Diseases detected by the GeneScreen test

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.