AMT-Related?

Glycine Encephalopathy, AMT-Related is caused by a gene change, or mutation, in both copies of the AMT gene pair. These mutations cause the genes to not work properly or not work at all. The function of the AMT gene pair is to break down glycine (a building block of protein) in the body. When both copies of this gene do not work correctly, it leads to a buildup of glycine in the body, especially the brain, which causes the symptoms described above. 

What is Glycine Encephalopathy, GLDC-Related?

Glycine Encephalopathy, GLDC-Related, also known as nonketotic hyperglycinemia (NKH), is an autosomal recessive disorder that causes damage to the brain and nervous system.  Lack of a certain enzyme in the body leads to a toxic buildup in the body of a building block of protein called glycine.  Affected individuals usually have symptoms shortly after birth including extreme tiredness, feeding problems, weak muscle tone, jerking movements, and breathing problems that worsen and become life-threatening.  Many affected children die in infancy.  Children who survive with Glycine Encephalopathy, GLDC-Related have intellectual disability, seizures, and abnormal movements.  Affected males may have greater chance of survival than affected females.  Some affected individuals have a milder disease with symptoms that begin in childhood or adulthood. 

What causes Glycine Encephalopathy, GLDC-Related?

Glycine Encephalopathy, GLDC-Related is caused by a gene change, or mutation, in both copies of the GLDC gene pair.  These mutations cause the genes to not work properly or not work at all. The function of the GLDC genes is to breakdown glycine (a building block of protein) in the body. When both copies of this gene pair do not work correctly, it leads to a buildup of glycine in the body, especially the brain, which causes the symptoms described above. 

What is Glycogen Storage Disease, Type 1a?

Glycogen Storage Disease, Type 1a (GSD1a), is an autosomal recessive disorder with signs and symptoms that begin in infancy.  Fat and glycogen (stored sugar) build up in the liver and kidneys and cause enlarged liver and kidney problems.  Other symptoms include growth problems, loaw blood sugar (hypoglycemia), and sometimes seizures.  Currently there is no cure for this condition.  However, if started early, medical treatment, including a special medical diet and medications, can help prevent or lessen some of the symptoms. 

What causes Glycogen Storage Disease, Type 1a?

Glycogen Storage Disease, Type 1a is caused by a gene change, or mutation, in both copies of the G6PC gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms listed above.

What is Glycogen Storage Disease, Type 1b?

Glycogen Storage Disease, Type 1b (GSD1b) is an autosomal recessive disorder that causes a stored form of sugar called glycogen to build up in the cells of the body. Glycogen builds up in the liver, kidneys, and small intestines, causing these organs not to function correctly. Symptoms begin in the first few months of life and include low blood sugar, enlarged liver, short stature, delayed puberty, and high amounts of uric acid and cholesterol in the blood.  Some children with GSD1b have repeated bacterial infections caused by low levels of a type of white blood cell called neutrophils (neutropenia). Some affected people may also develop chronic inflammation of the pancreas, gum disease, chronic inflammatory bowel disease, and or Crohn's disease. Medical and dietary treatment helps lessen the effects of GSD1b.

What causes Glycogen Storage Disease, Type 1b?

Glycogen Storage Disease, Type 1b is caused by a gene change, or mutation, in both copies of the SLC37A4 gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Glycogen Storage Disease, Type 2 (Pompe Disease)?

Glycogen Storage Disease, Type 2, also known as Pompe Disease or GSD2, is an autosomal recessive disorder that causes progressive weakness in the muscles used for movement and breathing. People with Glycogen Storage Disease, Type 2 are missing an enzyme that breaks down glycogen, a stored form of sugar used for energy by the muscles. As a result, glycogen builds up in the body, mostly in the muscles, and damages these cells. There are two main forms of Glycogen Storage Disease, Type 2, infantile-onset and late-onset. The infantile form is the most common and most severe type of Glycogen Storage Disease, Type 2. Infants may appear normal at birth but begin to show symptoms in the first few months of life. Symptoms include decreased muscle tone (hypotonia), muscle weakness, difficulty feeding, delayed growth, breathing problems, enlarged liver and heart, and sometimes an enlarged tongue.  The infantile form of Glycogen Storage Disease, Type 2 progresses quickly and most untreated infants will die within the first year of life.  Enzyme replacement therapy may slow down the progression of heart disease and muscle weakness. Symptoms of late-onset Glycogen Storage Disease, Type 2 can begin at any time from childhood to adulthood.  Symptoms include progressive muscle weakness and problems with breathing, often leading to the need for wheelchair and breathing machine assistance. This form of the disease progresses more slowly, especially with enzyme-replacement therapy.

What causes Glycogen Storage Disease, Type 2 (Pompe Disease)?

Glycogen Storage Disease, Type 2 is caused by a gene change, or mutation, in both copies of the GAA gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of the gene do not work correctly, it leads to the symptoms described above.

What is Glycogen Storage Disease, Type 3?

Glycogen Storage Disease, Type 3, also called GSD3, is an autosomal recessive disorder in which the body is unable to break down the stored form of sugar called glycogen. This causes glycogen to build up in body cells and results in damage to certain organs and tissues, especially the liver and muscles.

Infants with Glycogen Storage Disease, Type 3 may have low blood sugar (hypoglycemia), high cholesterol, and high liver enzymes. Children with Glycogen Storage Disease, Type 3 commonly develop an enlarged liver, leading to a noticeably swollen abdomen. Liver size usually returns to normal later in childhood, but long term liver damage may occur. A slower than average growth rate, muscle weakness, and an enlarged heart are also common in children with Glycogen Storage Disease, Type 3.  In rare cases symptoms may be milder and may not occur until adulthood.  Medical and dietary treatments often lessen the effects of Glycogen Storage Disease, Type 3.

What causes Glycogen Storage Disease, Type 3?

Glycogen Storage Disease, Type 3 is caused by a gene change, or mutation, in both copies of the AGL gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Glycogen Storage Disease, Type 4?

Glycogen Storage Disease, Type 4, also called Andersen disease or GSD4, is an autosomal recessive disorder caused by the lack of a particular enzyme called glycogen branching enzyme. The absence of this enzyme causes glycogen – a form of stored sugar that is broken down by the body and used for energy in the cells – to build up in the body.  This buildup leads to scarring (cirrhosis) and damage of the tissues and organs where glycogen is stored, especially the liver and muscles. There are many forms of Glycogen Storage Disease, Type 4 and the symptoms range from mild to severe. Glycogen Storage Disease, Type 4 often causes symptoms in infancy with poor feeding and growth (failure to thrive), an enlarged liver and spleen, enlarged heart, low muscle tone (hypotonia), and muscle wasting. Liver cirrhosis appears very early, worsens with age, and can lead to death before age five. Childhood symptoms of Glycogen Storage Disease, Type 4 may include muscle weakness and heart disease that worsen as the child gets older.  Lifespan is typically shortened in the more severe forms of Glycogen Storage Disease, Type 4. Rarely, specific mutations in the same gene cause a different disorder called Adult Polyglucosan Body Disease.  Symptoms of this condition typically start in mid-adulthood and include peripheral neuropathy (loss of sensation in the arms and legs due to progressive breakdown of the nerves), impairment of the nerves of the bladder, muscle weakness and stiffness.  Some people with this condition also develop dementia.  It is sometime, but not always, possible to tell whether a specific gene mutation will cause Glycogen Storage Disease, Type 4 or Adult Polyglucosan Body Disease.

What causes Glycogen Storage Disease, Type 4?

Glycogen Storage Disease, Type 4 is caused by a change, or mutation, in both copies of the GBE1 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the GBE1 gene do not work correctly, it leads to the symptoms described above.

What is Glycogen Storage Disease, Type 5 (McArdle Disease)?

Glycogen Storage Disease, Type 5, also called McArdle disease or GSD5, is an autosomal recessive disorder in which the body cannot change glycogen to glucose, the sugar used by the body for energy. This leads lack of enough energy for muscle cells to work properly. The symptoms of Glycogen Storage Disease, Type 5 can vary from mild to severe and commonly occur in young adults between the ages of 20 and 30.  Symptoms include muscle cramping, pain, weakness, soreness, and fatigue when exercising. Individuals with this disorder may also experience blood in the urine and temporary kidney failure.

What causes Glycogen Storage Disease Type 5 (McArdle Disease)?

Glycogen Storage Disease, Type 5 is caused by a change, or mutation, in both copies of the PYGM gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Glycogen Storage Disease, Type 7?

Glycogen Storage Disease Type 7, also referred to as Tarui Disease or GSD7, is an autosomal recessive disorder caused by the lack of an enzyme which is needed to breakdown glycogen, a stored form of sugar used for energy in muscle cells during exercise. GSD7 usually begins in childhood with symptoms of muscle weakness, pain and stiffness during exercise, nausea and vomiting, and dark red-colored urine. Breakdown of muscle tissue can also occur. A rare form of GSD7 occurs in infants that causes progressive loss of muscle tone (hypotonia), muscle weakness, and death. A late-onset form occurs in adults who experience only muscle weakness.

What causes Glycogen Storage Disease, Type 7?

GSD7 is caused by a gene change, or mutation, in both copies of the PFKM gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is GRACILE Syndrome?

GRACILE Syndrome is an autosomal recessive disorder in which the parts of the cells in the body that make energy (the mitochondria) do not work properly. GRACILE Syndrome stands for Growth Retardation, Aminoaciduria, Cholestasis, Iron overload, Lactic acidosis, and Early death. Signs and symptoms begin during pregnancy and continue in infancy and include failure to grow and gain weight at the normal rate. Iron builds up in the liver leading to liver damage. Affected infants also have a buildup of a toxic substance called lactic acid in the blood. Kidney problems also develop. Due to the severe health problems caused by GRACILE Syndrome, affected infants usually die within the first days or months of life.

Sometimes, changes, or mutations, in the same gene cause one of a number of different inherited disorders – either Mitochondrial Respiratory Chain Complex III Deficiency, Leigh Syndrome, or Bjornstad Syndrome. Currently there is no cure for any of these conditions and treatment is based on symptoms.

What causes GRACILE Syndrome?

GRACILE Syndrome is caused by mutations in both copies of the BCS1L gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the BCS1L gene do not work correctly, the mitochondria do not work properly, leading to the symptoms described above.

What is Guanidinoacetate Methyltransferase Deficiency?

Guanidinoacetate Methyltransferase Deficiency is an autosomal recessive disorder that affects the brain and muscles. Symptoms of this disorder are usually first observed in infancy or childhood and include epileptic seizures, intellectual disability, difficulty with speech, and autistic-like behaviors. Other symptoms may also occur including muscle weakness, delayed motor skills, and involuntary movements such as tremors. Children with this condition who receive early treatment may have less severe symptoms and, in some cases, may show normal development.

What causes Guanidinoacetate Methyltransferase Deficiency?

Guanidinoacetate Methyltransferase Deficiency is caused by a change, or mutation, in both copies of the GAMT gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Hemochromatosis Type 2A?

Hemochromatosis Type 2A, also called Juvenile Hemochromatosis, is an autosomal recessive iron overload disorder in which the body absorbs too much iron from food. This extra iron is stored in the organs and causes damage, especially in the liver, skin, pancreas, heart, joints, and testes. If the condition is not treated, signs and symptoms of Hemochromatosis Type 2A begin in early childhood. Too much iron in the body causes joint pain (arthritis), liver disease, diabetes, skin discoloration, excessive tiredness, and heart disease that usually becomes severe by age 30. Decreased function of the ovaries and testes, known as hypogonadism, is also common. This leads to a loss of menstrual cycles for women and a delay in puberty or lowered sex drive for men.  If the condition is not treated, lifespan is shortened.  Treatment with periodic blood withdrawal, which removes the excess iron, is helpful in preventing or slowing the onset and severity of symptoms but cannot reverse damage that has already occurred.

What causes Hemochromatosis Type 2A?

Hemochromatosis Type 2A is caused by a gene change, or mutation, in both copies of the HFE2 gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of this gene pair are not working correctly it leads to the symptoms described above.

What is Hemochromatosis, Type 3, TFR2-Related?

Hemochromatosis, Type 3, TFR2-Related is an autosomal recessive iron overload disorder in which the body absorbs too much iron from food. This extra iron is stored in the organs and causes damage, especially in the liver, skin, pancreas, heart, joints, and testes. If the condition is not treated, signs and symptoms of Hemochromatosis, Type 3, TFR2-Related usually begin before age 30. Too much iron in the body causes liver disease, diabetes, skin discoloration, excessive tiredness, joint pain (arthritis), and heart disease. Decreased function of the ovaries and testes, known as hypogonadism, is also common. This leads to a decrease in menstrual cycles for women and lowered sex drive for men. Treatment with periodic blood withdrawal, which removes the excess iron, is very effective at preventing new symptoms but cannot reverse damage that has already occurred.

What causes Hemochromatosis, Type 3, TFR2-Related?

Hemochromatosis, Type 3, TFR2-Related is caused by a gene change, or mutation, in both copies of the TFR2 gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of this gene pair do not work correctly, it leads to the symptoms described above.

What is Hepatocerebral Mitochondrial DNA Depletion Syndrome, MPV17-Related?

Hepatocerebral Mitochondrial DNA Depletion Syndrome, MPV17-Related (also called Mitochondrial DNA Depletion Syndrome 6) is an autosomal recessive disorder that causes liver disease and neurological problems. Symptoms usually start shortly after birth and include vomiting, lack of energy, low blood sugar (hypoglycemia), diarrhea, and poor growth. Enlargement of the liver and liver disease also occur and worsen quickly, often leading to liver failure. Neurologic problems include muscle weakness, developmental delay, and a loss of sensation in the arms and legs. There is no treatment for this condition and infants with Hepatocerebral Mitochondrial DNA Depletion Syndrome, MPV17-Related usually do not live past early childhood.

What causes Hepatocerebral Mitochondrial DNA Depletion Syndrome, MPV17-Related?

Hepatocerebral Mitochondrial DNA Depletion Syndrome, MPV17-Related is caused by a change, or mutation, in both copies of the MPV17 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Hereditary Fructose Intolerance?

Hereditary Fructose Intolerance is an autosomal recessive disorder in which the body is unable to use fructose, a sugar found in many fruits as well as table sugar (sucrose).  People who have Hereditary Fructose Intolerance become sick when they eat foods containing fructose or sucrose.  Symptoms can be mild or severe.  If untreated, the condition can lead to some or all of the following after eating foods with fructose or sucrose:  hypoglycemia (low blood sugar), sweating, confusion, seizures, kidney damage, liver failure, and coma.   Hereditary Fructose Intolerance can be life-threatening in infants and ranges from mild to severe in older children and adults.  Early diagnosis and diet changes begun in infancy can reduce and often prevent these more serious problems.

What causes Hereditary Fructose Intolerance?

Hereditary Fructose Intolerance is caused by a gene change, or mutation, in both copies of the ALDOB gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, fructose builds up in the body and, if untreated, results in the symptoms described above. 

What is Hereditary Spastic Paraparesis, Type 49?

Hereditary Spastic Paraparesis, Type 49 (also known as Spastic Paraplegia 49, Autosomal Recessive) is one of a group of hereditary disorders that affect the muscles of the hips and legs. Symptoms of Hereditary Spastic Paraparesis, Type 49 usually start in infancy. Symptoms vary from person to person but typically include delayed walking, balance problems, muscle stiffness (spasticity) and weakness in the legs, developmental delay with intellectual disability, distinct facial features, and short stature. The muscle weakness and spasticity worsens over time. Currently there is no cure or specific treatment for this condition.

What causes Hereditary Spastic Paraparesis, Type 49?

Hereditary Spastic Paraparesis, Type 49 is caused by a gene change, or mutation, in both copies of the TECPR2 gene pair.  These mutations cause the genes to not work properly or not work at all.  If both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Hermansky-Pudlak Syndrome, HPS1-Related?

Hermansky-Pudlak Syndrome, HPS1-Related is an autosomal recessive disorder that causes albinism (decreased color, or pigment, in the skin, hair, and eyes), bleeding problems, and may cause pulmonary fibrosis (scarring in the lungs).  The lack of pigment (albinism) causes abnormal eye movements (nystagmus), vision problems, and an increased risk for skin cancer. People with this condition also have problems with blood clotting, leading to bruising and easy bleeding.  Pulmonary fibrosis occurs in some people and typically begins in around the age of 30; the lung scarring leads to breathing problems that often result in death within about ten years after symptoms begin. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Hermansky-Pudlak Syndrome, HPS1-Related?

Hermansky-Pudlak Syndrome, HPS1-Related is caused by a gene change, or mutation, in both copies of the HPS1 gene pair.  The function of the HPS1 gene pair is to help make pigment in the skin, hair and eyes, as well as to help with blood clotting.  When both copies of the HPS1 gene are not working correctly, it causes the symptoms described above. 

What is Hermansky-Pudlak Syndrome, HPS3-Related?

Hermansky-Pudlak Syndrome, HPS3-Related is an autosomal recessive disorder that causes albinism, eye problems, and bleeding problems. Albinism leads to decreased pigment, or color, in the skin, hair, and eye. Due to the reduced pigment, people with this disorder are at increased risk for skin cancer, abnormal eye movements (nystagmus), and vision loss.  Blood clotting problems may also occur. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Hermansky-Pudlak Syndrome, HPS3-Related?

Hermansky-Pudlak Syndrome, HPS3-Related is caused by a gene change, or mutation, in both copies of the HPS3 gene pair.  These mutations cause the genes to not work properly or not work at all. The function of the HPS3 gene pair is to help make pigment in the skin, hair and eyes, as well as to help with blood clotting.  When both copies of the HPS3 gene are not working correctly, it causes the symptoms described above.

What is Holocarboxylase Synthetase Deficiency?

Holocarboxylase Synthetase Deficiency, also called Multiple Carboxylase Deficiency, is an autosomal recessive disorder in which the body cannot properly use a B vitamin called biotin.  The disorder is easily and effectively treated with large doses of oral biotin prescribed by a doctor.  If treatment is not started early, signs and symptoms typically appear in the first few months of life but may also begin later in childhood. If untreated, Holocarboxylase Synthetase Deficiency can cause delayed development, seizures, weak muscle tone (hypotonia), breathing problems, hearing and vision loss, movement and balance problems, skin rashes, hair loss, and yeast infections.  Lifelong treatment with biotin supplementation can prevent the symptoms from occurring. With early diagnosis and treatment with biotin, people with Holocarboxylase Synthetase Deficiency can live healthy lives.

What causes Holocarboxylase Synthetase Deficiency?

Holocarboxylase Synthetase Deficiency is caused by a gene change, or mutation, in both copies of the HLCS gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Homocystinuria due to Deficiency of MTHFR?

Homocystinuria due to Deficiency of MTHFR is an autosomal recessive disorder that causes an abnormal buildup of the amino acid homocysteine and a decreased amount of the amino acid methionine in the blood. Signs and symptoms of Homocystinuria due to Deficiency of MTHFR often begin in infancy but can start as late as adolescence.  Symptoms can include breathing problems, developmental delays, intellectual disabilities, movement problems, seizures, abnormal blood clotting and strokes, a small head size, and psychiatric disorders. Medical treatment to attempt to reduce symptoms includes amino acid supplements (including high dose betaine), vitamin B12, folic acid, and other supplements.

What causes Homocystinuria due to Deficiency of MTHFR?

Homocystinuria due to Deficiency of MTHFR is caused by a gene change, or mutation, in both copies of the MTHFR gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the MTHFR gene pair do not work correctly, homocysteine builds up in the blood and the amount of folate decreases, which leads to the symptoms described above.

What is Homocystinuria, CBS-Related?

Homocystinuria, CBS-Related is an autosomal recessive disorder that causes an abnormal buildup of the amino acid homocysteine and other toxic substances in the blood. The severity and number of symptoms varies from person to person. Some or all of the following symptoms can occur: developmental delays and intellectual disabilities, nearsightedness (myopia), dislocation of the lens in the front of the eye, abnormal blood clotting, and brittle bones (osteoporosis). People with this condition are often tall and slender. There are two forms of Homocystinuria, CBS-Related. One form is Vitamin B6-responsive, which is usually milder, and the other is B6-nonresponsive. Treatment includes a low protein diet and vitamin supplementation, including vitamin B6 for people who have the B6-responsive type.

What causes Homocystinuria, CBS-Related?

Homocystinuria, CBS-Related is caused by a change, or mutation, in both copies of the CBS gene pair. These mutations cause the genes to not work properly or not work at all. The function of the CBS genes is to process the amino acid homocysteine into cystathionine. When both copies of this gene pair do not work correctly, homocysteine and other substances build up in the blood which leads to the symptoms described above.

Carriers of Homocystinuria, CBS-Related do not have the disorder but they are more likely to be deficient in vitamin B12 and folic acid.

What is Homocystinuria, Type cblE?

Homocystinuria, Type cblE is an autosomal recessive disorder in which the body cannot use the vitamin B12 (cobalamin) correctly.  This leads to an abnormal buildup of the amino acid homocysteine and other toxic substances in the blood.  Symptoms of Homocystinuria, Type cblE vary from person to person but usually begin within the first two years of life and can include small head and brain (microcephaly), lack of energy, feeding problems, developmental delay, intellectual disability, seizures, vision problems, poor muscle tone (hypotonia), and large red blood cells (megaloblastic anemia).  Some people with this condition have milder symptoms that start in the teen years or early adulthood and may include behavior and personality changes, hallucinations, mental illness, and decline in memory and skills. Treatment, which includes daily supplements and medication, helps to reduce the symptoms but cannot reverse any damage that has already occurred.

What causes Homocystinuria, Type cblE?

Homocystinuria, Type cblE is caused by a gene change, or mutation, in both copies of the MTRR gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, homocysteine builds up in the blood which leads to the symptoms described above.

Carriers of Homocystinuria, Type cblE do not have the disorder but they are more likely to be deficient in vitamin B12 and folic acid.

What is Hydrolethalus Syndrome?

Hydrolethalus Syndrome is an autosomal recessive disorder in which infants are born with extra fingers and toes, brain malformations, hydrocephalus (water on the brain), and heart defects.  During pregnancy there is often too much amniotic fluid, and preterm delivery is common.  Infants with Hydrolethalus Syndrome are usually stillborn or die during infancy.  There is no cure or treatment for this disorder.   

What causes Hydrolethalus Syndrome?

Hydrolethalus Syndrome is caused by a gene change, or mutation, in both copies of the HYLS1 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Hyperornithinemia-Hyperammonemia-Homocitrullinuria (HHH Syndrome)?

Hyperornithinemia-Hyperammonemia-Homocitrullinuria (HHH Syndrome), also called Ornithine Translocase Deficiency, is an autosomal recessive disorder that causes ammonia to build up in the blood. Ammonia is formed when proteins are broken down in the body and is toxic if the levels become too high. The age of onset and severity of symptoms vary from person to person.  Infants with the severe form of HHH Syndrome have episodes of low energy (lethargy), feeding problems, vomiting, seizures, and sometimes coma.  They often have problems controlling their breathing and body temperature and may have unusual body movements. Other symptoms of HHH Syndrome can include developmental delay, learning disabilities, muscle tension and stiffness (spasticity), and liver problems. Later-onset (childhood or adult) forms of HHH Syndrome are usually less severe and may include episodes of high blood ammonia after high-protein meals, during illness, or after long periods without food (fasting).  These episodes can include vomiting, lethargy, coordination and movement problems, confusion, headaches, and blurred vision. Treatment includes a medical low-protein diet along with special supplements and medications to lower the amount of ammonia in the blood.

What causes Hyperornithinemia-Hyperammonemia-Homocitrullinuria (HHH Syndrome)?

Hyperornithinemia-Hyperammonemia-Homocitrullinuria (HHH Syndrome) is caused by a change, or mutation, in both copies of the SLC25A15 gene pair.  These mutations cause the genes to not work properly or not work at all.  The SLC25A15 genes make an enzyme that helps the body break down nitrogen from food.  When both copies of the SLC25A15 gene do not work correctly, nitrogen builds up in the blood as ammonia, causing the symptoms described above. 

What is Hypohidrotic Ectodermal Dysplasia, X-Linked?

Hypohidrotic Ectodermal Dysplasia, X-Linked is an X-linked inherited disorder that causes sparse body hair, reduced ability to sweat, and the absence of teeth. People with Hypohidrotic Ectodermal Dysplasia, X-Linked need to keep cool during hot weather, may need special hair care products or wigs, and need to visit the dentist early in childhood.  Dentures or other dental restoration may be offered in childhood. Growth and development are otherwise normal. Girls tend to have fewer and milder symptoms of Hypohidrotic Ectodermal Dysplasia, X-Linked while boys show more features of the condition. 

What causes Hypohidrotic Ectodermal Dysplasia, X-Linked?

Hypohidrotic Ectodermal Dysplasia, X-Linked is caused by a change, or mutation, in the EDA gene.  This mutation causes the gene to not work properly or not work at all.  People with Hypohidrotic Ectodermal Dysplasia, X-Linked either have an absence of or a non-working form of a protein called ectodysplasin-A in their cells. When this protein is missing or does not work correctly it leads to the symptoms described above.

What is Hypophosphatasia, ALPL-Related?

Hypophosphatasia, ALPL-Related is a disorder inherited in either an autosomal recessive or autosomal dominant pattern that causes weakened bones and teeth. Symptoms vary from person to person and may start in infancy or not until later in childhood or adulthood. Infants with the severe form of this disorder have short bowed limbs, an abnormally shaped chest, and soft skull bones. Other symptoms may include feeding difficulties, growth delays, breathing problems, too much calcium in the blood, vomiting, and kidney disease, which can sometimes be life-threatening. In some cases symptoms do not start until later childhood or early adulthood, are often less severe, and can include early loss of baby teeth and then adult teeth, bowed legs, repeated bone fractures, softening of the bones (osteomalacia), short stature, and enlarged painful joints. Some people with a milder form of this condition typically only have abnormalities of the teeth, excess cavities, and early loss of teeth with no other symptoms.

What causes Hypophosphatasia, ALPL-Related?

Hypophosphatasia, ALPL-Related is caused by a gene change, or mutation, in one or both copies of the ALPL gene pair. The mutation or mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the mild or severe symptoms described above. People who have a mutation in one copy of the ALPL gene but not the other may have mild symptoms of Hypophosphatasia or may have no symptoms at all. 

What is Inclusion Body Myopathy 2?

Inclusion Body Myopathy 2 is an autosomal recessive disorder that causes progressive muscle weakness in the legs and arms. Signs and symptoms of this disorder usually start in the late teenage years or early twenties but some people do not have problems until their thirties or forties.  The first symptom is typically weakness in the muscles of the lower leg.  As these muscles slowly weaken, walking becomes more difficult. The ability to walk is usually lost about 20 years after symptoms first appear.  Muscle weakness worsens and starts to affect the muscles of the hips, hands, shoulders, neck, and occasionally the face.  Intelligence is not affected.  A small number of people with the gene mutations that cause this condition never show symptoms.  Currently there is no cure for Inclusion Body Myopathy 2 and treatment is based on symptoms. Very rarely, a mutation in the same gene will cause a separate disorder called Sialuria, which is inherited in a different manner. Symptoms of Sialuria are variable but include jaundice at birth, enlarged liver and spleen, and a type of anemia that causes very small red blood cells (microcytic anemia). Children with this condition have repeated respiratory infections and digestive problems. Some affected children also have seizures, learning disabilities, and episodes of dehydration. Some people with Sialuria have very mild symptoms that tend to improve as they get older.  

What causes Inclusion Body Myopathy 2?

Inclusion Body Myopathy 2 is caused by a gene change, or mutation, in both copies of the GNE gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it results in the symptoms described above.

Sialuria, a very rare disorder, is inherited in an autosomal dominant manner. Individuals with a Sialuria-causing mutation in just one copy of the GNE gene will be affected with Sialuria.  

What is Infantile Cerebral and Cerebellar Atrophy?

Infantile Cerebral and Cerebellar Atrophy is an autosomal recessive disorder that affects the brain.  Signs and symptoms begin in infancy and include small head size, abnormal brain development, seizures, feeding problems, and failure to grow at the normal rate.  Affected children do not achieve developmental milestones and have severe intellectual disability.  Currently there is no cure for this disorder and treatment is based on symptoms.

What causes Infantile Cerebral and Cerebellar Atrophy?

Infantile Cerebral and Cerebellar Atrophy is caused by a gene change, or mutation, in both copies of the MED17 gene pair.  These mutations cause the genes to not work properly or not work at all. The MED17 genes are important for brain development.  When both copies of this gene do not work correctly, it leads abnormal development of the brain and to the symptoms described above. 

What is Isovaleric Acidemia?

Isovaleric Acidemia is a type of autosomal recessive condition known as an organic acid disorder.  People with Isovaleric Acidemia have problems breaking down an amino acid called leucine from the food they eat.  This inability to breakdown proteins that contain leucine causes harmful substances to build up in their blood and urine.  The symptoms of Isovaleric Acidemia range from mild to severe.  In the severe form signs and symptoms can begin in the first days of life and include poor appetite, lethargy (extreme tiredness), vomiting, a “sweaty feet” smell, and seizures.  Early death may occur if the condition is not treated.  Children with a milder form of Isovaleric Acidemia may have failure to grow and gain weight at the typical rate and may have delayed development.  Most people with Isovaleric Acidemia need lifelong dietary and medical treatment.  However, there are rare individuals with Isovaleric Acidemia who never show symptoms. 

What causes Isovaleric Acidemia?

Isovaleric Acidemia is caused by a gene change, or mutation, in both copies of the IVD gene pair.  These mutations cause the genes to not work properly or not work at all.  The function of the IVD genes is to break down a particular building block of protein (amino acid) called leucine.  When both copies of this gene do not work correctly it leads to a toxic buildup of organic acids in the blood and causes the symptoms described above.

What is Joubert Syndrome 2/Meckel Syndrome 2?

Joubert Syndrome 2 (also known as Cerebellooculorenal Syndrome 2) is an autosomal recessive disorder that affects many parts of the body. Affected children are born with abnormalities in the parts of the brain called the cerebellum and brainstem. Signs and symptoms of Joubert Syndrome 2 begin in infancy and include rapid breathing, feeding problems, poor muscle tone, abnormal eye movements, unusual facial features, and developmental delay. Affected children have intellectual disability that ranges from mild to severe, gait problems (ataxia), vision problems, and may have seizures, liver, and/or kidney disease. Sometimes, specific mutations in the same gene cause a related autosomal recessive disorder called Meckel Syndrome 2. Signs and symptoms of Meckel Syndrome 2 include severe brain abnormalities such as encephalocele (bulging of part of the brain through an opening in the back of the skull), cysts on the liver and kidneys, extra fingers and toes, developmental delay, and intellectual disability. Some babies with Meckel Syndrome 2 also have a cleft lip and/or palate, underdeveloped eyes, and genital abnormalities. There is no cure for either of these disorders and lifespan is shortened.

What causes Joubert Syndrome 2/Meckel Syndrome 2?

Joubert Syndrome 2 and Meckel Syndrome are caused by a change, or mutation, in both copies of the TMEM216 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene pair do not work correctly, it leads to the symptoms described above. 

What is Juvenile Retinoschisis, X-Linked?

Juvenile Retinoschisis, X-Linked is an X-linked inherited condition that causes vision loss and occurs mainly in males. Males with this condition have slowly progressive loss of sight in childhood, usually identified by school age. Retinoschisis refers to the splitting of a part of the eye called the retina; this leads to progressive central vision loss from childhood to early adulthood. Vision then remains stable until 50 or 60 years of life, after which time it may significantly worsen. About half of males with this condition have loss of peripheral (side) vision. Some affected boys are unable to focus on an object (strabismus) and have involuntary eye movements (nystagmus). A small percentage of affected males will develop retinal detachment (separation of the retina) or bleeding in the blood vessels of the retina which can cause blindness.

What causes Juvenile Retinoschisis, X-Linked?

Juvenile Retinoschisis, X-Linked is caused by a change, or mutation, in the RS1 gene. This mutation causes the gene to not work properly or not work at all. The RS1 gene is important for the development and health of the retina. When this gene does not work correctly in a male, it leads to the symptoms described above.

What is Krabbe Disease?

Krabbe Disease is an autosomal recessive disorder.  It is one type of inherited condition called a leukodystrophy that affects the brain and nervous system.  Signs and symptoms usually begin in the first year of life and include irritability, poor muscle tone, stiff muscles, loss or delayed development of skills, hearing loss, vision loss, and failure to grow and gain weight at the expected rate. Symptoms worsen with time and affect swallowing and breathing, and seizures may develop.  Death usually occurs by two years of age. Some affected individuals will have onset of symptoms in later childhood or early adulthood. These individuals can have vision loss, hearing loss, stiff muscles, and problems with walking and movement. The symptoms of the later onset form vary from person to person and disease progression is slower. In some cases, individuals with Krabbe Disease have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Krabbe Disease?

Krabbe Disease is caused by a gene change, or mutation, in both copies of the GALC gene pair.  These mutations cause the gene to not work properly or not work at all. The normal function of the GALC genes is to help maintain myelin, a protective coating on the nerves in the body. When both of these genes do not work correctly, it leads to the symptoms described above. 

What is Lamellar Ichthyosis, Type 1?

Lamellar Ichthyosis, Type 1 is an autosomal recessive disorder that affects the skin.  Children with this disorder are born with a clear fitted covering over their body called a collodion membrane.  After about 10 to 14 days of life this membrane peels off, leaving skin that is covered with white or brownish scales.  Eyelids and lips may turn outward, fingernails and toenails may develop abnormally and hair loss may occur.  Affected infants may develop skin infections, dehydration, and breathing problems, and in some cases, serious joint problems.  Some infants will have improvement of their skin condition with time, and for others the skin problems may be lifelong. 

Rarely, specific mutations in the same gene pair causes a different type of ichthyosis, either ‘Self-Improving Collodion Ichthyosis’ in which affected babies are born with a collodion membrane but  typically do not have severe lifelong skin problems, or ‘Bathing Suit Ichthyosis’ in which dark gray skin scales affect only the trunk area and not the limbs or face. 

What causes Lamellar Ichthyosis, Type 1?

Lamellar Ichthyosis, Type 1 is caused by a gene change, or mutation, in both copies of the TGM1 gene pair.  These mutations cause the genes to not work properly or not work at all. The normal function of the TGM1 genes is to help in the development of the skin. When both copies of this gene do not work correctly it leads to the symptoms described above. 

What is Leber Congenital Amaurosis 2?

Leber Congenital Amaurosis 2 is an autosomal recessive disorder that causes vision loss. Eyesight problems begin in infancy. The vision loss worsens over time and by adulthood affected individuals have total blindness. Affected individuals may also have sensitivity to light, abnormal eye movements (nystagmus), and may have behavior involving repeated rubbing or pressing on the eyes with the fingers or knuckles. Cataracts and thin cornea (clear outer covering of the eye) may also be present. Very rarely, later onset of vision loss occurs, starting with loss of night vision in childhood. The vision loss progresses over time to include peripheral (side) vision, then central vision. This rare form of the disorder is called Retinitis Pigmentosa 20. Currently there is no cure for these conditions, although clinical trials of gene therapy for Leber Congenital Amaurosis 2 have shown promising results.

What causes Leber Congenital Amaurosis 2?

Leber Congenital Amaurosis 2 is caused by a gene change, or mutation, in both copies of the RPE65 gene. These mutations cause the genes to not work properly or not work at all. The normal function of the RPE65 gene is important in the development of the retina (tissue at the back of the eye that processes light and color). When both copies of this gene pair do not work correctly, it leads to the vision loss symptoms described above. 

What is Leber Congenital Amaurosis, Type CEP290?

Leber Congenital Amaurosis, Type CEP290 is an autosomal recessive disorder that causes vision loss.  Eyesight problems begin in infancy. Vision loss worsens over time and by adulthood people with this condition have total blindness.  Other symptoms may include sensitivity to light, abnormal eye movements (nystagmus), and behavior involving repeated rubbing or pressing on the eyes with the fingers or knuckles. Cataracts and thin corneas (clear outer covering of the eye) may also be present. Rarely, mutations in the same pair of genes that cause Leber Congenital Amaurosis, Type CEP290 may instead cause one of a number of related genetic disorders including Bardet-Biedl Syndrome, Joubert Syndrome, Meckel Syndrome, and Senior-Loken Syndrome. The symptoms of these conditions are similar to each other and often overlap.  Meckel Syndrome causes serious birth defects and most children do not live past infancy.  Symptoms of Bardet-Biedl and Joubert Syndrome include multiple birth defects of the brain and other organs, developmental delay and intellectual disability, vision loss, and kidney problems as well as other health problems. Senior-Loken Syndrome has the same symptoms as Leber Congenital Amaurosis but also includes kidney disease that worsens with time.

What causes Leber Congenital Amaurosis, Type CEP290?

Leber Congenital Amaurosis, Type CEP290 is caused by a gene change, or mutation, in both copies of the CEP290 gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly it leads to the symptoms described above. 

What is Leber Congenital Amaurosis, Type LCA5?

Leber Congenital Amaurosis, Type LCA5 is an autosomal recessive disorder that causes severe vision loss. Eyesight problems begin in infancy. The vision loss may stay the same or may worsen slowly over time. Affected individuals may also have sensitivity to light, abnormal eye movements (nystagmus), and may have behavior involving repeated rubbing or pressing on the eyes with the fingers or knuckles. Cataracts and thin cornea (clear outer covering of the eye) may also be present.

What causes Leber Congenital Amaurosis, Type LCA5?

Leber Congenital Amaurosis, Type LCA5 is caused by a gene change, or mutation, in both copies of the LCA5 gene pair. These mutations cause the genes to not work properly or not work at all. The normal function of the LCA5 gene is important in the development of the retina (tissue at the back of the eye that processes light and color). When both copies of this gene do not work correctly, it leads to the vision loss symptoms described above. 

What is Leber Congenital Amaurosis, Type RDH12?

Leber Congenital Amaurosis, Type RDH12 (also called Leber Congenital Amaurosis 13) is an autosomal recessive disorder that causes vision loss.  Eyesight problems begin in early childhood. The vision loss worsens over time and by adulthood people with this condition may have atotal blindness.  People with Leber Congenital Amaurosis, Type RDH12 may also have sensitivity to light, abnormal eye movements (nystagmus), and may have behavior involving repeated rubbing or pressing on the eyes with the fingers or knuckles. Cataracts and thin cornea (clear outer covering of the eye) may also be present. Very rarely, specific mutations in the same gene pair cause a different form of vision loss, called Retinitis Pigmentosa 13, causing later onset of vision loss, starting with loss of night vision in childhood. The vision loss in Retinitis Pigmentosa 13 progresses over time to include peripheral (side) vision, then central vision.  Currently there is no cure for these conditions. 

What causes Leber Congenital Amaurosis, Type RDH12?

Leber Congenital Amaurosis, Type RDH12 is caused by a gene change, or mutation, in both copies of the RDH12 gene pair.  These mutations cause the genes to not work properly or not work at all. The normal function of the RDH12 gene is important in the development of the retina (tissue at the back of the eye that processes light and color). When both copies of this gene do not work correctly, it leads to the vision loss symptoms described above. It is sometimes, but not always, possible to determine whether a specific mutation in the RDH12 gene will cause Leber Congenital Amaurosis, Type RDH12 or Retinitis Pigmentosa 13.

What is Leigh Syndrome, French-Canadian Type?

Leigh Syndrome, French-Canadian Type is an autosomal recessive disorder that affects the brain and nervous system.  Signs and symptoms begin in infancy and include developmental delay, unusual facial features, poor muscle tone, failure to grow at the expected rate, feeding problems, and abnormal movements.  Symptoms worsen with time.  Brain abnormalities may be seen on brain imaging tests such as MRI.  Affected infants can have life-threatening health problems including seizures and breathing problems.  A thickening of the heart muscle (hypertrophic cardiomyopathy) may occur.  Death often occurs in infancy or early childhood. Currently there is no cure for this condition and treatment is based on symptoms.

What causes Leigh Syndrome, French-Canadian Type?

Leigh Syndrome, French-Canadian Type is caused by a gene change, or mutation, in both copies of the LRPPRC gene pair. These mutations cause the genes to not work properly or not work at all. The normal function of the LRPPRC genes is to help make energy in the cells in the body. When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Lethal Congenital Contracture Syndrome 1?

Lethal Congenital Contracture Syndrome 1 is an autosomal recessive disorder that affects the brain, muscles, and joints. Signs and symptoms of Lethal Congenital Contracture Syndrome 1 are present before birth and include lack of muscle development, joints in the limbs that do not move, severe swelling (hydrops), and underdeveloped lungs. Most affected fetuses die before birth or are stillborn. A slightly less severe form of this condition, called Lethal Arthrogryposis with Anterior Horn Cell Disease, has similar symptoms that include lack of movement during pregnancy, stiffness of the joints, and severe breathing problems. Most infants with Lethal Arthrogryposis with Anterior Horn Cell Disease are live born but usually die in infancy due to severe breathing problems. Currently there is no cure for either form of this disorder.

What causes Lethal Congenital Contracture Syndrome 1?

Lethal Congenital Contracture Syndrome 1 is caused by a gene change, or mutation, in both copies of the GLE1 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work properly, it leads to the symptoms described above. 

What is Leukoencephalopathy with Vanishing White Matter?

Leukoencephalopathy with Vanishing White Matter is an autosomal recessive disorder that affects the brain and nervous system.  Signs and symptoms of this disorder usually begin in early childhood and begin with difficulty with movement and coordination and loss of developmental milestones that worsen over time.  Affected children can have stiff muscles, seizures, and intellectual disability.  A severe increase in symptoms can happen after mild head injury.  “Vanishing white matter” refers to the progressive loss of brain tissue that can be seen on brain imaging tests such as MRI in people with this condition.  The severe form of this condition has symptoms that start in infancy and leading to death in infancy or early childhood.  Some people may have a milder form with symptoms beginning in adolescence. Psychiatric problems are more common in later onset forms.   

What causes Leukoencephalopathy with Vanishing White Matter?

Leukoencephalopathy with Vanishing White Matter is caused by a gene change, or mutation, in both copies of the EIF2B5 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the EIF2B5 gene pair do not work correctly, it leads to the symptoms described above.

What is Limb-Girdle Muscular Dystrophy, Type 2A?

Limb-Girdle Muscular Dystrophy, Type 2A is autosomal recessive and one of a group of inherited disorders that affect the muscles of the hips and shoulders. Over time, Limb-Girdle Muscular Dystrophy, Type 2A causes weakness and breakdown (atrophy) of the pelvic, hip, thigh, shoulder, and upper arm muscles. Onset of symptoms varies between age 2 to age 40, but often starts in adolescence or early adulthood. Muscle weakness leads to difficulty in walking, running, and getting up from the floor.  The muscle weakness usually worsens very slowly with age.  Over time, some people with this condition need the use of a wheelchair. Currently, there is no cure for this condition and treatment is based on symptoms.

What causes Limb-Girdle Muscular Dystrophy, Type 2A?

Limb-Girdle Muscular Dystrophy, Type 2A is caused by a gene change, or mutation, in both copies of the CAPN3 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene are not working correctly, it leads to the symptoms described above.

What is Limb-Girdle Muscular Dystrophy, Type 2B?

Limb-Girdle Muscular Dystrophy, Type 2B is autosomal recessive.  It is one of a group of autosomal recessive disorders that affect the muscles of the hips and shoulders. Limb-Girdle Muscular Dystrophy, Type 2B causes progressive weakness and breakdown (atrophy) of the pelvic, hip, thigh, shoulder, and upper arm muscles. Onset of symptoms varies but usually starts in adolescence or early adulthood. Muscle weakness usually worsens very slowly with age and leads to problems in walking, running, and getting up from the floor.  Over time, some people with this condition need the use of a wheelchair. Currently, there is no cure for this condition and treatment is based on symptoms. Rarely, mutations in the same pair of genes that cause Limb-Girdle Muscular Dystrophy, Type 2B instead cause a related disorder, either Miyoshi Myopathy or Distal Myopathy with Anterior Tibial Onset.  Miyoshi Myopathy is most common in people of Japanese ancestry and causes progressive weakness and wasting of the leg and arm muscles, with leg muscles being more severely affected.  Distal Myopathy with Anterior Tibial Onset includes progressive weakness of the leg muscles, beginning with the lower leg muscles and later the upper leg muscles, eventually leading to the need for a wheelchair. 

What causes Limb-Girdle Muscular Dystrophy, Type 2B?

Limb-Girdle Muscular Dystrophy, Type 2B is caused by a gene change, or mutation, in both copies of the DYSF gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Limb-Girdle Muscular Dystrophy, Type 2C?

Limb-Girdle Muscular Dystrophy, Type 2C is autosomal recessive and one of a group of inherited disorders that affect the muscles of the hips and shoulders.  Over time, Limb-Girdle Muscular Dystrophy, Type 2C leads to weakness and breakdown (atrophy) of the pelvic, hip, thigh, shoulder, and upper arm muscles. Symptoms vary from person to person but usually begin in childhood and worsen slowly over many years. Muscle weakness and atrophy lead to difficulty in walking, running, and getting up from the floor. Over time, some people with this condition need the use of a wheelchair.  Problems with the joints and the heart and breathing difficulties may also occur.  Currently there is no cure for this condition and treatment is based on symptoms.

What causes Limb-Girdle Muscular Dystrophy, Type 2C?

Limb-Girdle Muscular Dystrophy, Type 2C is caused by a gene change, or mutation, in both copies of the SGCG gene pair.  These mutations cause the genes to not work properly or not work at all.  Normal function of the SGCG genes is important for healthy muscle development. When both copies of the SGCG gene do not work correctly, it leads to the symptoms described above. 

What is Limb-Girdle Muscular Dystrophy, Type 2D?

Limb-Girdle Muscular Dystrophy, Type 2D is autosomal recessive and one of a group of inherited disorders that affect the muscles of the hips and shoulders.  Over time, Limb-Girdle Muscular Dystrophy, Type 2D leads to weakness and breakdown (atrophy) of the pelvic, hip, thigh, shoulder, and upper arm muscles. Symptoms vary from person to person but usually begin in childhood or early adulthood and worsen slowly over many years. Muscle weakness and atrophy lead to difficulty in walking, running, and getting up from the floor. Over time, some people with this condition need the use of a wheelchair.  Less commonly, problems with the joints and the heart and breathing difficulties may occur.  Currently there is no cure for this condition and treatment is based on symptoms.

What causes Limb-Girdle Muscular Dystrophy, Type 2D?

Limb-Girdle Muscular Dystrophy, Type 2D is caused by a gene change, or mutation, in both copies of the SGCA gene pair.  These mutations cause the genes to not work properly or not work at all.  Normal function of the SGCA gene is important for healthy muscle development. When both copies of the SGCA gene do not work correctly, it leads to the symptoms described above. 

What is Limb-Girdle Muscular Dystrophy, Type 2E?

Limb-Girdle Muscular Dystrophy, Type´ 2E is autosomal recessive and one of a group of inherited disorders that affect the muscles of the hips and shoulders.  Over time, Limb-Girdle Muscular Dystrophy, Type 2E leads to weakness and breakdown (atrophy) of the pelvic, hip, thigh, shoulder, and upper arm muscles. Symptoms vary from person to person but usually begin in childhood or early adulthood and worsen slowly over many years. Muscle weakness and atrophy lead to difficulty in walking, running, and getting up from the floor.  Over time, some people with this condition need the use of a wheelchair.  Less commonly, problems with the joints and the heart and breathing difficulties may occur.  Currently there is no cure for this condition and treatment is based on symptoms.

What causes Limb-Girdle Muscular Dystrophy, Type 2E?

Limb-Girdle Muscular Dystrophy, Type 2E is caused by a gene change, or mutation, in both copies of the SGCB gene pair.  These mutations cause the genes to not work properly or not work at all.  Normal function of the SGCB genes is important for healthy muscle development.  When both copies of the SGCB gene pair do not work correctly, it leads to the symptoms described above. 

What is Limb-Girdle Muscular Dystrophy, Type 2I?

Limb-Girdle Muscular Dystrophy, Type 2I is autosomal recessive.  It is one of a group of autosomal recessive disorders that affect the muscles of the hips and shoulders.  Over time, Limb-Girdle Muscular Dystrophy Type 2I leads to weakness and breakdown (atrophy) of the pelvic, hip, thigh, shoulder, and upper arm muscles. Symptoms vary from person to person but usually begin in childhood or early adulthood and worsen slowly over many years. Muscle weakness and atrophy lead to difficulty in walking, running, and getting up from the floor.  Over time, some people with this condition need the use of a wheelchair.  As the disease progresses, kidney, heart, and joint problems, as well as breathing difficulties may occur. 

Less often, mutations in the same pair of genes cause a related but more severe disorder called Walker-Warburg Syndrome.  Walker-Warburg Syndrome causes abnormalities of the brain and eyes along with severe muscle weakness that begins in infancy.  Babies with this condition who have brain abnormalities usually do not live past early childhood.  Some children do not have the brain and eye abnormalities and may live longer, although life span is still shortened.  Currently there is no cure for these conditions and treatment is based on symptoms.

What causes Limb-Girdle Muscular Dystrophy, Type 2I?

Limb-Girdle Muscular Dystrophy, Type 2I is caused by a gene change, or mutation, in both copies of the FKRP gene pair.  These mutations cause the genes to not work properly or not work at all.  Normal function of the FKRP gene is important for healthy muscle development.  When both copies of the FKRP gene pair do not work correctly, it leads to the symptoms described above.  It is sometimes, but not always, possible to determine whether a specific mutation in the FKRP gene will cause Limb-Girdle Muscular Dystrophy, Type 2I or Walker-Warburg Syndrome.

What is Lipoamide Dehydrogenase Deficiency (Dihydrolipoamide Dehydrogenase Deficiency)?

Lipoamide Dehydrogenase Deficiency (also known as Dihydrolipoamide Dehydrogenase Deficiency or Maple Syrup Urine Disease Type 3) is an autosomal recessive disorder that causes the buildup of a toxic substance called lactic acid in the body. Symptoms often begin between one and six months of age and include rapid breathing and heartbeat, nausea and vomiting, low muscle tone (hypotonia), abnormal movements, lack of energy, and poor growth that sometimes leads to early death. Infants and children with Lipoamide Dehydrogenase Deficiency who survive often have developmental delay, intellectual disability, stiff muscles (spasticity), abnormal movements, and seizures. A special medical diet, supplements, and other medical treatments are used to try to slow down the progression of the symptoms but there is no cure. A less common form of this condition causes only liver disease which can progress over time to liver failure; symptoms can start as early as birth but often start later in adulthood.

What causes Lipoamide Dehydrogenase Deficiency (Dihydrolipoamide Dehydrogenase Deficiency)?

Lipoamide Dehydrogenase Deficiency is caused by a gene change, or mutation, in both copies of the DLD gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene are not working correctly, it leads to the symptoms described above.

What is Lipoid Adrenal Hyperplasia?

Lipoid Adrenal Hyperplasia is a rare autosomal recessive disorder in which the adrenal glands cannot make certain steroid hormones. There are two forms of Lipoid Adrenal Hyperplasia; a classic form and a non-classic form. In the classic form, life-threatening symptoms begin within the first few months of life if not treated.  The lack of adrenal hormones causes severe salt loss in the urine, leading to dehydration and death unless hormone replacement is started.  Males with the classic form are born with external genitals that look female. This is caused by problems with sex hormone production. In the non-classic form, symptoms are less severe and start later in infancy or childhood and do not show the genital changes seen in the classic form.  Medical treatment with hormone replacement may help prevent or reduce symptoms of this condition.

What causes Lipoid Adrenal Hyperplasia?

Lipoid Adrenal Hyperplasia is caused by a gene change, or mutation, in both copies of the STAR gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the STAR gene do not work correctly, the body cannot make specific steroid hormones, leading to the symptoms described above.

What is Lipoprotein Lipase Deficiency?

Lipoprotein Lipase Deficiency is an autosomal recessive disorder in which the body either cannot make, or makes less of, an enzyme called lipoprotein lipase. Without normal amounts of this enzyme, the body cannot break down fat from food, which causes fat to build up in the blood. Symptoms of Lipoprotein Lipase Deficiency usually begin in childhood with episodes of abdominal pain, abnormally high levels of triglycerides (a form of fat) in the blood, enlarged spleen and liver, inflammation of the pancreas, and raised areas of fat under the of skin (xanthomas).  Treatment with a very low fat diet can prevent or lessen the symptoms. 

What causes Lipoprotein Lipase Deficiency?

Lipoprotein Lipase Deficiency is caused by a gene change, or mutation, in both copies of the LPL gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the LPL gene do not work correctly, it leads to the symptoms described above.

Carriers for Lipoprotein Lipase Deficiency may have a moderate increase in triglyceride levels which may give them a slightly increased risk for early atherosclerosis. 

What is Long Chain 3-Hydroxyacyl-CoA Dehydrogenase Deficiency?

Long Chain 3-Hydroxyacyl-CoA Dehydrogenase (LCHAD) Deficiency is an autosomal recessive disorder in which the body cannot break down and use certain fats for energy.  Signs and symptoms of LCHAD Deficiency typically appear during infancy or early childhood and can include vomiting, lack of energy, weak muscle tone, and low blood sugar (hypoglycemia). The symptoms of LCHAD Deficiency are often triggered by going a long time without eating (fasting) or during illness. If the condition is not treated, children with LCHAD Deficiency are at risk for breathing problems, intellectual disability, enlarged heart and liver, vision loss, seizures, coma, and sudden death. Treatment includes a medical low-fat diet, avoidance of fasting, and other supplements that help prevent or lessen the symptoms. Even with careful treatment, some children still have repeated episodes of low blood sugar and other long-term health problems.

Rarely, mutations in the same gene pair cause a related disorder called Mitochondrial Trifunctional Protein Deficiency.  This disorder has similar symptoms to LCHAD Deficiency with similar treatment. There is an early-onset severe form that sometimes results in death, even with treatment; a childhood-onset form that needs lifelong treatment; and a rare milder form that causes muscle breakdown leading to cramping, weakness, pain, and red-brown colored urine but does not affect intelligence.

What causes Long Chain 3-Hydroxyacyl-CoA Dehydrogenase Deficiency?

Long Chain 3-Hydroxyacyl-CoA Dehydrogenase (LCHAD) Deficiency is caused by a gene change, or mutation, in both copies of the HADHA gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

Women who are carriers for LCHAD Deficiency or Mitochondrial Trifunctional Protein Deficiency and are pregnant with an affected fetus are at risk to develop serious liver disorders called AFLP (acute fatty liver of pregnancy) and HELLP Syndrome (hemolysis, elevated liver enzymes, low platelets).  Signs and symptoms include pain in the abdomen, low blood sugar, ammonia in the blood, breakdown of red blood cells, and abnormal liver enzymes. 

What is Lysinuric Protein Intolerance?

Lysinuric Protein Intolerance is an autosomal recessive disorder in which certain building blocks of protein (amino acids) cannot be broken down correctly by the body. This leads to a toxic buildup of ammonia in the blood. Symptoms of Lysinuric Protein Intolerance usually first begin in infancy after the baby is weaned off breast milk or formula and starts eating solid food. Symptoms include nausea, vomiting, poor feeding and poor growth, aversion to protein-rich foods, poor muscle tone, brittle bones, enlarged liver and spleen, and lung and kidney problems. Treatment with a medical low-protein diet along with specific supplements and medications can lessen the severity of symptoms but cannot prevent them.

What causes Lysinuric Protein Intolerance?

Lysinuric Protein Intolerance is caused by a gene change, or mutation, in both copies of the SLC7A7 gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Maple Syrup Urine Disease, Type 1A?

Maple Syrup Urine Disease, Type 1A is an autosomal recessive disorder in which the body is unable to break down certain building blocks of protein from food.  Signs and symptoms usually begin in infancy and include poor feeding, vomiting, lack of energy, failure to grow at the normal rate, and developmental delay. Maple Syrup Urine Disease gets its name from the maple syrup odor of the urine in babies with the disease.   Symptoms may worsen after going a long time without food or with illness and can be life-threatening.  Lifelong dietary treatment is needed.  If untreated, Maple Syrup Urine Disease, Type 1A can lead to intellectual disability, seizures, coma, and sometimes death.  Even with treatment affected children continue to have symptoms of the disorder.  Some children have a milder form of Maple Syrup Urine Disease, Type 1A with fewer symptoms. 

What causes MSUD, Type 1A?

Maple Syrup Urine Disease, Type 1A is caused by a change, or mutation, in both copies of the BCKDHA gene pair.  These mutations cause the genes to not work properly or not work at all.  The function of the BCKDHA genes is to help breakdown certain building blocks of protein in food called amino acids.  When both copies of this gene pair do not work correctly, toxic buildup of certain amino acids occurs and causes damage to the brain and other organs. 

What is Maple Syrup Urine Disease, Type 1B?

Maple Syrup Urine Disease, Type 1B is an autosomal recessive disorder in which the body is not able to break down certain building blocks of protein (amino acids) from food.  Signs and symptoms usually begin in infancy and include poor feeding, vomiting, lack of energy, failure to grow at the normal rate, and developmental delay.  Maple Syrup Urine Disease gets its name from the maple syrup odor of the urine in babies with the disease.  Symptoms may worsen after going a long time without food or with illness and can be life-threatening.  Lifelong dietary and medical treatment is needed.  If untreated, Maple Syrup Urine Disease, Type 1B can lead to intellectual disability, seizures, coma, and sometimes death.  Even with treatment some children continue to have symptoms of the disorder.  Some children have a milder form of Maple Syrup Urine Disease, Type 1B with fewer symptoms. 

What causes Maple Syrup Urine Disease, Type 1B?

Maple Syrup Urine Disease, Type 1B is caused by a gene change, or mutation, in both copies of the BCKDHB gene pair. These mutations cause the genes to not work properly or not work at all.  The function of the BCKDHB genes is to help breakdown certain building blocks of protein in food called amino acids.  When both copies of this gene pair do not work correctly, toxic buildup of certain amino acids occurs and causes damage to the brain and other organs. 

What is Meckel-Gruber Syndrome, Type 1?

Meckel-Gruber Syndrome, Type 1 (also called Meckel Syndrome, Type 1) is an autosomal recessive disorder that causes birth defects in many parts of the body.  Affected infants have an encephalocele (bulging of part of the brain through an opening in the back of the skull), small head with sloping forehead, abnormal kidneys with many cysts (fluid-filled sacs), and extra fingers and toes.  Affected babies may also have other birth defects including cleft lip and/or cleft palate, underdeveloped eyes, liver abnormalities, and underdeveloped or abnormal genitals.  There is no cure for Meckel-Gruber Syndrome, Type 1 and most babies die shortly after birth due to the severity of the health problems associated with this disorder.

Rarely, mutations in the same gene pair cause one of two related disorders, either Bardet-Biedl Syndrome 13, or, even less often, Joubert Syndrome 28. 

What causes Meckel-Gruber Syndrome, Type 1?

Meckel-Gruber Syndrome, Type 1 is caused by a gene change, or mutation, in both copies of the MKS1 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the MKS1 gene pair do not work correctly, it leads to the symptoms described above. 

What is Medium Chain Acyl-CoA Dehydrogenase Deficiency?

Medium Chain Acyl-CoA Dehydrogenase Deficiency is an autosomal recessive disorder that causes the body to be unable to break down certain types of fat. It is one of a group of inherited conditions called fatty acid oxidation disorders.  Children born with Medium Chain Acyl-CoA Dehydrogenase Deficiency are unable to change some of the fats from food that they eat into energy that the body needs to function properly. As a result, fatty acids build up in the body.  If left untreated, this disorder can lead to health problems such as seizures, breathing problems, liver problems, brain damage, coma, and even death.  With diagnosis and treatment early in life, people with Medium Chain Acyl-CoA Dehydrogenase Deficiency can often lead healthy lives.  Some people with Medium Chain Acyl-CoA Dehydrogenase Deficiency have milder symptoms or no symptoms at all.

What causes Medium Chain Acyl-CoA Dehydrogenase Deficiency?

Medium Chain Acyl-CoA Dehydrogenase Deficiency is caused by a gene change, or mutation in both copies of the ACADM gene pair.  These mutations cause the genes to not work properly or not work at all.  The function of the ACADM genes is to make an enzyme called medium-chain acyl-CoA dehydrogenase, which is needed to break down a type of fat, called medium-chain fatty acids, found in food and the body’s fat stores.  When both copies of this gene do not work correctly, it can lead to the symptoms described above.

What is Megalencephalic Leukoencephalopathy with Subcortical Cysts?

Megalencephalic Leukoencephalopathy with Subcortical Cysts is an autosomal recessive disorder that affects the brain and nervous system. Signs and symptoms begin in infancy or childhood and include large head and brain size, developmental delays, loss of developmental skills, problems with coordination and movement, muscle stiffness, seizures, speech problems, and mild to moderate intellectual disability. Some people with this condition can walk without assistance and others eventually need a wheelchair.   Currently there is no cure for this disorder and treatment is based on symptoms.

What causes Megalencephalic Leukoencephalopathy with Subcortical Cysts?

Megalencephalic Leukoencephalopathy with Subcortical Cysts is caused by a gene change, or mutation, in both copies of the MLC1 gene pair. These mutations cause the genes to not work properly or not work at all. Normal function of the MLC1 genes is important for development of the brain and nerves. When both copies of the MLC1 gene do not work correctly, it leads to the symptoms described above. 

What is Menkes Syndrome?

Menkes Syndrome is a severe X-linked inherited disorder that affects mainly boys. Signs and symptoms often start in infancy and include sparse light-colored and kinky hair, lax skin, growth delays, poor muscle tone (hypotonia), bladder infections, seizures, developmental delay, intellectual disability, breathing problems, and strokes. Currently there is no cure for Menkes Syndrome. Treatment with copper supplements can help lessen the symptoms in some children with Menkes; however, even with careful treatment, many children do not live beyond 3 years of age.

Rare individuals have a milder form of Menkes Syndrome sometimes called Occipital Horn Syndrome or X-Linked Cutis Laxa. Signs and symptoms of Occipital Horn Syndrome usually begin in childhood and include calcified wedges near the back of the head (occipital horns), lax skin, flexible joints, hernias, twisted blood vessels, and chronic diarrhea. Some people with Occipital Horn Syndrome have mild intellectual disability. Lifespan may be shortened but most people live until adulthood. Even more rarely, a different form of the disorder, called ATP7A-Related Distal Motor Neuropathy (or Spinal Muscular Atrophy, Distal, X-Linked 3), may occur. Symptoms of Distal Motor Neuropathy usually begin in adulthood but may appear earlier in childhood and include worsening muscle weakness and wasting (atrophy) of the hands and feet, difficulty walking, lack of reflexes in the ankles, and lack of sensation in the fingers and toes. Other symptoms may include hammer toes, curled fingers, and an abnormally high arch of the foot (pes cavus).

What causes Menkes Syndrome?

Menkes Syndrome is caused by a change, or mutation, in the ATP7A gene, which causes the gene to not work properly or not work at all. When this gene does not work correctly in a male, it leads to Menkes Syndrome or one of the rare related disorders described above. 

What is Metachromatic Leukodystrophy, ARSA-Related?

Metachromatic Leukodystrophy (MLD), ARSA-Related is an autosomal recessive disorder that affects the brain and nervous system.  MLD, ARSA-Related causes a buildup of a specific type of fat in the cells of the body.  This causes myelin, the substance that covers and protects nerves, to break down over time.  Without myelin, brain and nerve cells no longer work properly. There are 3 forms of MLD, ARSA-Related: the late infantile form usually shows symptoms by age 2; the juvenile form starts ina childhood or early adolescence; and the adult form starts in young adulthood.  Symptoms of MLD, ARSA-Related include loss of cognitive and motor skills, behavior and personality changes, seizures, dementia, and loss of hearing, vision, and speech, all of which worsen over time. The condition eventually leads to paralysis and loss of responsiveness. Lifespan is shortened, especially with the early-onset forms. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Metachromatic Leukodystrophy, ARSA-Related?

MLD, ARSA-Related is caused by a gene change, or mutation, in both copies of the ARSA gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Metachromatic Leukodystrophy, PSAP-Related?

Metachromatic Leukodystrophy, PSAP-Related is an autosomal recessive disorder that affects many parts of the body. Signs and symptoms usually begin in childhood. Symptoms include anemia, easy bruising, fatigue, bone problems including bone pain and breaks, enlarged liver and spleen, and lung disease. Some children will also have symptoms involving the brain and nervous system including seizures, developmental delays, intellectual disability, abnormal eye movements, and problems with coordination and movement. The symptoms may worsen over time. In rare cases, symptoms do not begin until adolescence or adulthood. In some cases, individuals with Metachromatic Dystrophy, PSAP-Related have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

Very rarely, mutations in the same gene cause a related disorder, either Gaucher Disease, atypical, Krabbe Disease, atypical, or Combined SAP Deficiency. Symptoms of these disorders include a severely enlarged liver and spleen along with brain and nervous system problems that are similar to or more severe than those described above. Babies with either Krabbe Disease, atypical or Combined SAP Deficiency have very severe symptoms starting from birth and usually die in infancy or early childhood. People with Gaucher Disease, atypical may start having symptoms in childhood or not until early adulthood.

What causes Metachromatic Leukodystrophy, PSAP-Related?

Metachromatic Leukodystrophy, PSAP-Related is caused by a gene change, or mutation, in both copies of the PSAP gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the PSAP gene do not work correctly, it leads to the symptoms described above.

What is Methylmalonic Aciduria and Homocystinuria, Type cblC?

Methylmalonic Aciduria refers to a group of autosomal recessive conditions with many different forms, each of which has different causes and treatments. The type described here is Methylmalonic Aciduria and Homocystinuria, Type cblC. In this disorder, the body is not able to use vitamin B12 (cobalamin) correctly to break down certain types of fat and protein from food.  Symptoms of Methylmalonic Aciduria and Homocystinuria, Type cblC usually begin in the first month of life and can include growth delay, small head size, skin rash, vomiting, feeding problems, fever, lethargy (extreme tiredness), weak muscle tone (hypotonia), and vision loss due to damage to the retina.  Lifelong dietary and medical treatments are needed for this disorder.  If left untreated, death in infancy or childhood may occur.  Some people with this disorder have a milder form with onset in adulthood. 

What causes Methylmalonic Aciduria and Homocystinuria, Type cblC?

Methylmalonic Aciduria and Homocystinuria, Type cblC is caused by a gene change or mutation in both copies of the MMACHC gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, the body cannot use Vitamin B12 properly to break down certain fats and proteins in the diet.  This causes a toxic buildup of the amino acids methylmalonic acid and homocysteine in the body, which causes the symptoms described above.

What is Methylmalonic Aciduria and Homocystinuria, Type cblD?

Methylmalonic Aciduria refers to a group of autosomal recessive conditions with many different forms, each of which has different causes and treatments. The type described here is Methylmalonic Aciduria and Homocystinuria, Type cblD.  In this disorder, the body cannot use vitamin B12 (cobalamin) correctly to break down certain types of fat and protein from food.  This causes the buildup of toxic substances in the blood and can lead to serious health problems. Symptoms include small head size, poor appetite and growth, lack of energy, low muscle tone (hypotonia), eye abnormalities, developmental delay, anaemia, neurological problems, seizures, and intellectual deficit. Symptoms vary and can begin before birth or not until adulthood. In most cases, symptoms start in infancy and often become worse after going a long time without food or during illness.  Some children have symptoms of either Homocystinuria or Methylmalonic Acidemia but not both. For some children, medical treatment including vitamin B12 injections, other supplements, and a special diet may help reduce the severity of this disorder.

What causes Methylmalonic Aciduria and Homocystinuria, Type cblD?

Methylmalonic Aciduria and Homocystinuria, Type cblD is caused by a change, or mutation, in both copies of the MMADHC gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, the body cannot use Vitamin B12 properly to break down certain fats and proteins in the diet.  This causes a toxic buildup of the amino acids methylmalonic acid and/or homocysteine the body, which causes the symptoms described above.

What is Methylmalonic Aciduria, MMAA-Related?

Methylmalonic Aciduria refers to a group of autosomal recessive disorders in which the body cannot break down certain proteins and fats from food.  This leads to the lack of energy for the body and a buildup of toxic substances in the blood. There are many forms of this Methylmalonic Aciduria, each caused by mutations in a different gene, one of which is MMAA. Symptoms of Methylmalonic Aciduria, MMAA-Related usually start in infancy or childhood and often include episodes of feeding and breathing problems, vomiting, weak muscle tone, and lack of energy. Episodes often start during illness or stress, going a long time without food, or eating too much protein.  If these episodes are not treated, they can lead to seizures, stroke, or coma and can sometimes be life-threatening. Children with this condition may also have slow weight gain and growth, and developmental delay. Methylmalonic Aciduria, MMAA-Related is sometimes referred to as ‘vitamin B12 responsive’, meaning that it can often be treated with vitamin B12 injections. Vitamin B12, along with a special diet and other medical treatments, can help prevent further symptoms but cannot correct any problems that have already occurred.

What causes Methylmalonic Aciduria, MMAA-Related?

Methylmalonic Aciduria, MMAA-Related is caused by a change, or mutation, in both copies of the MMAA gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Methylmalonic Aciduria, MMAB-Related?

Methylmalonic Aciduria refers to a group of autosomal recessive disorders in which the body cannot break down certain proteins and fats from food.  This leads to the lack of energy for the body and a buildup of toxic substances in the blood. There are many forms of this disorder, each caused by mutations in a different gene, one of which is MMAB. Symptoms of Methylmalonic Aciduria, MMAB-Related usually start in infancy or childhood and may include episodes of breathing problems, feeding problems and vomiting, weak muscle tone, and lack of energy.  Episodes often start during illness or stress, going a long time without food, or eating too much protein.  If these episodes are not treated, they can lead to seizures, stroke, or coma and can sometimes be life-threatening. Children with this condition may also have slow weight gain and growth, and developmental delay. Methylmalonic Aciduria, MMAB-Related is sometimes referred to as ‘vitamin B12 responsive’, meaning that it can sometimes be treated with vitamin B12 injections. Vitamin B12, along with a special diet and other medical treatments, may help prevent further symptoms in some children but cannot correct any problems that have already occurred.

What causes Methylmalonic Aciduria, MMAB-Related?

Methylmalonic Aciduria, MMAB-Related is caused by a change, or mutation, in both copies of the MMAB gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Methylmalonic Aciduria, Type mut(0)?

Methylmalonic Aciduria refers to a group of autosomal recessive disorders in which the body cannot break down certain proteins and fats from food.  This leads to the lack of energy for the body and a buildup of toxic substances in the blood. There are many forms of this disorder, each caused by mutations in a different gene, one of which is MUT.  Methylmalonic Aciduria, Type mut(0), is the most common and severe form with symptoms usually first starting in infancy.  Infants quickly start to show symptoms of vomiting, dehydration, breathing problems, and lack of energy.  Other symptoms that develop over time include enlarged liver, weak muscle tone, feeding problems, intellectual disability, kidney disease, and inflammation of the pancreas (pancreatitis). Without treatment, Methylmalonic Aciduria, Type mut(0) can be life-threatening. Treatment can sometimes reduce the severity of symptoms, but there is no cure for this disorder.

What causes Methylmalonic Aciduria, Type mut(0)?

Methylmalonic Aciduria, Type mut(0)  is caused by a change, or mutation, in both copies of the MUT gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the MUT gene do not work correctly, it leads to the symptoms described above.

What is Microphthalmia/Anophthalmia, VSX2-Related?

Microphthalmia/Anophthalmia, VSX2-Related is an autosomal recessive disorder that causes specific birth defects of the eyes. Microphthalmia is when one or both eyes are smaller than average at birth and vision is impaired. Anophthalmia is when one or both eyes are absent at birth and there is no vision. An infant can be born with microphthalmia in one eye and anophthalmia in the other eye, the same type of birth defect in both eyes, or have just one affected eye. Children with this disorder may also have other abnormalities of the eye including cataracts, cysts, abnormalities of the cornea, and colobomas (a birth defect in the lens, iris, or retina).

What causes Microphthalmia/Anophthalmia, VSX2-Related?

Microphthalmia/Anophthalmia, VSX2-Related is caused by a change, or mutation, in both copies of the VSX2 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Mitochondrial Complex 1 Deficiency, ACAD9-Related?

Mitochondrial Complex 1 Deficiency, ACAD9-Related (also called Acyl-Coenzyme Dehydrogenase 9 Deficiency or Riboflavin-Responsive Complex 1 Deficiency) is an inherited disorder that causes repeated episodes of metabolic acidosis, a condition in which the blood becomes very acidic. Signs and symptoms vary from person to person but often start in infancy and include bouts of metabolic acidosis that can lead to swelling of the brain, vomiting, seizures, coma, and sometimes death. Children with the severe form of this condition who survive may have ongoing heart problems, liver failure, muscle weakness, and coordination problems. Some children have less severe symptoms that start later in childhood and include a general lack of energy and extreme tiredness after exercise. Although there is no cure for this condition, treatment with high doses of Vitamin B2 (Riboflavin) may be helpful in preventing or reducing some of the symptoms.

What causes Mitochondrial Complex 1 Deficiency, ACAD9-Related?

Mitochondrial Complex 1 Deficiency, ACAD9-Related is caused by a gene change, or mutation, in both copies of the ACAD9 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Mitochondrial Complex 1 Deficiency, NDUFAF5-Related?

Mitochondrial Complex 1 Deficiency, NDUFAF5-Related is an autosomal recessive disorder that causes abnormal function of the mitochondria, the energy-producing structures found in the cells of the body.  Symptoms can start in infancy, childhood, or not until later in adulthood.  Common symptoms include larger than normal head size, progressive loss of the white matter of the brain, delayed development, seizures, enlarged heart, vision loss, liver disease, kidney disease, muscle disease, and abnormal movements. Infants who show symptoms early in life usually have more severe disease and may have a shortened lifespan.

What causes Mitochondrial Complex 1 Deficiency, NDUFAF5-Related?

Mitochondrial Complex 1 Deficiency, NDUFAF5-Related is caused by a change, or mutation, in both copies of the NDUFAF5 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Mitochondrial Complex 1 Deficiency, NDUFS6-Related?

Mitochondrial Complex 1 Deficiency, NDUFS6-Related is an autosomal recessive disorder that causes abnormal function of the mitochondria, the energy-producing structures found in the cells of the body.  Symptoms can start in infancy, childhood, or not until later in adulthood.  Common symptoms include larger than normal head size, progressive loss of the white matter of the brain, seizures, enlarged heart, vision loss, liver disease, kidney disease, muscle disease, and abnormal movements. Infants who show symptoms early in life usually have more severe disease and may have a shortened lifespan.

What causes Mitochondrial Complex 1 Deficiency, NDUFS6-Related?

Mitochondrial Complex 1 Deficiency, NDUFS6-Related is caused by a change, or mutation, in both copies of the NDUFS6 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Mitochondrial Myopathy and Sideroblastic Anemia (MLASA1)?

Mitochondrial Myopathy and Sideroblastic Anemia, also known as Myopathy, Lactic Acidosis, and Sideroblastic Anemia 1 (MLASA1) is an autosomal recessive disorder that causes extreme fatigue, breathing problems, muscle weakness with exercise (exercise intolerance), and a specific type of anemia known as sideroblastic anemia. Exercise intolerance often begins in childhood and worsens over time. Sideroblastic anemia, in which the bone marrow makes abnormally shaped red blood cells that have trouble carrying enough oxygen to the cells of the body, usually begins in adolescence. Delayed growth, facial abnormalities, and intellectual disability occur in some people but are less common.

What causes Mitochondrial Myopathy and Sideroblastic Anemia (MLASA1)?

Mitochondrial Myopathy and Sideroblastic Anemia (MLASA1) is caused by a change, or mutation, in both copies of the PUS1 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Mucolipidosis II/IIIA?

Mucolipidosis II/IIIA, also known as I-cell Disease or Pseudo-Hurler Polydystrophy, refers to two related autosomal recessive disorders that affect many parts of the body.  Signs and symptoms of Mucolipidosis II begin in infancy and include short stature, developmental delay, abnormalities of the bones and joints, and heart disease. Other symptoms may include recurrent respiratory and ear infections, breathing problems, vision problems, hearing loss, hernias, carpal tunnel syndrome, and thickened skin. Children lose developmental skills over time, symptoms worsen, and death usually occurs in childhood. In some cases, individuals with Mucolipidosis II have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual. Signs and symptoms of Mucolipidosis IIIA usually begin in early childhood and are milder than those of Mucolipidosis II.  Lifespan may be normal in individuals with Mucolipidosis IIIA and rare affected individuals do not show symptoms until adulthood.

What causes Mucolipidosis II/IIIA?

Mucolipidosis II/IIIA is caused by a gene change, or mutation, in both copies of the GNPTAB gene pair. These mutations cause the genes to not work properly or not work at all. Normal function of the GNPTAB gene pair is needed to break down and get rid of waste in the cells of the body. When both copies of the GNPTAB gene do not work correctly, it leads to the symptoms described above. 

What is Mucolipidosis III gamma?

Mucolipidosis III gamma is an autosomal recessive disorder that affects many parts of the body.  Signs and symptoms of Mucolipidosis type III gamma usually begin by the age of 3 and include short stature, unusual facial features, abnormalities and pain in the bones and joints, and heart disease. Some affected children have mild intellectual disability.  Symptoms worsen over time.  Most people with this condition live until adulthood but lifespan may be shortened.  Currently there is no cure for this condition and treatment is based on symptoms.

What causes Mucolipidosis III gamma?

Mucolipidosis III gamma is caused by a gene change, or mutation, in both copies of the GNPTG gene pair. These mutations cause the genes to not work properly or not work at all. Normal function of the GNPTG gene pair is needed to break down certain substances in the cells of the body. When both copies of the GNPTG gene do not work correctly, it leads to the symptoms described above. 

What is Mucolipidosis, Type IV?

Mucolipidosis, Type IV is an autosomal recessive disorder in which affected infants and children have motor delay, severe intellectual disability, and vision problems that worsen over time.  Other common symptoms include weak muscle tone (hypotonia), problems eating and swallowing, limited speech, and problems with movement, especially of the hands.  Lifespan may be shortened although most people with this condition live into adulthood.  A small number of people with Mucolipidosis, Type IV have milder symptoms.  Currently there is no cure for this condition and treatment is based on symptoms.

What causes Mucolipidosis, Type IV?

Mucolipidosis, Type IV is caused by a gene change, or mutation, in both copies of the MCOLN1 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Mucopolysaccharidosis, Type I (Hurler Syndrome)?

Mucopolysaccharidosis, Type I, also known as Hurler syndrome, is an autosomal recessive disorder that causes toxic buildup of certain types of sugars, called glycosaminoglycans, in the body.  There are mild and severe forms of Mucopolysaccharidosis, Type I.  Most children with Mucopolysaccharidosis, Type I have symptoms in the first years of life that may include progressive intellectual disability, large head size, coarse facial features, heart problems, bone problems, short stature, enlarged liver and spleen, frequent infections, vision problems, and breathing problems. Without treatment, children with this form of Mucopolysaccharidosis, Type I usually do not survive past childhood.  People with milder forms of this disorder usually live into adulthood and have a milder degree of intellectual disability. Treatment may include enzyme replacement therapy. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Mucopolysaccharidosis, Type I (Hurler Syndrome)?

Mucopolysaccharidosis, Type I is caused by a gene change, or mutation, in both copies of the IDUA gene pair.  These mutations cause the genes to not work properly or not work at all.  The function of the IDUA genes is to create an enzyme which breaks down long chain sugar molecules and clears them from the body.  When both copies of this gene do not work correctly, it causes buildup of certain sugars over time causing cell damage in many organs.  This leads to the symptoms described above.

What is Mucopolysaccharidosis, Type II (Hunter Syndrome)?

Mucopolysaccharidosis, Type II (also called Hunter Syndrome) is an X-linked inherited disorder that affects many parts of the body. It occurs mainly in boys and very rarely affects girls. There are two forms of this disorder, a severe form as well as a mild form. Signs and symptoms of the severe form of Mucopolysaccharidosis, Type II start in early childhood and include intellectual decline and disability, heart disease, and respiratory problems. Signs and symptoms of mild form begin in late childhood or adolescence, progress more slowly, and intelligence is not affected.  Both forms of Mucopolysaccharidosis, Type II have symptoms that often include short stature, large head, large tongue, hearing loss, hoarse voice, spine problems, enlarged liver and spleen, heart problems, and breathing problems. Symptoms worsen over time and people with Mucopolysaccharidosis, Type II have a decreased lifespan with death usually occurring by early adulthood. Treatments are available to help lessen the severity of symptoms. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Mucopolysaccharidosis, Type II (Hunter Syndrome)?

Mucopolysaccharidosis, Type II is caused by a change, or mutation, in the IDS gene.  This mutation causes the gene to not work properly or not work at all.  When the IDS gene in a male does not work correctly, it leads to the symptoms described above. 

What is Mucopolysaccharidosis, Type IIIA (Sanfilippo A)?

Mucopolysaccharidosis, Type IIIA (also called Sanfilippo A) is an autosomal recessive disorder that affects many parts of the body. Signs and symptoms of Mucopolysaccharidosis, Type IIIA usually begin in early childhood and include unusual facial features, a large head size, bone and joint abnormalities, intellectual disability, behavioral problems, sleep difficulties, and coordination and movement problems. Other symptoms include recurrent respiratory and ear infections, vision problems, hearing loss, and hernias. Children lose developmental skills over time, symptoms worsen, and lifespan is shortened with death usually occurring by early adulthood. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Mucopolysaccharidosis, Type IIIA (Sanfilippo A)?

Mucopolysaccharidosis, Type IIIA is caused by a change, or mutation, in both copies of the SGSH gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the SGSH gene do not work correctly, it leads to the symptoms described above.

What is Mucopolysaccharidosis, Type IIIB (Sanfilippo B)?

Mucopolysaccharidosis, Type IIIB (also called Sanfilippo B) is an autosomal recessive disorder that affects many parts of the body.  Signs and symptoms vary from person to person and usually start in childhood, although occasionally do not start until adulthood.  Typical symptoms include unusual facial features, large head size, bone and joint abnormalities, intellectual disability, behavioral problems, sleep difficulties, and coordination and movement problems. Other symptoms may include recurrent respiratory and ear infections, vision problems, hearing loss, and hernias.  Developmental skills are lost over time, symptoms worsen, and lifespan is usually shortened. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Mucopolysaccharidosis, Type IIIB (Sanfilippo B)?

Mucopolysaccharidosis, Type IIIB is caused by a change, or mutation, in both copies of the NAGLU gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of the NAGLU gene do not work correctly, it leads to the symptoms described above.

What is Mucopolysaccharidosis, Type IIIC (Sanfilippo C)?

Mucopolysaccharidosis, Type IIIC (also called Sanfilippo C) is an autosomal recessive disorder that affects many parts of the body. Signs and symptoms of Mucopolysaccharidosis, Type IIIC usually begin in early childhood and include unusual facial features, a large head size, bone and joint abnormalities, intellectual disability, behavioral problems, sleep difficulties, and coordination and movement problems. Other symptoms include recurrent respiratory and ear infections, vision problems, hearing loss, and hernias. Children lose developmental skills over time, symptoms worsen, and lifespan is shortened with death usually occurring by early adulthood. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Mucopolysaccharidosis, Type IIIC (Sanfilippo C)?

Mucopolysaccharidosis Type IIIC is caused by a change, or mutation, in both copies of the HGSNAT gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of the HGSNAT gene do not work correctly, it leads to the symptoms described above. 

What is Mucopolysaccharidosis, Type IIID (Sanfilippo D)?

Mucopolysaccharidosis (MPS), Type IIID (also called Sanfilippo D) is an autosomal recessive disorder that affects many parts of the body. Signs and symptoms vary from person to person and usually start in childhood, although occasionally do not start until adulthood. Typical symptoms include unusual facial features, large head size, bone and joint abnormalities, intellectual disability, behavioral problems, sleep difficulties, and coordination and movement problems. Other symptoms may include recurrent respiratory and ear infections, vision problems, hearing loss, and hernias. Developmental skills are lost over time, symptoms worsen, and lifespan is usually shortened. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Mucopolysaccharidosis, Type IIID (Sanfilippo D)?

MPS, Type IIID is caused by a change, or mutation, in both copies of the GNS gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the GNS gene do not work correctly, it leads to the symptoms described above.

What is Mucopolysaccharidosis, Type IVB/GM1 Gangliosidosis?

Mucopolysaccharidosis (MPS), Type IVB (also called Morquio Syndrome) and GM1 Gangliosidosis are autosomal recessive disorders that affect many parts of the body. Both disorders are caused by mutations in the same gene but they have different signs and symptoms. The more common disorder, GM1 Gangliosidosis, causes progressive loss of nerve cells in the brain and spine. The infantile form of GM1 Gangliosidosis causes weakened muscles, loss of motor skills, developmental delay and intellectual disability, clouding of the cornea of the eye and degeneration of the retina that causes vision loss, and enlargement of the liver, spleen and heart. Babies with this form usually die by early childhood. Some children with GM1 Gangliosidosis do not start showing symptoms until early childhood and do not have organ enlargement but still have loss of skills and a shortened lifespan. In rare cases symptoms do not start until the teenage or early adult years and include episodes of muscle spasms (dystonia), problems with walking and speech, enlarged heart, and memory loss; this adult-onset form is mostly seen in people of Japanese ancestry. The less common disorder, MPS, Type IVB, causes skeletal abnormalities, and abnormal growth of bone and cartilage. Other signs and symptoms of MPS, Type IVB often include short stature, overly mobile joints, hearing loss, breathing problems, spinal cord problems, hernias, sleep apnea, heart disease, multiple cavities in the teeth, and clouding of the cornea of the eye. Intelligence is not affected. Lifespan is decreased in children with the early-onset form of MPS, Type IVB with death often occurring in late childhood or early teens. Lifespan may be near normal in people with the later-onset form. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Mucopolysaccharidosis, Type IVB /GM1 Gangliosidosis?

MPS, Type IVB and GM1 Gangliosidosis are each caused by a change, or mutation, in both copies of the GLB1 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the GLB1 gene do not work correctly, it leads to the symptoms of either GM1 Gangliosidosis or MPS, Type IVB as described above.

What is Mucopolysaccharidosis, Type IX?

Mucopolysaccharidosis, Type IX, also known as Hyaluronidase Deficiency, is a rare autosomal recessive disorder that affects many parts of the body.  Signs and symptoms begin in early childhood and include short stature, episodes of painful soft tissue masses that form around joints, and breakdown of the hip joint that worsens over time. Some children are born with a cleft palate and may have repeated ear infections. Intelligence is not affected. Currently there is no cure for this disorder and treatment is based on symptoms.

What causes Mucopolysaccharidosis, Type IX?

Mucopolysaccharidosis, Type IX is caused by a change, or mutation, in both copies of the HYAL1 gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of the HYAL1 gene do not work correctly, it leads to the symptoms described above.

What is Mucopolysaccharidosis, Type VI (Maroteaux-Lamy)?

Mucopolysaccharidosis, Type VI (also called Maroteaux-Lamy Syndrome) is an autosomal recessive disorder that affects many parts of the body. Signs and symptoms of Mucopolysaccharidosis, Type VI vary from person to person, often begin in early childhood, and include short stature, joint abnormalities, clouding of the cornea of the eye, large head, large tongue, hearing loss, hoarse voice, sleep disturbances, heart valve abnormalities, a buildup of fluid on the brain (hydrocephalus), hernias, and enlarged liver and spleen. Intelligence is not affected.  Symptoms worsen over time and, depending on the severity of the symptoms, lifespan may be shortened. Treatment is available to help minimize the severity of symptoms. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Mucopolysaccharidosis, Type VI (Maroteaux-Lamy)?

Mucopolysaccharidosis, Type VI is caused by a change, or mutation, in both copies of the ARSB gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the ARSB gene do not work correctly, it leads to the symptoms described above.

What is Multiple Sulfatase Deficiency?

Multiple Sulfatase Deficiency (MSD) is a rare autosomal recessive disorder that causes problems in many parts of the body, but mainly in the brain, bones, and skin. Signs and symptoms vary from person to person. The most severe type of MSD, the ‘neonatal form’, has symptoms that begin shortly after birth and include seizures, movement problems, developmental delays, slow growth, excess hair, scaly skin (ichthyosis), scoliosis, other bone problems, and sometimes heart defects and/or enlarged liver and spleen. MRI scans show loss of white matter in the brain (leukodystrophy). Babies with the infantile form often die before the age of one. The most common form of MSD is called ‘late-infantile’ and has symptoms that usually begin by two years of age and include movement problems, progressive developmental delay, ichthyosis, and skeletal changes. Affected children lose developmental skills over time, symptoms worsen, and lifespan is shortened. There is also a rare form of MSD called ‘juvenile-onset’ with similar symptoms that typically begin between the ages of 2 and 4 that progress more slowly than the early-onset forms. Currently, there is no cure or specific treatment for any form of MSD.

What causes Multiple Sulfatase Deficiency?

Multiple Sulfatase Deficiency is caused by a change, or mutation, in both copies of the SUMF1 gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of the SUMF1 gene pair do not work correctly, it leads to the symptoms described above.

What is Muscle-Eye-Brain Disease, POMGNT1-Related?

Muscle-Eye-Brain Disease, POMGNT1-Related is an autosomal recessive condition. It is one of a group of inherited disorders called dystroglycanopathies that affect many parts of the body. Signs and symptoms appear shortly after birth and include muscle weakness (hypotonia), eye abnormalities and vision problems, severe brain abnormalities, water on the brain (hydrocephalus), seizures, developmental delay, intellectual disability, and distinctive facial features. The symptoms and severity vary among affected children. Lifespan is often shortened with death occurring from early childhood to the early teens. There is no cure or specific treatment for this disorder.

Occasionally, mutations in the same gene cause a related form of dystroglycanopathy, either Muscular Dystrophy-Dystroglycanopathy, Type C3 (Limb-Girdle) (MDDGC3) or Muscular Dystrophy-Dystroglycanopathy (Congenital with Mental Retardation) Type B3 (MDDGB3). Even more rarely, a separate condition called Retinitis Pigmentosa 76 may occur that affects only vision.

What causes Muscle-Eye-Brain Disease, POMGNT1-Related?

Muscle-Eye-Brain Disease, POMGNT1-Related is caused by a change, or mutation, in both copies of the POMGNT1 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the POMGNT1 gene do not work correctly, it leads to the symptoms described above.

What is Myoneurogastrointestinal Encephalopathy (MNGIE)?

Myoneurogastrointestinal Encephalopathy (MNGIE) is an autosomal recessive disorder that affects digestion and nerve function.  The main symptom is ‘gastrointestinal dysmotility’, the inability to move food through the digestive tract. This can cause pain, discomfort, nausea, diarrhea, and weight loss. Some people with MNGIE also have tingling, numbness, and weakness in their limbs, especially in their hands and feet.  Weak muscles in or around the eyes, and hearing loss may also occur. Symptoms of MNGIE usually begin before age 20, but can appear in earlier in childhood or late into adulthood.  Currently there is no cure for this disorder and treatment is based on symptoms.

What causes Myoneurogastrointestinal Encephalopathy (MNGIE)?

MNGIE is caused by a gene change, or mutation, in both copies of the TYMP gene pair.  These mutations cause the genes to not work properly or not work at all.  Normal function of the TYMP gene is important in helping the mitochondria (the ‘powerhouses’ in the cells of the body) create energy that the cells can use.  When both copies of the TYMP gene pair do not work correctly, it leads to the symptoms described above.

What is Myotubular Myopathy, X-Linked?

Myotubular Myopathy, X-Linked is an X-linked disorder that occurs mainly in males and causes severe muscle weakness and poor muscle tone starting at birth. Male infants and boys with Myotubular Myopathy, X-Linked have feeding problems, severe breathing problems, and developmental delays. Muscle weakness may also lead to abnormal curvature of the spine, hip and knee contractures, and fragile bones. Some affected boys may also have weak facial muscles, trouble controlling eye movements, absent reflexes, recurrent ear and respiratory infections, or seizures.  Death usually occurs in early childhood.  Currently there is no cure or specific treatment for this condition.

What causes Myotubular Myopathy, X-Linked?

Myotubular Myopathy, X-Linked is caused by a change, or mutation, in the MTM1 gene. This mutation causes the gene to not work properly or not work at all. The MTM1 gene is important for the development and health of the muscles.  When this gene is not working correctly in a male, it causes the symptoms described above. Most female carriers do not have symptoms of Myotubular Myopathy; although rare female carriers are found to have some symptoms, which are generally less severe than those seen in affected males.

What is N-acetylglutamate Synthase Deficiency?

N-acetylglutamate Synthase Deficiency is an autosomal recessive disorder that causes an abnormal buildup of nitrogen, in the form of ammonia, in the blood. Too much ammonia is toxic to the body and causes damage to the brain and nervous system. If the condition is not treated, signs and symptoms often appear early in infancy.  Symptoms include lethargy, feeding and breathing problems, inability to control body temperature, seizures, abnormal movements, and, sometimes, coma.  If left untreated, the condition can lead to developmental delays and intellectual disability.  Some people with this condition have symptoms, often triggered by stress or illness, which do not begin until later in life.  People with the later-onset form have repeated episodes that may include vomiting, confusion, problems with coordination, or coma.  Treatment is needed to prevent or reduce symptoms and includes both a special low protein medical diet and medications to reduce the amount of nitrogen in the body. 

What causes N-acetylglutamate Synthase Deficiency?

N-acetylglutamate Synthase Deficiency is caused by a gene change, or mutation, in both copies of the NAGS gene pair.  These mutations cause the genes to not work properly or not work at all.  The NAGS genes make an enzyme that helps the body get rid of excess nitrogen.  When both copies of the NAGS gene pair do not work correctly, ammonia builds up in the body and leads to the symptoms described above. 

What is Nemaline Myopathy, NEB-Related?

Nemaline Myopathy, NEB-Related is an autosomal recessive disorder that affects skeletal muscles, mainly those in the face, neck, arms, legs, and the muscles that control breathing.  The condition causes both muscle weakness and problems with muscle contraction.  Signs and symptoms are caused by abnormal thread-like rods (“nemaline bodies”) in the muscle cells. Newborns have poor muscle tone (hypotonia) and may have feeding and breathing problems.  Problems with swallowing and speech are also common. Most children with Nemaline Myopathy, NEB-Related are able to walk, although some may begin walking later than usual, and some people eventually need a wheelchair.  Intelligence is not affected. Lifespan is often normal; however, in severe cases, life-threatening breathing problems and lung infections may occur.  Currently there is no cure for this condition and treatment is based on symptoms.

What causes Nemaline Myopathy, NEB-Related?

Nemaline Myopathy, NEB-Related is caused by a gene change, or mutation, in both copies of the NEB gene pair.  These mutations cause the genes to not work properly or not work at all.  Normal function of the NEB genes is important for normal muscle contractions. When both copies of the NEB gene pair do not work correctly, muscles are not able to contract properly, which leads to the symptoms described above. 

What is Neuronal Ceroid Lipofuscinosis, CLN5-Related?

Neuronal Ceroid Lipofuscinosis, CLN5-Related (also known as CLN5 Disease) is autosomal recessive.  It is one of a group of inherited disorders that affect the nervous system as well as other parts of the body. Signs and symptoms of Neuronal Ceroid Lipofuscinosis, CLN5-Related begin in late infancy or early childhood and include coordination and movement problems, epileptic seizures, and vision loss. Over time, children show intellectual decline and lose developmental and motor skills. Wheelchair assistance is usually needed by late childhood.  Symptoms worsen with time and lifespan is shortened with death usually occurring by adolescence.  In rare cases, sy

What causes Neuronal Ceroid Lipofuscinosis, CLN5-Related?

Neuronal Ceroid Lipofuscinosis, CLN5-Related is caused by a change, or mutation, in both copies of the CLN5 gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of the CLN5 gene do not work correctly, it leads to the symptoms described above.

What is Neuronal Ceroid Lipofuscinosis, CLN6-Related?

Neuronal Ceroid Lipofuscinosis, CLN6-Related (also known as CLN6 Disease) is autosomal recessive.  It is one of a group of inherited disorders that affect the nervous system as well as other parts of the body. Signs and symptoms of Neuronal Ceroid Lipofuscinosis, CLN6-Related may first begin in early childhood or not until adulthood. Initial symptoms of the childhood-onset form include epileptic seizures and vision loss. Symptoms of the adulthood-onset form include coordination and movement problems and epileptic seizures without vision loss. Over time, both children and adults with Neuronal Ceroid Lipofuscinosis, CLN6-Related have intellectual decline and lose developmental and motor skills. Symptoms worsen with time and lifespan is shortened. Currently there is no cure or specific treatment for this disorder.

What causes Neuronal Ceroid Lipofuscinosis, CLN6-Related?

Neuronal Ceroid Lipofuscinosis, CLN6-Related is caused by a change, or mutation, in both copies of the CLN6 gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of the CLN6 gene do not work correctly, it leads to the symptoms described above.

What is Neuronal Ceroid Lipofuscinosis, CLN8-Related?

Neuronal Ceroid Lipofuscinosis, CLN8-Related (also known as CLN8 Disease) is autosomal recessive.  It is one of a group of inherited disorders that affect the nervous system as well as other parts of the body. Signs and symptoms of Neuronal Ceroid Lipofuscinosis, CLN8-Related begin in early childhood and include epileptic seizures along with coordination and movement problems. Over time, affected children have vision loss and intellectual decline and lose developmental and motor skills. Symptoms worsen with time and lifespan is often shortened. Some people have a milder form of this condition, sometimes called Northern Epilepsy, which has the same symptoms as described above but with slower progression. People with Northern Epilepsy may live to late adulthood. Currently there is no cure or specific treatment for this disorder.

What causes Neuronal Ceroid Lipofuscinosis, CLN8-Related?

Neuronal Ceroid Lipofuscinosis, CLN8-Related is caused by a change, or mutation, in both copies of the CLN8 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the CLN8 gene do not work correctly, it leads to the symptoms described above.   It is sometime, but not always, possible to tell whether a specific mutation in the CLN8 gene will cause the severe form of Neuronal Ceroid Lipofuscinosis, CLN8-Related or the milder form, Northern Epilepsy. 

What is Neuronal Ceroid Lipofuscinosis, MFSD8-Related?

Neuronal Ceroid Lipofuscinosis, MFSD8-Related (also known as CLN7 Disease) is autosomal recessive.  It is one of a group of inherited disorders that affect the nervous system as well as other parts of the body. Signs and symptoms of Neuronal Ceroid Lipofuscinosis, MFSD8-Related begin in early childhood and include epileptic seizures along with coordination and movement problems.  Over time, affected children have vision loss and intellectual decline and lose developmental and motor skills. Symptoms worsen with time and lifespan is shortened. Currently there is no cure or specific treatment for this disorder.

What causes Neuronal Ceroid Lipofuscinosis, MFSD8-Related?

Neuronal Ceroid Lipofuscinosis, MFSD8-Related is caused by a change, or mutation, in both copies of the MFSD8 gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of the MFSD8 gene do not work correctly, it leads to the symptoms described above.

What is Neuronal Ceroid Lipofuscinosis, PPT1-Related?

Neuronal Ceroid Lipofuscinosis, PPT1-Related (also known as CLN1 Disease) is autosomal recessive.  It is one of a group of inherited disorders that affect the nervous system as well as other parts of the body. Signs and symptoms of Neuronal Ceroid Lipofuscinosis, PPT1-Related often begin in infancy and include coordination and movement problems, epileptic seizures, smaller than average head size (microcephaly), and developmental delay. Over time, affected children have vision loss and intellectual decline and lose developmental and motor skills. Symptoms worsen with time and lifespan is shortened with death usually occurring in childhood.  Some children do not start developing symptoms until early childhood and may survive into their teens. There is also is a less common adult-onset form of Neuronal Ceroid Lipofuscinosis, PPT1-Related, sometimes called Kufs Disease, with symptoms that include seizures, coordination and movement problems, and intellectual decline with shortened lifespan. Currently there is no cure or specific treatment for Neuronal Ceroid Lipofuscinosis, PPT1-Related.   

What causes Neuronal Ceroid Lipofuscinosis, PPT1-Related?

Neuronal Ceroid Lipofuscinosis, PPT1-Related is caused by a change, or mutation, in both copies of the PPT1 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the PPT1 gene do not work correctly, it leads to the symptoms described above.

What is Neuronal Ceroid Lipofuscinosis, TPP1-Related?

Neuronal Ceroid Lipofuscinosis, TPP1-Related (also known as CLN2 Disease, Late-Infantile Neuronal Ceroid Lipofuscinosis, or Juvenile Batten Disease) is autosomal recessive.  It is one of a group of inherited disorders that affect the nervous system as well as other parts of the body. Signs and symptoms of Neuronal Ceroid Lipofuscinosis, TPP1-Related typically begin in early childhood with epileptic seizures. Over time, affected children have vision loss and intellectual decline, develop a movement disorder, and lose developmental and motor skills. Symptoms worsen with time and lifespan is shortened with death usually occurring by adolescence or early adulthood.  Currently there is no cure or specific treatment for this disorder. Very rarely, mutations in the same gene cause a different inherited disorder called Spinocerebellar Ataxia, Type 7 (SCA7).

What causes Neuronal Ceroid Lipofuscinosis, TPP1-Related?

Neuronal Ceroid Lipofuscinosis, TPP1-Related is caused by a change, or mutation, in both copies of the TPP1 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the TPP1 gene do not work correctly, it leads to the symptoms described above.

What is Niemann-Pick Disease, Type C1/D?

Niemann-Pick Disease, Type C1/D is one of a group of autosomal recessive disorders that affect many parts of the body. Signs and symptoms of Niemann-Pick Disease, Type C1/D often begin in childhood and include problems with coordination and muscle movements, seizures, liver and lung disease, abnormal eye movements (supranuclear palsy), and poor muscle tone. Other symptoms may include intellectual disability, seizures, and problems with speech and swallowing that worsen over time. Lifespan is shortened with death often occurring by early adulthood.  In rare cases, symptoms do not occur until adulthood and may also include dementia and behavior changes.  Currently there is no cure or specific treatment for this disorder.

What causes Niemann-Pick Disease, Type C1/D?

Niemann-Pick Disease, Type C1/D is caused by a change, or mutation, in both copies of the NPC1 gene pair.  These mutations cause the genes to not work properly or not work at all.  Normal function of the NPC1 gene pair is needed for normal transport of substances within the cells of the body. When both copies of the NPC1 gene do not work correctly, it leads to the symptoms described above.

What is Niemann-Pick Disease, Type C2?

Niemann-Pick Disease, Type C2 is one of a group of autosomal recessive disorders that affect many parts of the body. Signs and symptoms of Niemann-Pick Disease, Type C2 begin in childhood and include problems with coordination and muscle movements, seizures, liver and lung disease, abnormal eye movements (supranuclear palsy), and poor muscle tone. Other symptoms may include intellectual disability and problems with speech and swallowing that worsen over time. Lifespan is shortened with death often occurring by early adulthood. Currently there is no cure or specific treatment for this disorder.

What causes Niemann-Pick Disease, Type C2?

Niemann-Pick Disease, Type C2 is caused by a change, or mutation, in both copies of the NPC2 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the NPC2 gene do not work correctly, it leads to the symptoms described above.

What is Niemann-Pick Disease, Types A/B?

Niemann-Pick Disease, Types A/B (A and B) refers to two related autosomal recessive disorders that affect many parts of the body.  These conditions result in a build-up of specific types of fats in body cells, tissues, and blood that worsens over time.  Symptoms resulting from the buildup of fats include breathing problems, enlarged liver and spleen, and loss of motor skills.  Niemann-Pick Disease usually results in a shortened lifespan.  Children with Niemann-Pick Disease, Type A have progressive loss of cognitive skills and the condition is typically fatal in early childhood.  Children with Niemann-Pick Disease, Type B often survive into adulthood. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Niemann-Pick Disease, Types A/B?

Niemann-Pick Disease, Types A/ B are caused by gene changes, or mutations, in both copies of the SMPD1 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Nijmegen Breakage Syndrome?

Nijmegen Breakage Syndrome is an autosomal recessive disorder that affects many parts of the body. Signs and symptoms of this disorder begin in infancy and include smaller than average head size (microcephaly), an increased risk for cancer of the immune system (non-Hodgkin’s and other types of lymphoma), increased risk for solid tumor cancers, some degree of intellectual disability, short stature, reproductive problems in females, repeated upper respiratory infections, and distinct facial features. Children lose developmental skills over time, symptoms worsen, and lifespan may be shortened. People with Nijmegen Breakage Syndrome are sensitive to the effects of radiation on the body and should minimize exposure if possible. Currently there is no cure for this disorder and treatment is based on symptoms. Individuals who are carriers for Nijmegen Breakage Syndrome do not have Nijmegen Breakage Syndrome themselves.  However, initial studies suggest that carriers may be at increased risk to develop certain types of cancer.  Further studies need to be done to determine the actual risk for cancer in carriers of Nijmegen Breakage Syndrome and which type of cancers are included in the risk.

What causes Nijmegen Breakage Syndrome?

Nijmegen Breakage Syndrome is caused by a change, or mutation, in both copies of the NBN gene pair. These mutations cause the genes to not work properly or not work at all.  Normal function of the NBN gene pair is needed for repair of damaged DNA within the cells of the body. When both copies of the NBN gene do not work correctly, it leads to the symptoms described above.

What is Non-Syndromic Hearing Loss, GJB2-Related?

Non-Syndromic Hearing Loss, GJB2-Related (also called DFNB1) is an autosomal recessive disorder that causes early-onset hearing loss. “Non-syndromic’ means that no other parts of the body are affected, making hearing loss the only symptom of this condition. In Non-Syndromic Hearing Loss, GJB2-Related, hearing loss is typically present at birth (congenital). However, some children have normal hearing at birth and develop hearing loss during childhood. The severity varies from mild to profound sensorineural hearing loss. The treatment for hearing loss includes hearing aids and, in some cases, cochlear implants.  Non-Syndromic Hearing Loss, GJB2-Related does not cause other health problems.

What causes Non-Syndromic Hearing Loss, GJB2-Related?

Non-Syndromic Hearing Loss, GJB2-Related is caused by a gene change, or mutation, in both copies of the GJB2 gene pair (also known as DFNB1).  These mutations cause the genes to not work properly or not work at all.  The function of the GJB2 gene is to make a protein that is important for hearing. When both copies of the GJB2 gene do not work correctly, it leads to Non-Syndromic Hearing Loss, GJB2-Related.

What is Odonto-Onycho-Dermal Dysplasia/Schopf-Schulz-Passarge Syndrome?

Odonto-Onycho-Dermal Dysplasia (OODD) and Schopf-Schulz-Passarge Syndrome (SSPS) are autosomal recessive types of Ectodermal Dysplasias, a group of inherited disorders that affect the skin, sweat glands, teeth, and nails. OODD and SSPS have similar signs and symptoms including dry and thin body and scalp hair, undeveloped and absent teeth, fingernail abnormalities, excessive or absent sweating, hardening of the skin, especially on the palms of the hands or soles of the feet, and sometimes blistering rashes. SSPS may also cause benign eyelid cysts and sometimes other skin tumors. Many of the symptoms start in childhood; however, some may not show up until adulthood. Currently there is no cure for these conditions and treatment is based on symptoms. Carriers may have no symptoms or may have mild features such as dry skin, nail abnormalities, thin hair, and/or one or more misshapen or missing permanent teeth.

What causes Odonto-Onycho-Dermal Dysplasia /Schopf-Schulz-Passarge Syndrome?

OODD and SSPS are caused by a gene change, or mutation, in both copies of the WNT10A gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms of one of these disorders. 

What is Omenn Syndrome, RAG2-Related?

Omenn Syndrome, RAG2-Related, an autosomal recessive condition, is one of a group of inherited disorders called Severe Combined Immunodeficiency (SCID). People with Omenn Syndrome have immune system problems that prevent their body from fighting off infections. Signs and symptoms begin in infancy and include life-threatening infections, failure to grow and gain weight at the expected rate, severe reddened and peeling skin, chronic diarrhea, and enlarged liver and spleen. Infants and children with this condition often die young. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

Rarely, mutations in the same gene pair that cause Omenn Syndrome cause a related type of autosomal recessive SCID, either Combined Cellular and Humoral Immune Defects with Granulomas or a more severe type of SCID called SCID T negative, B negative, NK positive.

What causes Omenn Syndrome, RAG2-Related?

Omenn Syndrome, RAG2-Related is caused by a gene change, or mutation, in both copies of the RAG2 gene pair. These mutations cause the genes to not work properly or not work at all. Normal function of the RAG2 gene pair is important for the health of the immune system. When both copies of the RAG2 gene do not work properly, it leads to the symptoms described above. 

What is Ornithine Aminotransferase Deficiency?

Ornithine Aminotransferase Deficiency, also known as Gyrate Atrophy of the Choroid and Retina, is an autosomal recessive disorder that causes vision loss.  Loss of eyesight is caused by damage to the parts of the eye called the choroid and retina.  Signs and symptoms usually begin in late childhood and include myopia (nearsightedness) and night blindness.  Vision symptoms worsen with age and can include blindness and cataracts by age fifty. Mild muscle weakness can also occur. Occasionally, affected infants will have high levels of ammonia in the blood that can lead to feeding problems, vomiting, seizures, and, if untreated, may lead to coma.  Medical treatment can correct the high ammonia levels and the episodes stop occurring after infancy.  People with this condition usually have normal intelligence but some have mild to moderate intellectual disability.

What causes Ornithine Aminotransferase Deficiency?

Ornithine Aminotransferase Deficiency is caused by a gene change, or mutation, in both copies of the OAT gene pair. These mutations cause the genes to not work properly or not work at all. Normal function of the OAT genes is important for the health of the eyes and nervous system.  When both copies of the OAT gene do not work correctly, it leads to the symptoms described above. 

What is Ornithine Transcarbamylase Deficiency?

Ornithine Transcarbamylase (OTC) Deficiency is an X-linked inherited disorder that affects males more often than females.  OTC Deficiency causes ammonia to build up in the blood. Ammonia is formed when protein from food is broken down in the body. When ammonia levels become too high, they cause damage to the body. Symptoms of OTC Deficiency most often begin in the first few days after birth. Infants with OTC Deficiency may have low energy (lethargic), be unwilling to eat, have vomiting, and have problems with breathing or body temperature. If untreated, symptoms may worsen to include seizures, muscle weakness, swelling of the brain, coma, or death within the first few weeks of life. Less commonly, symptoms of OTC Deficiency can develop later in infancy, childhood, or adulthood. For those with later onset disease, symptoms can include intellectual disability, enlarged liver or liver disease, dry and brittle hair, avoidance of meat or other high protein foods, and episodes of high ammonia in the blood which can be life threatening if not treated promptly.  Rarely, symptoms do not occur until adulthood and may include migraines, nausea, coordination difficulties, blurred vision, confusion, and hallucinations. When OTC Deficiency is detected early and proper treatment is started immediately, affected children are more likely to be able to live longer lives with improved growth and development. However, even with treatment, some children may still have learning disabilities and/or tight muscles (spasticity).

What causes Ornithine Transcarbamylase Deficiency?

Ornithine Transcarbamylase (OTC) Deficiency is caused by a change, or mutation, in the OTC gene.  This mutation causes the gene to not work properly or not work at all. Males with OTC Deficiency do not make an enzyme that helps with the breakdown of nitrogen in the liver. When nitrogen is not broken down, it builds up in the blood as ammonia and causes the symptoms described above. Some females who are carriers for OTC Deficiency have some symptoms of the disorder, although they are usually milder than those seen in affected males. Female carriers may need special medical care during any pregnancies, as some carriers develop high ammonia levels during pregnancy or after delivery. 

What is Osteopetrosis, Infantile Malignant, TCIRG1-Related?

Osteopetrosis, Infantile Malignant, TCIRG1-Related is a severe autosomal recessive type of Osteopetrosis, a group of disorders that cause bones to become overly dense and fracture easily. Symptoms are usually seen by early infancy and include multiple bone fractures and dense skull bones which often harm nerves in the head and face. The nerve damage may result in loss of vision, hearing, and facial movement. Bones are easily fractured, even with minor falls or stress. Children with Osteopetrosis, Infantile Malignant, TCIRG1-Related may also have reduced bone marrow function which can cause severe anemia and repeated infections. Slow growth, short stature, and enlarged spleen and liver are also common. Some children also have brain abnormalities, seizures and intellectual disability, although this is less common. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Osteopetrosis, Infantile Malignant, TCIRG1-Related?

Osteopetrosis, Infantile Malignant, TCIRG1-Related is caused by a gene change, or mutation, in both copies of the TCIRG1 gene pair. These mutations cause the genes to not work properly or not work at all. The function of the TCIRG1 gene is to help with bone development. When both copies of the TCIRG1 gene pair do not work correctly, it leads to the symptoms described above.

What is Pendred Syndrome?

Pendred Syndrome is an autosomal recessive disorder that causes hearing loss and growths on the thyroid gland called goiters.  Most children with Pendred Syndrome are either born with or develop sudden severe hearing loss by 3 years of age.  Thyroid goiters, which do not usually cause problems with thyroid function, develop in late childhood or early adulthood.  Other symptoms may include difficulties with balance or other inner ear abnormalities.  Some children have a slightly different form of this disorder, sometimes called DFNB4, which includes hearing loss, balance problems, and inner ear abnormalities, but no thyroid goiters. 

What causes Pendred Syndrome?

Pendred Syndrome is caused by a gene change, or mutation, in both copies of the SLC26A4 gene pair. These mutations cause the genes to not work properly or not work at all.  When both copies of the SLC26A4 gene do not work properly, it leads to the symptoms described above. 

What is Phenylketonuria?

Phenylketonuria (PKU) is an autosomal recessive disorder in which the body is unable to breakdown a building block of protein called phenylalanine. When toxic levels of phenylalanine buildup in the body it causes problems for the brain, nervous system, and other parts of the body.  If the condition is not treated, children with Phenylketonuria have intellectual disability, developmental delay, seizures, skin problems, and psychiatric problems.  Lifelong dietary treatment with a diet low in phenylalanine is needed to treat Phenylketonuria.  With treatment people with Phenylketonuria can lead healthy lives.  Other forms of Phenylketonuria called variant PKU and non-PKU hyperphenylalaninemia can be less severe, and have a lower risk for brain and health problems. Some people with very mild cases may not need treatment with a low phenylalanine diet.

What causes Phenylketonuria?

Phenylketonuria is caused by a gene change, or mutation, in both copies of the PAH gene pair. These mutations cause the genes to not work properly or not work at all. Normal function of the PAH genes is important for breaking down phenylalanine from the diet. When both copies of the PAH gene do not work correctly, it leads to the symptoms described above. 

What is Pituitary Hormone Deficiency, Combined 3?

Pituitary Hormone Deficiency, Combined 3 (CPHD3) is an autosomal recessive disorder that causes growth problems, short stature, spine and neck stiffness, sensorineural hearing loss, and other health problems due to lack of pituitary hormones in the body.  Pituitary hormones are made in the brain by the pituitary gland.  Affected infants have low blood sugar (hypoglycemia), seizures, underactive thyroid, and growth delays.  If the condition is not treated, it causes short stature and may cause delayed or absent puberty and infertility (inability to have biological children), and intellectual disability.  Treatment includes lifelong pituitary hormone replacement therapy.

What causes Pituitary Hormone Deficiency Combined-3?

Pituitary Hormone Deficiency Combined-3 (CPHD3) is caused by a change, or mutation, in both copies of the LHX3 gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, the body cannot make the needed pituitary hormones, leading to the symptoms described above.

What is Polycystic Kidney Disease, Autosomal Recessive?

Polycystic Kidney Disease, Autosomal Recessive (ARPKD) is an autosomal recessive disorder that affects the kidneys and other organs, including the liver.  Affected children are typically born with enlarged kidneys with multiple fluid-filled sacs called cysts.  The kidneys do not work properly causing serious health problems.  The fetal kidney problems begin in pregnancy and often affect fetal lung development.  Lung development is affected by low fluid levels in the pregnancy (oligohydramnios) resulting from the kidney disease. Children born with Polycystic Kidney Disease, Autosomal Recessive often have very serious lung disease that may lead to death.  Liver disease (congenital hepatic fibrosis) happens in about 45% of infants and children with Polycystic Kidney Disease, Autosomal Recessive.  The disorder often leads to death in early infancy; however, some children have less severe symptoms and can survive with medical treatments.  In very rare cases, symptoms do not start until adolescence or early adulthood.

What causes Polycystic Kidney Disease, Autosomal Recessive?

Polycystic Kidney Disease, Autosomal Recessive is caused by a gene change, or mutation, in both copies of the PKHD1 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, the kidneys do not develop properly and liver disease may also occur, leading to the symptoms described above.

What is Pontocerebellar Hypoplasia, RARS2-Related?

Pontocerebellar Hypoplasia, RARS2-Related is an autosomal recessive disorder that causes abnormal brain development. The two parts of the brain that are underdeveloped in children with this condition are called the pons and the cerebellum. These parts of the brain help send signals through the brain and also coordinate movement of the body.  The underdeveloped pons and cerebellum cause a child to have a smaller head size (microcephaly), intellectual disability, decreased muscle tone, and vision loss.  This condition usually results in death in infancy or early childhood.  However there have been a few people with Pontocerebellar Hypoplasia, RARS2-Related who have lived into adulthood.

What causes Pontocerebellar Hypoplasia, RARS2-Related?

Pontocerebellar Hypoplasia, RARS2-Related is caused by a gene change, or mutation, in both copies of the RARS2 gene pair. These mutations cause the genes to not work properly or not work at all. Normal function of the RARS2 genes is important for development of the brain. When both copies of the RARS2 gene do not work correctly, it leads to the symptoms described above. 

What is Pontocerebellar Hypoplasia, Type 1A?

Pontocerebellar Hypoplasia, Type 1A is an autosomal recessive disorder that causes abnormalities in the parts of the brain called the pons and cerebellum, leading to problems with muscle movement.  Signs and symptoms are usually present at birth and include a small head size, severe muscle weakness (hypotonia), feeding and breathing problems, joint problems called contractures, intellectual disability, and vision problems.  Lifespan is shortened and death often occurs in infancy or early childhood. There is no cure or specific treatment for this disorder.

Very rarely, specific mutations in the same genes cause a related condition called Hereditary Motor and Sensory Neuropathy, VRK1-Related.  Hereditary Motor and Sensory Neuropathy, VRK1-Related affects the peripheral and sensory nerves leading to weak muscle tone and reduced sense of touch, pain, and temperature.  Children with Hereditary Motor and Sensory Neuropathy, VRK1-Related also have delayed development and a small head size.  Intelligence is normal. 

What causes Pontocerebellar Hypoplasia, Type 1A?

Pontocerebellar Hypoplasia, Type 1A is caused by a gene change, or mutation, in both copies of the VRK1 gene pair.  These mutations cause the genes to not work properly or not work at all. Normal function of the VRK1 genes is important for the development of the brain. When both copies of the VRK1 gene pair do not work correctly, it leads to the symptoms described above. It is sometimes, but not always, possible to determine whether a specific mutation in the VRK1 gene will cause Pontocerebellar Hypoplasia, Type 1A or Hereditary Motor and Sensory Neuropathy, VRK1-Related. 

What is Pontocerebellar Hypoplasia, Type 2D?

Pontocerebellar Hypoplasia, Type 2D (also called Progressive Cerebellocerebral Atrophy) is an autosomal recessive disorder that affects brain development. The two parts of the brain that are underdeveloped in this condition are the pons and the cerebellum. These parts of the brain help send signals through the brain and also coordinate movement of the body. Signs and symptoms of this disorder begin in infancy and include small head size (microcephaly), severe intellectual disability, delayed develop, poor muscle tone with stiff muscles, seizures, vision impairment, and abnormal movement. Death may occur in childhood; however survival into adulthood is possible. Currently there is no cure or specific treatment for this disorder.

What causes Pontocerebellar Hypoplasia, Type 2D?

Pontocerebellar Hypoplasia, Type 2D is caused by a gene change, or mutation, in both copies of the SEPSECS gene pair. These mutations cause the genes to not work properly or not work at all. Normal function of the SEPSECS gene pair is important for the development of the brain. When both copies of the SEPSECS gene do not work correctly, it leads to the symptoms described above. 

What is Primary Ciliary Dyskinesia, DNAH5-Related?

Primary Ciliary Dyskinesia, DNAH5-Related is an autosomal recessive disorder that causes recurrent, chronic respiratory tract infections, abnormal placement of the organs, and infertility.  Some affected newborns require oxygen following delivery due to respiratory distress.  However, the progression and severity of lung disease throughout life varies.  Chronic or recurrent ear infections may occur in infancy or young childhood and can result in hearing loss.  People with this condition may have abnormal organ placement, called ‘situs inversus totalis’ (mirror-image reversal of the organs in the chest and abdomen; for example, the heart is on the right instead of the left).  Affected males have infertility. 

What causes Primary Ciliary Dyskinesia, DNAH5-Related?

Primary Ciliary Dyskinesia, DNAH5-Related is caused by a gene change, or mutation, in both copies of the DNAH5 gene pair. These mutations cause the genes to not work properly or not work at all. Normal function of the DNAH5 genes is important in helping to make cilia (the hair-like structures on cells). Coordinated movement of cilia is necessary for many parts of the body to develop and work properly. When both copies of the DNAH5 gene do not work correctly, it leads to the symptoms described above. 

What is Primary Ciliary Dyskinesia, DNAI1-Related?

Primary Ciliary Dyskinesia, DNAI1-Related is an autosomal recessive disorder that causes recurrent, chronic respiratory tract infections, abnormal placement of the organs, and infertility.  Some affected newborns may require oxygen following delivery due to respiratory distress. However, the progression and severity of lung disease throughout life varies.  Chronic or recurrent ear infections may occur in infancy or young childhood and can result in hearing loss.  People with this condition may have abnormal organ placement, called ‘situs inversus totalis’ (mirror-image reversal of the organs in the chest and abdomen; for example, the heart is on the right instead of the left).  Affected males have infertility. 

What causes Primary Ciliary Dyskinesia, DNAI1-Related?

Primary Ciliary Dyskinesia, DNAI1-Related is caused by a gene change, or mutation, in both copies of the DNAI1 gene pair. These mutations cause the genes to not work properly or not work at all. Normal function of the DNAI1 gene pair is important in helping to make cilia (the hair-like structures on cells). Coordinated movement of cilia is necessary for many parts of the body to develop and work properly. When both copies of the DNAI1 gene do not work correctly, it leads to the symptoms described above. 

What is Primary Ciliary Dyskinesia, DNAI2-Related?

Primary Ciliary Dyskinesia, DNAI2-Related is an autosomal recessive disorder that causes recurrent, chronic respiratory tract infections, abnormal placement of the organs, and infertility.  Some affected newborns require oxygen following delivery due to respiratory distress. However, the progression and severity of lung disease throughout life varies.  Recurrent ear infections may occur in infancy or young childhood and can result in hearing loss. People with this condition may have abnormal organ placement, called ‘situs inversus totalis’ (mirror-image reversal of the organs in the chest and abdomen; for example, the heart is on the right instead of the left).  Affected males have infertility. 

What causes Primary Ciliary Dyskinesia, DNAI2-Related?

Primary Ciliary Dyskinesia, DNAI2-Related is caused by a gene change, or mutation, in both copies of the DNAI2 gene pair. These mutations cause the genes to not work properly or not work at all. Normal function of the DNAI2 gene pair is important in helping to making cilia (the hair-like structures on cells). Coordinated movement of cilia is necessary for many parts of the body to develop and work properly. When both copies of the DNAI2 gene do not work correctly, it leads to the symptoms described above. 

What is Primary Hyperoxaluria, Type 1?

Primary Hyperoxaluria, Type 1 is a rare autosomal recessive disorder that causes the buildup of a substance called calcium oxalate, the main substance found in kidney stones.  Too much calcium oxalate in the body can cause kidney stones and may also damage other organs.  Most people with Primary Hyperoxaluria, Type 1 develop recurrent kidney stones beginning in late childhood but some have a more severe form of this condition that starts by 6 months of age and some do not show symptoms until early adulthood. Kidney damage worsens over time and can lead to kidney failure.  By early adulthood, about half of people with Primary Hyperoxaluria, Type 1 have kidney failure, which is treated with dialysis and then kidney transplantation. Treatment to prevent or reduce the formation of kidney stones includes a special medical diet, supplements, and other oral medications.

What causes Primary Hyperoxaluria, Type 1?

Primary Hyperoxaluria, Type 1 is caused by a gene change, or mutation, in both copies of the AGXT gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene pair do not work correctly, it leads to the symptoms described above.

What is Primary Hyperoxaluria, Type 2?

Primary Hyperoxaluria, Type 2 is an autosomal recessive disorder that causes the buildup of a substance called calcium oxalate, the main substance found in kidney stones.  Too much calcium oxalate in the body can cause kidney stones and may also damage other organs.  Most people with Primary Hyperoxaluria, Type 2 develop recurrent kidney stones beginning in childhood; however, the age of onset can vary. Kidney damage worsens over time and can lead to kidney failure, which is treated with dialysis and then kidney transplantation. Treatment to prevent or reduce the formation of kidney stones includes a special medical diet, supplements, and other oral medications.

What causes Primary Hyperoxaluria, Type 2?

Primary Hyperoxaluria, Type 2 is caused by a gene change, or mutation, in both copies of the GRHPR gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Primary Hyperoxaluria, Type 3?

Primary Hyperoxaluria, Type 3 is an autosomal recessive disorder that causes the buildup of a substance called calcium oxalate, the main substance found in kidney stones.  Too much calcium oxalate in the body can lead to kidney stones and sometimes damages other organs.  Some people with Primary Hyperoxaluria, Type 3 develop kidney stones beginning in childhood, some not until adulthood, and some people never show symptoms. Type 3 is less severe than other forms of Primary Hyperoxaluria (Types 1 and 2).  While Primary Hyperoxaluria, Type 3 has not been reported to cause kidney failure, it is a very rare condition and there is little information available about the health of affected adults. Treatment to prevent or reduce the formation of kidney stones includes a special medical diet, supplements, and other oral medications.

What causes Primary Hyperoxaluria, Type 3?

Primary Hyperoxaluria, Type 3 is caused by a gene change, or mutation, in both copies of the HOGA1 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Progressive Familial Intrahepatic Cholestasis, Type 2?

Progressive Familial Intrahepatic Cholestasis, Type 2 is an autosomal recessive disorder that causes liver disease that worsens over time. Symptoms typically begin in infancy and include severe itching, yellowing of skin and whites of eyes (jaundice), failure to gain weight and grow at the normal rate, high blood pressure in the vein that supplies blood to the liver, and enlarged liver and spleen. Liver failure often occurs within the first years of life and is usually treated with liver transplantation. People with Progressive Familial Intrahepatic Cholestasis, Type 2 are also at increased risk for liver cancer.  Some people have a milder form of this condition which is sometimes called Benign Recurrent Intrahepatic Cholestasis, Type 2.  Benign Recurrent Intrahepatic Cholestasis, Type 2 causes episodes of severe itching and jaundice but liver failure is less common.  It is sometimes, but not always, possible to determine whether a specific gene change, or mutation, will cause Progressive Familial Intrahepatic Cholestasis, Type 2 or Benign Recurrent Intrahepatic Cholestasis, Type 2.

What causes Progressive Familial Intrahepatic Cholestasis, Type 2?

Progressive Familial Intrahepatic Cholestasis, Type 2 is caused by mutations in both copies of the ABCB11 gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of the ABCB11 gene do not work correctly, bile salts cannot be released by liver cells and they build up in the liver, leading to the symptoms described above.

What is Propionic Acidemia, PCCA-Related?

Propionic Acidemia, PCCA-Related (also called Propionic Acidemia, alpha subunit or Propionic Acidemia, Type 1) is an autosomal recessive condition that is one of a group of inherited disorders known as Organic Acid Disorders (OAs). People with Propionic Acidemia cannot break down certain components of proteins (amino acids) and fats. This causes organic acids to build up to toxic levels in the blood and body tissues. Symptoms usually appear soon after birth with hypotonia, feeding difficulties, vomiting, and lethargy. If untreated, children with this condition may develop metabolic acidosis leading to seizures, coma, and sometimes death. Long-term effects of Propionic Acidemia, alpha subunit may include developmental delays, learning disabilities or intellectual disability, involuntary movements, rigid muscle tone (spasticity), and heart problems. In rare cases, the symptoms may start later in life and be less severe. The condition can be managed with a medical diet and supplemental therapies; however, even with careful treatment, some children still have episodes of illness and may have life-long intellectual disability and seizures.

What causes Propionic Acidemia, PCCA-Related?

Propionic Acidemia, PCCA-Related is caused by a gene change, or mutation, in both copies of the PCCA gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Propionic Acidemia, PCCB-Related?

Propionic Acidemia, PCCB-Related (also called Propionic Acidemia, beta subunit or Propionic Acidemia, Type 2) is an autosomal recessive condition that is one of a group of inherited disorders known as Organic Acid Disorders (OAs). People with Propionic Acidemia cannot break down certain building blocks of protein (amino acids) and certain fats. When food with protein is eaten, harmful substances build up in the blood and cause damage to the brain along with other serious health problems. Symptoms usually start shortly after birth and may include low muscle tone (hypotonia), poor feeding, vomiting, low energy (lethargy), dehydration, poor growth, breathing problems, low blood sugar (hypoglycemia), and seizures. Without treatment, coma or death may occur. Episodes of the above symptoms are often triggered by eating large amounts of protein, during illness, or after going a long time without food (fasting). Long-term effects of these episodes may include developmental delays, learning disabilities or intellectual disability, involuntary movements, rigid muscle tone (spasticity), and heart problems. In rare cases, the symptoms may start later in infancy and may be less severe. Treatment includes a medical low-protein diet and formula, specific supplements and medications, and avoidance of fasting. If this condition is treated before symptoms start, children with Propionic Acidemia, PCCB-Related may have normal growth and development. However, even with careful treatment, some children have life-long learning problems or intellectual disability, seizures, and involuntary movements.

What causes Propionic Acidemia, PCCB-Related?

Propionic Acidemia, PCCB-Related is caused by a gene change, or mutation, in both copies of the PCCB gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Pycnodysostosis?

Pycnodysostosis is an autosomal recessive disorder that affects the bones.  Signs and symptoms begin at birth and include short stature, fragile bones, repeated bone fractures, abnormal fingernails, curved spine, absent or abnormal collarbone, distinctive facial features, abnormal teeth, and abnormally developed skull and jawbone.  Adults are typically less than five feet tall.  Currently, there is no cure or specific treatment for this disorder; however, growth hormone replacement may help increase height.

What causes Pycnodysostosis?

Pycnodysostosis is caused by a gene change, or mutation, in both copies of the CTSK gene pair. These mutations cause the genes to not work properly or not work at all. Normal function of the CTSK genes is important for bone health. When both copies of the CTSK genes do not work correctly, it leads to the symptoms described above. 

What is Pyruvate Dehydrogenase Deficiency, PDHB-Related?

Pyruvate Dehydrogenase Deficiency, PDHB-Related is a rare autosomal recessive disorder that causes lactic acid to build up in the body. Too much lactic acid in the blood is toxic and lead to problems with movement and brain function as well as episodes of nausea, vomiting, breathing problems, and abnormal heartbeat. Signs and symptoms usually begin sometime between birth and early childhood, vary from person to person, and range from mild to severe. In addition to the above episodes, symptoms may include poor coordination and unsteadiness, poor muscle control, and intellectual disability that worsen over time. Some people with this condition also have physical differences including brain abnormalities, facial changes, small hands and feet, and short lower limbs. In the most severe cases, a baby shows symptoms before or shortly after birth and early death occurs. Currently there is no cure for this condition. Treatment may include daily supplements to attempt to lessen the symptoms. Lifespan is usually shortened, although children who have symptoms that start later often live into adulthood.

What causes Pyruvate Dehydrogenase Deficiency, PDHB-Related?

Pyruvate Dehydrogenase Deficiency, PDHB-Related is caused by a gene change, or mutation, in both copies of the PDHB gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Pyruvate Dehydrogenase Deficiency, X-Linked?

Pyruvate Dehydrogenase Deficiency, X-Linked is a rare X-linked inherited disorder that causes lactic acid to build up in the body.  This causes problems with movement and brain function. Symptoms vary from person to person and range from mild to severe.  Some people with Pyruvate Dehydrogenase Deficiency, X-Linked have poor coordination and unsteadiness while others have both poor muscle control and intellectual disability that progresses over time.  In the most severe cases of Pyruvate Dehydrogenase Deficiency, X-Linked, a baby shows symptoms before or shortly after birth and early death occurs. Some people with Pyruvate Dehydrogenase Deficiency, X-Linked also have physical differences including facial changes, small hands and feet, and short lower limbs. Males with Pyruvate Dehydrogenase Deficiency, X-Linked are more likely to be severely affected and show symptoms as newborns. Females with this disorder typically have milder symptoms that begin after the newborn period. Currently there is no cure for this disorder but treatment with specific supplements may help reduce symptoms in some individuals.

What causes Pyruvate Dehydrogenase Deficiency, X-Linked?

Pyruvate Dehydrogenase Deficiency, X-Linked is caused by a change, or mutation, in the PDHA1 gene.  This mutation causes the gene to not work correctly or not work at all, causing the symptoms described above.

What is Renal Tubular Acidosis and Deafness, ATP6V1B1-Related?

Renal Tubular Acidosis and Deafness, ATP6V1B1-Related is an autosomal recessive disorder that causes kidney problems and hearing loss.  In this condition, the kidneys cannot clear the body of certain waste products, leading to a buildup of acidic substances in the blood.  As a result, the blood becomes too acidic causing a condition known as metabolic acidosis.  Symptoms of metabolic acidosis include dehydration, nausea, and vomiting.  Over time this disorder can lead to growth delay, kidney stones, and weakened bones (rickets).  Hearing loss usually occurs sometime in childhood or early adulthood and worsens over time.  Treatment to reduce the amount of acid in the blood can help lessen some of the symptoms but currently there is no cure for this disorder.

What causes Renal Tubular Acidosis and Deafness, ATP6V1B1-Related?

Renal Tubular Acidosis and Deafness, ATP6V1B1-Related is caused by a gene change, or mutation, in both copies of the ATP6V1B1 gene pair. These mutations cause the genes to not work properly or not work at all. The ATP6V1B1 gene is important for the normal function of the kidneys and inner ear. When both copies of the ATP6V1B1 gene do not work correctly, it leads to the symptoms described above. 

What is Retinitis Pigmentosa 25?

Retinitis Pigmentosa 25 is autosomal recessive.  It is one of a group of inherited eye disorders in which the retina, the area at the back of the eye that allows you to see, gradually stops working.  Retinitis Pigmentosa 25 causes progressive vision loss.  The age at which symptoms begin and the severity of the condition varies from person to person.  The first symptom is usually loss of night vision. Over time, loss of peripheral vision (tunnel vision) develops.  Then, loss of central vision occurs.  RP affects only the vision.  Currently there is no cure or specific treatment to prevent the vision loss. 

What causes Retinitis Pigmentosa 25?

Retinitis Pigmentosa can be caused by mutations in one of a number of different genes with different inheritance patterns.  Retinitis Pigmentosa 25 is caused by a gene change, or mutation, in both copies of the EYS gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it results in the progressive vision loss described above.

What is Retinitis Pigmentosa 26?

Retinitis Pigmentosa 26 is autosomal recessive.  It is one of a group of inherited eye disorders in which the retina, the area at the back of the eye that allows you to see, gradually stops working.  Retinitis Pigmentosa 26 causes progressive vision loss.  The age at which symptoms begin and the severity of the condition varies from person to person. The first symptom is usually loss of night vision.  Over time, loss of peripheral vision (tunnel vision) develops. Then, loss of central vision occurs.  Retinitis Pigmentosa 26 affects only the vision. Currently there is no cure or specific treatment to prevent the vision loss. 

What causes Retinitis Pigmentosa 26?

Retinitis Pigmentosa can be caused by mutations in one of a number of different genes with different inheritance patterns. Retinitis Pigmentosa 26 is caused by a gene change, or mutation, in both copies of the CERKL gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it results in the progressive vision loss described above.

What is Retinitis Pigmentosa 28?

Retinitis Pigmentosa 28 is autosomal recessive.  It is one of a group of inherited eye disorders in which the retina, the area at the back of the eye that allows you to see, gradually stops working.  Retinitis Pigmentosa 28 causes progressive vision loss.  The age at which symptoms begin and the severity of the condition varies from person to person. The first symptom is usually loss of night vision.  Over time, loss of peripheral vision (tunnel vision) develops. Then, loss of central vision occurs.  Retinitis Pigmentosa 28 affects only the vision.  Currently there is no cure or specific treatment to prevent the vision loss. 

What causes Retinitis Pigmentosa 28?

Retinitis Pigmentosa can be caused by mutations in one of a number of different genes with different inheritance patterns.  Retinitis Pigmentosa 28 is caused by a gene change, or mutation, in both copies of the FAM161A gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it results in the progressive vision loss described above.

What is Retinitis Pigmentosa 59?

Retinitis Pigmentosa 59 is autosomal recessive.  It is one of a group of inherited eye disorders in which the retina, the area at the back of the eye that allows you to see, gradually stops working.  Retinitis Pigmentosa 59 causes progressive vision loss.  The age at which symptoms begin and the severity of the condition varies from person to person. The first symptom is usually loss of night vision.  Over time, loss of peripheral vision (tunnel vision) develops. Then, loss of central vision occurs.  Retinitis Pigmentosa 59 affects only the vision.  Currently there is no cure or specific treatment to prevent the vision loss. 

What causes Retinitis Pigmentosa 59?

Retinitis Pigmentosa can be caused by mutations in one of a number of different genes with different inheritance patterns. Retinitis Pigmentosa 59 is caused by a gene change, or mutation, in both copies of the DHDDS gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it results in the progressive vision loss described above.

What is Rhizomelic Chondrodysplasia Punctata, Type 1?

Rhizomelic Chondrodysplasia Punctata, Type 1 is an autosomal recessive disorder that causes severe problems with bone growth (dwarfism) which are present at birth. Other symptoms include distinct facial features, severe intellectual disability, developmental delay, and breathing problems. Many children born with this disorder die before age two.

Rarely, specific mutations in the same gene cause a different inherited condition called Refsum Disease 2. Signs and symptoms of Refsum Disease 2 include absence of smell and retinitis pigmentosa (gradual vision loss due to buildup of pigment in the retina). Some people with Refsum Disease 2 also have abnormalities of the bones in the hands and feet, muscle weakness, coordination and balance problems, hearing loss, ichthyosis (scaly dry skin), and heart problems. Intelligence is not affected.

What causes Rhizomelic Chondrodysplasia Punctata, Type 1?

Rhizomelic Chondrodysplasia Punctata, Type 1 is caused by a gene change, or mutation, in both copies of the PEX7 gene pair. These mutations cause the genes to not work properly or not work at all. The PEX7 genes help break down different substances stored in the parts of our cells called peroxisomes. When both copies of this gene pair do not work correctly, it causes the buildup of harmful substances in the cells of the body, which leads to the symptoms described above.

What is Rhizomelic Chondrodysplasia Punctata, Type 3?

Rhizomelic Chondrodysplasia Punctata, Type 3 (also called Akyl-DHAP Synthase Deficiency) is an autosomal recessive disorder that causes abnormal bone growth which is present at birth. Children with this condition have a type of short stature called dwarfism where the upper arms and legs are short but the trunk is not. Other signs and symptoms of this condition include distinct facial features, joint pain and stiffness, developmental delays, severe intellectual disability, cataracts, and life-threatening breathing problems. There is no cure for this condition and death often occurs before the age of 10.

What causes Rhizomelic Dysplasia Punctata, Type 3?

Rhizomelic Chondrodysplasia Punctata, Type 3 is caused by a gene change, or mutation, in both copies of the AGPS gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Roberts Syndrome?

Roberts Syndrome is an autosomal recessive disorder that affects many parts of the body.  Signs and symptoms include poor growth (both before and after birth), mild to severe intellectual disability, abnormal knee and elbow joints, and severe birth defects of the bones of the arms, legs, fingers, and toes where the bones and digits may be either shortened or missing.  Birth defects of the face can include a cleft lip, cleft palate, small chin, and small head (microcephaly).  People with Roberts Syndrome may also have heart, kidney and genital problems. Symptoms vary from person to person and may be mild or severe. Infants with severe symptoms are often either stillborn or die in the newborn period.  People with milder symptoms often live into adulthood. There is no cure or specific treatment for this condition.

What causes Roberts Syndrome?

Roberts Syndrome is caused by a change, or mutation, in both copies of the ESCO2 gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Salla Disease?

Salla Disease, one form of Sialic Acid Storage Disease, is an autosomal recessive disorder that mainly affects the nervous system. Most infants with Salla Disease appear normal at birth. Then during infancy signs and symptoms begin to appear including slowly progressing loss of skills, poor muscle tone (hypotonia) that changes with time to tight and stiff muscles (spasticity), seizures, developmental delay,  intellectual disability, speech problems, coordination problems (ataxia), and slow involuntary movements (athetosis) of the arms and legs.  Although symptoms vary from person to person, about two-thirds of people with Salla Disease are not able to walk. Most people with Salla Disease live into adulthood. Currently there is no cure for this condition and treatment is based on the symptoms.

What causes Salla Disease?

Salla Disease is caused by a gene change, or mutation, in both copies of the SLC17A5 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Sandhoff Disease?

Sandhoff Disease is an autosomal recessive disorder that affects the brain and nervous system.  Signs and symptoms usually start in the first year of life and include muscle weakness and loss of motor skills (sitting, crawling, and walking).  Over time, progressive brain damage, seizures, vision and hearing loss, intellectual disability, and paralysis occur.  Death usually occurs in early childhood. In rare cases, symptoms do not begin until the late teenage or adult years.  Symptoms of Late-Onset Sandhoff Disease include muscle weakness in the legs and coordination problems, psychiatric illness, and the gradual loss of motor skills that may lead to problems with speech, swallowing, and walking. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Sandhoff Disease?

Sandhoff Disease is caused by a gene change, or mutation, in both copies of the HEXB gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Schimke Immunoosseous Dysplasia?

Schimke Immunoosseous Dysplasia is an autosomal recessive disorder that causes abnormalities of the bones and a type of short stature called dwarfism.  Signs and symptoms vary from mild to severe and may be present at birth or not until later in childhood.  Typical symptoms include flat spine bones (vertebrae) that cause a short trunk and neck, growth delays, kidney disease that worsens to kidney failure, and a weakened immune system leading to repeated infections that can be life-threatening.  Infants who show early symptoms often die in early childhood. Children who show later onset typically have milder symptoms can live into adulthood.  Adult height usually ranges from three to five feet.  Other symptoms may include heart and lung disease, stroke, excessive curvature of the spine, small or unusually shaped teeth, and darkened patches of skin on the back and neck.  Currently there is no cure for this condition and lifelong medical care is needed. Treatment is based on the symptoms and may include medications to prevent or treat infections and dialysis or a kidney transplant for kidney failure. 

What causes Schimke Immunoosseous Dysplasia?

Schimke Immunoosseous Dysplasia is caused by a gene change, or mutation, in both copies of the SMARCAL1 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above. 

What is Segawa Syndrome, TH-Related?

Segawa Syndrome, TH-Related (one form of Tyrosine Hydroxylase [TH] Deficiency) is an autosomal recessive disorder that affects the brain and nervous system. Signs and symptoms usually begin in infancy or early childhood and include coordination problems, tremor, developmental delays, stiff muscles, abnormal body positioning, drooping eyelids (ptosis), and involuntary jerking movements. Other health problems include constipation, gastroesophageal reflux, and problems maintaining normal blood sugar, body temperature, and blood pressure. Some children have more a more severe form of the disorder with intellectual disability and psychiatric disorders. Currently, there is no cure for this condition, although, for some people, treatment with L-Dopa may help reduce the symptoms. Rarely, specific mutations in the same gene cause less severe form of Tyrosine Hydroxylase Deficiency, TH-Related called Dopa-Responsive Dystonia. Signs and symptoms range from mild to moderate and usually start in childhood with involuntary spasms of the legs, later progressing to the arms and then the rest of the body. Abnormal movements, coordination problems, and sleep disturbance are common. Intellect is not affected. Over time, if Dopa-Responsive Dystonia is not treated, tremor and abnormal repetitive movements similar to those seen in Parkinson disease occur. Treatment with L-Dopa is effective in preventing or reversing the symptoms.

What causes Segawa Syndrome, TH-Related?

Segawa Syndrome, TH-Related is caused by a gene change, or mutation, in both copies of the TH gene pair. These mutations cause the genes to not work properly or not work at all. The TH genes are important for the normal function of the nervous system. When both copies of the TH gene pair do not work properly, it leads to the symptoms described above. 

What is Severe Combined Immunodeficiency, ADA-Related?

Severe Combined Immunodeficiency (SCID) refers to a group of inherited disorders of the immune system. Severe Combined Immunodeficiency, ADA-Related (also called Adenosine Deaminase Deficiency) is an autosomal recessive form of SCID in which the body cannot fight infections caused by bacteria, viruses, and fungi. Signs and symptoms of Severe Combined Immunodeficiency, ADA-Related usually start between six months and one year of age and include repeated long-lasting infections that can be life-threatening, poor growth, diarrhea, and itchy skin rashes. Occasionally, children with this condition have abnormalities of the ribs, liver, and nervous system and may have hearing loss. Without treatment, most children die before the age of two. Some children do not show symptoms until after one year of age and have fewer infections that are less severe. Treatment includes medications to treat the infections and increase immune system function. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Severe Combined Immunodeficiency, ADA-Related?

Severe Combined Immunodeficiency, ADA-Related is caused by a change, or mutation, in both copies of the ADA gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Severe Combined Immunodeficiency, Type Athabaskan?

Severe Combined Immunodeficiency (SCID) refers to a group of inherited disorders of the immune system. Severe Combined Immunodeficiency, Type Athabaskan is an autosomal recessive form of SCID that occurs more often in the Athabaskan-speaking Native American population.  Signs and symptoms of Severe Combined Immunodeficiency, Type Athabaskan usually start between three and six months of age and include chronic infections and sensitivity to ionizing radiation (the type found in X-rays).  Children with Severe Combined Immunodeficiency, Type Athabaskan have immune systems that cannot fight off infections.  They typically have repeated infections that are hard to treat and can be life-threatening.  Infants with this condition may have chronic diarrhea, skin rashes, and slow growth. Without treatment, the condition can be fatal. Treatment includes medications to treat the infections and increase immune system function. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

Rarely, mutations in the same pair of genes that cause Severe Combined Immunodeficiency, Type Athabaskan instead cause a related type of SCID called Omenn Syndrome.  Symptoms of Omenn Syndrome are similar to Severe Combined Immunodeficiency, Type Athabaskan, but also include severe reddened and peeling skin and enlarged liver and spleen. 

What causes Severe Combined Immunodeficiency, Type Athabaskan?

Severe Combined Immunodeficiency, Type Athabaskan is caused by a change, or mutation, in both copies of the DCLRE1C gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Severe Combined Immunodeficiency, X-Linked (XSCID)?

Severe Combined Immunodeficiency, X-Linked (XSCID) is an X-linked inherited disorder of the immune system that affects males more often than females. Signs and symptoms in affected males begin in infancy.  Frequent bacterial, viral or fungal infections that do not respond well to treatment are common. These infections can cause life-threatening problems. Boys with XSCID also have failure to grow at the normal rate, absent tonsils and lymph nodes, gastrointestinal malabsorption (failure of the GI tract to absorb certain nutrients from food) and short stature. Treatment typically includes medications to treat infection and increase immune system function. In many cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Severe Combined Immunodeficiency, X-Linked (XSCID)?

Severe Combined Immunodeficiency, X-Linked (XSCID) is caused by a change, or mutation, in the IL2RG gene. This mutation causes the gene to not work properly or not work at all. When this gene does not work correctly in a male, it leads to the symptoms described above.

What is Sjögren-Larsson Syndrome?

Sjögren-Larsson Syndrome is an autosomal recessive disorder that causes dry, rough, scaly, itchy skin (ichthyosis) along with brain, nerve, and eye problems.  The severity and type of symptoms vary from person to person.  Most children with this condition are born with the skin problems, have delays in motor skills such as crawling and walking because of abnormal stiffness in the legs and arms (spasticity), have some degree of intellectual disability ranging from mild to severe, and often have speech delays with problems forming words.  Many people with Sjögren-Larsson Syndrome need help in walking and some need the use of a wheelchair. Some affected individuals also have seizures, nearsightedness, and increased sensitivity to light (photophobia).  Currently there is no cure for this condition and treatment is based on the symptoms. 

What causes Sjögren-Larsson Syndrome?

Sjögren-Larsson Syndrome is caused by a gene change, or mutation, in both copies of the ALDH3A2 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Smith-Lemli-Opitz Syndrome?

Smith-Lemli-Opitz Syndrome is an autosomal recessive disorder that causes slow growth, small head size, moderate-to-severe intellectual disability, heart defects, cleft palate (opening at the roof of the mouth) and other birth defects. Lifespan in children with Smith-Lemli-Opitz Syndrome is shortened and death occurs before age 2 in up to a third of affected children.  Currently there is no cure for this condition and treatment is based on symptoms.

What causes Smith-Lemli-Opitz Syndrome?

Smith-Lemli-Opitz Syndrome is caused by a gene change, or mutation, in both copies of the DHCR7 gene pair.  These mutations cause the genes to not work properly or not work at all. The function of the DHCR7 genes is to help produce cholesterol.  When there are mutations in both copies of the DHCR7 gene, body cells do not make enough cholesterol and toxic chemicals build up in the blood, nervous system, and other tissues and cause the symptoms described above. Increasing dietary cholesterol cannot cure Smith-Lemli-Opitz Syndrome and has not been proven to be helpful in improving symptoms. 

What is Spinal Muscular Atrophy?            

Spinal Muscular Atrophy, also called SMA, is a serious autosomal recessive disorder that typically begins in infancy or childhood and causes worsening muscle weakness, decreased ability to breathe, and loss of motor skills. Most children with Spinal Muscular Atrophy have one of the early-onset forms with symptoms that begin in infancy, with death often occurring before the age of two. Some children have juvenile-onset SMA and develop muscle weakness and other symptoms later in childhood. In rare cases, symptoms do not begin until early adulthood, are less severe, and do not affect lifespan.  Currently there is no cure for Spinal Muscular Atrophy, although treatments are available that may lessen some of the symptoms in some patients.

What causes Spinal Muscular Atrophy?

Spinal Muscular Atrophy is caused by a change, or mutation, in both copies of the SMN1 gene pair.  These mutations, which often delete part or all of these genes, cause the genes to work improperly or not work at all.  When both copies of the SMN1 gene are missing or do not work correctly, it leads to the symptoms described above. 

What is Spondylothoracic Dysostosis, MESP2-Related?

Spondylothoracic Dysostosis, MESP2-Related (also known as Jarcho-Levin Syndrome) is an autosomal recessive disorder that causes abnormal growth of the spine and rib bones. Infants with Spondylothoracic Dysostosis, MESP2-Related are often born with a small chest and small fused ribs that do not expand well, which can lead to life-threatening breathing problems. Other signs and symptoms include a short stiff neck, abnormally formed vertebrae causing a shortened spine and trunk, scoliosis, and inguinal and umbilical hernias. Intelligence is not affected. Some babies are born with a similar but rare form of this disorder called Spondylocostal Dysostosis, MESP2-Related, which has the same bone abnormalities and other symptoms but the breathing problems are less severe and lower risk of death in infancy. There is no cure for either form of this disorder although careful medical treatment is important for infants with breathing problems and surgery may be needed for spine problems or hernias.

What causes Spondylothoracic Dysostosis, MESP2-Related?

Spondylothoracic Dysostosis, MESP2-Related is caused by a gene change, or mutation, in both copies of the MESP2 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Steroid-Resistant Nephrotic Syndrome?

Steroid-Resistant Nephrotic Syndrome is an autosomal recessive disorder that causes abnormal kidney function.  People with this condition have large amounts of protein in their urine, low amounts of albumin (a protein in the plasma of the blood), high levels of fat in the blood, and excess fluid in body tissues (edema).  Symptoms vary from person to person but usually start in childhood.  The kidney problems worsen over time, often leading to kidney failure in the teenage years or early adulthood.   Once kidney failure occurs, dialysis and then kidney transplantation are needed.  Currently there is no cure for this condition and treatment is based on symptoms.

What causes Steroid-Resistant Nephrotic Syndrome?

Steroid-Resistant Nephrotic Syndrome is caused by a gene change, or mutation, in both copies of the NPHS2 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Stuve-Wiedemann Syndrome?

Stuve-Wiedemann Syndrome is a rare autosomal recessive disorder that causes severe bone abnormalities.  Signs and symptoms are present at birth and include short stature, bowing of the long bones of the arms and legs (campomelia), and flexed fingers and toes (camptodactyly).  Babies with this condition have repeated episodes of severe fever (hyperthermia) and breathing problems that can be life-threatening. Infants with Stuve-Wiedemann Syndrome rarely survive. In those that do, scoliosis, bone fractures, joint abnormalities, bowing of limbs, and poor muscle tone (hypotonia) are common. Sleep apnea and feeding and swallowing problems can also occur. Currently there is no cure for this condition and treatment is based on the symptoms.

What causes Stuve-Wiedemann Syndrome?

Stuve-Wiedemann Syndrome is caused by a change, or mutation, in both copies of the LIFR gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly it leads to the symptoms described above.

What is Tay-Sachs Disease?

Tay-Sachs Disease is an autosomal recessive disorder that affects the brain and nervous system with signs and symptoms usually starting in the first year of life.  Symptoms include muscle weakness, loss of motor skills such as turning over, sitting, and crawling. Over time, progressive brain damage, seizures, vision and hearing loss, intellectual disability, and paralysis occur. Death usually occurs in early childhood.  In rare cases, symptoms do not begin until early adulthood and progress slowly. In some cases, affected individuals have been treated with stem cell transplantation from cord blood or bone marrow. Couples at risk of having an affected child may consider cord blood banking, as siblings have a higher chance of being a match for stem cell transplantation than a non-related individual.

What causes Tay-Sachs Disease?

Tay-Sachs Disease is caused by a gene change, or mutation, in both copies of the HEXA gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of the HEXA gene do not work correctly, it leads to the symptoms described above.

What is Tyrosinemia, Type 1?

Tyrosinemia, Type 1 is an autosomal recessive disorder in which the body is unable to break down a building block of protein (amino acid) called tyrosine.  This condition causes a harmful buildup of tyrosine and other amino acids and toxins in the body leading serious health problems.  The signs and symptoms of untreated Tyrosinemia, Type 1 usually begin in infancy and include diarrhea, bloody stool, vomiting, swollen abdomen, poor weight gain, lethargy (tiredness), irritability, yellowing skin (jaundice), cabbage-like odor, bleeding problems, breathing trouble, and developmental delays.  If not treated, Liver and kidney failure as well as nervous system problems can occur. Babies with Tyrosinemia, Type 1 need lifelong dietary and medical treatments.  Early treatment can help prevent the liver, kidney, and brain problems.  Children who receive treatment early in life can often have healthy growth and development.

What causes Tyrosinemia, Type 1?

Tyrosinemia, Type 1 is caused by a gene change, or mutation, in both copies of the FAH gene pair. These mutations cause the genes to not work properly or not work at all. The function of the FAH genes is to breakdown tyrosine. When both copies of this gene do not work correctly, it can cause a buildup of toxic substances in the body which leads to the symptoms described above.

What is Usher Syndrome, Type 1B?

Usher Syndrome, Type 1B is autosomal recessive.  It is one of a group of inherited disorders that cause progressive hearing and vision loss.  In most cases of Usher Syndrome, Type 1B, severe hearing loss is present at birth and hearing aids are not usually helpful.  Balance is also affected, which leads to a delay in motor skills such as walking.  Retinitis Pigmentosa is an eye condition that occurs in most people with Usher Syndrome Type 1B and leads to damage to the retina, causing progressive loss of eyesight and eventual blindness.  Retinitis Pigmentosa with vision loss usually starts developing in childhood.  Usher Syndrome, Type 1B does not affect intelligence or life span.

The symptoms of Usher Syndrome, Type 1B vary from person to person and some people have less severe (moderate) hearing loss. Other people may have hearing loss only and do not develop Retinitis Pigmentosa.  Currently there is no cure for Usher Syndrome, Type 1B.

What causes Usher Syndrome, Type 1B?

Usher Syndrome, Type 1B is caused by a gene change, or mutation, in both copies of the MYO7A gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Usher Syndrome, Type 1C?

Usher Syndrome, Type 1C is autosomal recessive.   It is one of a group of inherited disorders that cause progressive hearing and vision loss.  In most cases of Usher Syndrome, Type 1C, severe hearing loss in both ears is present at birth and hearing aids are not usually helpful.  Balance is also affected, which leads to delays in motor skills such as walking.  Retinitis Pigmentosa is an eye condition that occurs in most people with Usher Syndrome, Type 1C and leads to damage to the retina, causing progressive loss of eyesight.  Retinitis Pigmentosa with vision loss often starts in the teenage years but sometimes not until adulthood.  Usher Syndrome, Type 1C does not affect intelligence or life span.

The symptoms of Usher Syndrome, Type 1C vary from person to person and some affected individuals have less severe (moderate) hearing loss. Others have hearing loss only and do not develop Retinitis Pigmentosa.  Currently there is no cure for Usher Syndrome, Type 1C.

What causes Usher Syndrome, Type 1C?

Usher Syndrome, Type 1C is caused by a gene change, or mutation, in both copies of the USH1C gene pair.  These mutations cause the gene to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Usher Syndrome, Type 1D?

Usher Syndrome, Type 1D is autosomal recessive.  It is one of a group of inherited disorders that cause progressive hearing and vision loss.  In most cases of Usher Syndrome, Type 1D, severe hearing loss is present at birth and hearing aids are not usually helpful.  Balance is also affected, which leads to a delay in motor skills such as walking.  Retinitis Pigmentosa is an eye condition that occurs in people with Usher Syndrome Type 1D and leads to damage to the retina, causing progressive loss of eyesight and eventual blindness.  Retinitis Pigmentosa with vision loss may start developing in childhood or not until adulthood.  Usher Syndrome, Type 1D does not affect intelligence or life span. The symptoms of Usher Syndrome, Type 1D vary from person to person and some affected individuals have less severe (moderate) hearing loss. Others may have hearing loss only and do not develop Retinitis Pigmentosa.  Currently there is no cure for Usher Syndrome, Type 1D.

What causes Usher Syndrome, Type 1D?

Usher Syndrome, Type 1D is caused by a gene change, or mutation, in both copies of the CDH23 gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Usher Syndrome, Type 1F?

Usher Syndrome, Type 1F is autosomal recessive.  It is one of a group of inherited disorders that cause progressive hearing and vision loss.  In most cases of Usher Syndrome, Type 1F, severe hearing loss is present at birth and hearing aids are not usually helpful.  Balance is also affected, which leads to a delay in motor skills such as walking.  Retinitis Pigmentosa is an eye condition that occurs in most people with Usher Syndrome Type 1F and leads to damage to the retina, causing progressive loss of eyesight and eventual blindness.  Retinitis Pigmentosa with vision loss typically starts developing in the teenage years or early adulthood.  Usher Syndrome, Type 1F does not affect intelligence or life span. The symptoms of Usher Syndrome, Type 1F vary from person to person and some people have less severe (moderate) hearing loss. Other people may have hearing loss only and do not develop Retinitis Pigmentosa.  Currently there is no cure for Usher Syndrome, Type 1F.

What causes Usher Syndrome, Type 1F?

Usher Syndrome, Type 1F is caused by a gene change, or mutation, in both copies of the PCDH15 gene pair.  These mutations cause the genes to not work properly or not work at all.  When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Usher Syndrome, Type 2A?

Usher Syndrome, Type 2A is autosomal recessive.  It is one of a group of inherited disorders that cause progressive hearing and vision loss.  In most cases of Usher Syndrome, Type 2A, moderate to severe hearing loss is present at birth and affects higher frequencies more than lower frequencies.  Speech involves lower frequencies, so speech and understanding language is often possible for children with this condition, although hearing aids and speech therapy are often needed.  Retinitis Pigmentosa is an eye condition that occurs in individuals with Usher Syndrome, Type 2A and leads to damage to the retina, causing progressive loss of eyesight.  Retinitis Pigmentosa with vision loss usually starts in the teenage years.  Usher Syndrome, Type 2A does not affect intelligence or life span. Some individuals with Usher Syndrome, Type 2A have Retinitis Pigmentosa only and do not have hearing loss. Currently there is no cure for this condition.

What causes Usher Syndrome, Type 2A?

Usher Syndrome, Type 2A is caused by a gene change, or mutation, in both copies of the USH2A gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Usher Syndrome, Type 3?

Usher Syndrome, Type 3 is autosomal recessive.  It is one of a group of inherited disorders that cause progressive hearing and vision loss.  People with Usher Syndrome, Type 3 usually start losing their hearing in late childhood or the early teenage years and typically have profound deafness by adulthood.  Balance may also be affected, causing problems with walking and coordination. Retinitis Pigmentosa is an eye condition that occurs in most individuals with Usher Syndrome, Type 3 and leads to damage to the retina, causing progressive loss of eyesight starting in childhood or the teenage years.  Usher Syndrome, Type 3 does not affect intelligence or life span.

The symptoms of Usher Syndrome, Type 3 vary from person to person and some people have less severe hearing loss. Other people may have hearing loss only and do not develop Retinitis Pigmentosa.  Currently there is no cure for this Usher Syndrome, Type 3.

What causes Usher Syndrome, Type 3?

Usher Syndrome, Type 3 is caused by a gene change, or mutation, in both copies of the CLRN1 gene pair.  These mutations cause the genes to not work properly or not work at all. When both copies of this gene do not work correctly, it leads to the symptoms described above.

What is Very Long-Chain Acyl-CoA Dehydrogenase Deficiency?

Very Long-Chain Acyl-CoA Dehydrogenase Deficiency (VLCAD Deficiency) is an autosomal recessive disorder that prevents the body from breaking down certain fats to energy, particularly during periods of fasting, illness, or exercise.  Signs and symptoms can begin anytime between infancy and adulthood.  Infants with the most severe form of VLCAD Deficiency develop symptoms in the first few months of life.  VLCAD Deficiency causes a thickening of the heart muscle (cardiomyopathy) which causes the heart not to work properly.  It can also cause an abnormal heart rhythm and/or fluid around the heart.  Infants with VLCAD Deficiency can have poor muscle tone, lack of energy, an enlarged liver, and periods of low blood sugar (hypoglycemia).  If not treated, affected infants can die.  With early diagnosis and lifelong treatment, infants with VLCAD Deficiency can survive and may have healthy growth and development. Affected individuals who develop symptoms in childhood may not have heart disease.  People with the childhood-onset form typically have low blood sugar, an enlarged liver, and muscle weakness, especially after exercise.  Most individuals with VLCAD Deficiency have signs and symptoms that do not begin until adulthood.  This milder form typically does not affect the heart and may or may not cause low blood sugar.  Individuals with VLCAD Deficiency that begins in adulthood can have muscle cramps and pain, often following exercise.  If untreated, the body breaks down muscles and kidney damage can occur.  With careful treatment, people with the childhood and adult forms of VLCAD Deficiency can live healthy lives with typical growth and development.

What causes Very Long-Chain Acyl-CoA Dehydrogenase Deficiency?

VLCAD Deficiency is caused by a gene change, or mutation, in both copies of the ACADVL gene pair.  These mutations cause the genes to not work properly or not work at all.  The function of the ACADVL genes is to help break down fat in the body so that it can be used for energy.  When both copies of this gene do not work correctly, the body cannot break down fats which build up and cause the symptoms described above.

What is Walker-Warburg Syndrome, FKTN-Related?

Walker-Warburg Syndrome, FKTN-Related is an autosomal recessive disorder that affects many parts of the body, especially the brain, eyes, and muscles. Signs and symptoms are often present before birth but sometimes start in infancy and include weak muscle tone (hypotonia), excess fluid on the brain (hydrocephalus), severe brain abnormalities, and eye defects with vision problems. Infants and children with Walker-Warburg Syndrome, FKTN-Related have worsening muscle weakness, problems with movement and coordination, seizures, and severe developmental delay with intellectual disability. Although symptoms vary from person to person, lifespan is usually shortened with death often occurring in early childhood. There is no cure or specific treatment for this disorder. Rarely, mutations in the same pair of genes cause either a related condition called Fukuyama Congenital Muscular Dystrophy, a milder condition called Limb-Girdle Muscular Dystrophy, Type 2M (also known as Type C4), or, very rarely, Dilated Cardiomyopathy, Type 1X. Fukuyama Congenital Muscular Dystrophy causes brain and eye abnormalities and severe muscle weakness and is found mainly in people of Japanese ancestry. Limb-Girdle Muscular Dystrophy, Type 2M causes progressive weakness in the muscles of the arms, legs, shoulders, and hips but does not affect the brain. Symptoms of Dilated Cardiomyopathy, Type 1X include an enlarged and weakened heart and sometimes muscle weakness, usually beginning in adulthood.

What causes Walker-Warburg Syndrome, FKTN-Related?

Walker-Warburg Syndrome, FKTN-Related is caused by a change, or mutation, in both copies of the FKTN gene pair. These mutations cause the genes to not work properly or not work at all. When both copies of the FKTN gene do not work correctly, it leads to the symptoms described above.

What is Wilson Disease?

Wilson Disease is an autosomal recessive disorder that causes copper from the diet to build up in certain parts of the body, especially the liver, eyes, and brain. Signs and symptoms of Wilson Disease usually begin in the teenage years and in rare cases not until adulthood.  Symptoms include liver disease, nervous system and psychiatric problems, and specific eye findings called Kayser-Fleischer rings (green/brown colored areas of excess copper on the surface of the eyes that do not interfere with vision). Other symptoms may include problems with coordination, movement, and behavior. Wilson Disease is commonly treated through chelation therapy to remove the excess stored copper from the body. This treatment helps to slow, and in some cases stop, the progression of the disease and improve symptoms.  With treatment, people with Wilson Disease can have a normal lifespan.

What causes Wilson Disease?

Wilson Disease is caused by a change, or mutation, in both copies of the ATP7B gene pair. These mutations cause the genes to not work properly or not work at all.  Normal function of the ATP7B genes is needed for normal transport of copper within the cells of the body. When both copies of the ATP7B gene do not work correctly, it leads to the symptoms described above.

What is Wolman Disease?

Wolman Disease, a form of Lysosomal Acid Lipase Deficiency, is an autosomal recessive disorder in which the body is unable to break down and use cholesterol and fats from the diet.  Cholesterol and fats then build up in many organs of the body and lead to the disease symptoms. Signs and symptoms usually begin in infancy and include enlarged liver and spleen (hepatosplenomegaly), poor weight gain, poor muscle tone, yellowing of the skin and the whites of the eyes (jaundice), liver disease, anemia, vomiting, and diarrhea.  Infants with Wolman Disease also have developmental delays and are malnourished. Without treatment, most affected children die in infancy or early childhood. A milder form of Lysosomal Acid Lipase Deficiency, called Cholesteryl Ester Storage Disease, has symptoms that vary from person to person and include buildup of cholesterol and fats in the body, enlarged liver with cirrhosis, hardening of the arteries (atherosclerosis), and an increased risk for heart disease and stroke.  Symptoms may start in early childhood or not until adulthood and lifespan may be decreased. Enzyme replacement therapy and other medications are available for both forms of Lysosomal Acid Lipase Deficiency and may be helpful in lessening the symptoms.

What causes Wolman Disease?

Wolman Syndrome is caused by a gene change, or mutation, in both copies of the LIPA gene pair. These mutations cause the genes to not work properly or not work at all. The LIPA gene is important for the breakdown of cholesterol and triglycerides in the body. When both copies of the LIPA gene pair do not work properly, it leads to the symptoms described above. 

What is Zellweger Spectrum Disorders, PEX1-Related?

Zellweger Spectrum Disorders, PEX1-Related refers to a group of autosomal recessive conditions that includes Zellweger Syndrome, the most severe form; Infantile Refsum Disease (IRD) and Neonatal Adrenoleukodystrophy (NALD), intermediate in severity; and Heimler Syndrome, the mildest form.  Children born with Zellweger Spectrum Disorders, PEX1-Related can have signs and symptoms in the newborn period or not until later in childhood.  Signs and symptoms of Zellweger Syndrome, the most severe form, include low muscle tone (hypotonia), feeding problems, distinctive facial features, developmental delay, seizures, and liver disease.  Infants with Zellweger Syndrome often die in the first year of life.  Children with Infantile Refsum Disease or Neonatal Adrenoleukodystrophy often have longer survival with symptoms that include slowly progressing vision and hearing loss, intellectual disability, developmental delay, hypotonia, liver disease, and other medical problems.  Heimler Syndrome is a milder and very rare condition with symptoms that include sensorineural hearing loss, nail abnormalities, and loss of tooth enamel; intelligence is not affected.  Currently there is no cure for these disorders and treatment is based on symptoms.

What causes Zellweger Spectrum Disorders, PEX1-Related?

Zellweger Spectrum Disorders, PEX1-Related are caused by a gene change, or mutation, in both copies of the PEX1 gene pair.  These mutations cause the genes to not work properly or not work at all.  The normal function of the PEX1 gene pair is to help makes structures in our cells called peroxisomes that clear harmful substances from the body. When both copies of the PEX1 gene do not work correctly, peroxisomes do not form correctly in the cells of our body, leading to the symptoms described above.

What is Zellweger Spectrum Disorders, PEX10-Related?

Zellweger Spectrum Disorders, PEX10-Related refers to a group of autosomal recessive disorders that includes Zellweger Syndrome, the most severe form, along with Infantile Refsum Disease (IRD) and Neonatal Adrenoleukodystrophy (NALD) which are intermediate in severity. Children born with Zellweger Spectrum Disorders, PEX10-Related can have signs and symptoms in the newborn period or not until later in childhood.  Signs and symptoms in Zellweger Syndrome, the most severe form, include low muscle tone (hypotonia), feeding problems, distinctive facial features, developmental delay, seizures, and liver disease.  Infants with Zellweger Syndrome often die in the first year of life.  Children with Infantile Refsum Disease or Neonatal Adrenoleukodystrophy often have longer survival with symptoms that include slowly progressing vision and hearing loss, intellectual disability, developmental delay, hypotonia, liver disease, and other medical problems.  Currently there is no cure for these disorders and treatment is based on symptoms.

What causes Zellweger Spectrum Disorders, PEX10-Related?

Zellweger Spectrum Disorders, PEX10-Related are caused by a change, or mutation, in both copies of the PEX10 gene pair.  These mutations cause the genes to not work properly or not work at all.  The normal function of the PEX10 genes is to help make peroxisomes, structures in our cells that clear harmful substances from the body. When both copies of the PEX10 gene do not work correctly, peroxisomes do not form correctly, leading to the symptoms described above.

What is Zellweger Spectrum Disorders, PEX2-Related?

Zellweger Spectrum Disorders, PEX2-Related refers to a group of autosomal recessive disorders that includes Zellweger Syndrome, the most severe, along with Infantile Refsum Disease (IRD) and Neonatal Adrenoleukodystrophy (NALD) which are intermediate in severity. Children born with Zellweger Spectrum Disorders, PEX2-Related can have signs and symptoms in the newborn period or not until later in childhood.  Signs and symptoms in Zellweger Syndrome, the most severe form, include low muscle tone (hypotonia), feeding problems, distinctive facial features, developmental delay, seizures, and liver disease.  Infants with Zellweger Syndrome often die in the first year of life.  Children with Infantile Refsum Disease or Neonatal Adrenoleukodystrophy often have longer survival with symptoms that include slowly progressing vision and hearing loss, intellectual disability, developmental delay, hypotonia, liver disease, and other medical problems.  Currently there is no cure for these disorders and treatment is based on symptoms.

What causes Zellweger Spectrum Disorders, PEX2-Related?

Zellweger Spectrum Disorders, PEX2-Related are caused by a change, or mutation, in both copies of the PEX2 gene pair.  These mutations cause the genes to not work properly or not work at all.  The normal function of the PEX2 genes is to help make peroxisomes, structures in our cells that clear harmful substances from the body. When both copies of the PEX2 gene do not work correctly, peroxisomes do not form correctly, leading to the symptoms described above.

What is Zellweger Spectrum Disorders, PEX6-Related?

Zellweger Spectrum Disorders, PEX6-Related refers to a group of autosomal recessive conditions that includes Zellweger Syndrome, the most severe form; Infantile Refsum Disease (IRD) and Neonatal Adrenoleukodystrophy (NALD), intermediate in severity; and Heimler Syndrome, the mildest form.  Children born with Zellweger Spectrum Disorders, PEX6-Related can develop signs and symptoms in the newborn period or later in childhood.  Signs and symptoms in Zellweger Syndrome, the most severe form, include low muscle tone (hypotonia), feeding problems, distinctive facial features, developmental delay, seizures, and liver disease.  Infants with Zellweger Syndrome often die in the first year of life.  Children with Infantile Refsum Disease or Neonatal Adrenoleukodystrophy often have longer survival with symptoms that include slowly progressing vision and hearing loss, intellectual disability, developmental delay, hypotonia, liver disease, and other medical problems.  Heimler Syndrome is a milder and very rare condition with symptoms that include sensorineural hearing loss, nail abnormalities, and loss of tooth enamel; intelligence is not affected. Currently there is no cure for these disorders and treatment is based on symptoms.

What causes Zellweger Spectrum Disorders, PEX6-Related?

Zellweger Spectrum Disorders, PEX6-Related are caused by a change, or mutation, in both copies of the PEX6 gene pair.  These mutations cause the genes to not work properly or not work at all. The normal function of the PEX6 genes is to help make peroxisomes, structures in our cells that clear harmful substances from the body.  When both copies of the PEX6 gene do not work correctly, peroxisomes do not form correctly, leading to the symptoms described above.