Familial Dysautonomia (FD), also known as Riley-Day Syndrome is a progressive disease that affects the development of the autonomic and sensory nervous systems. As a result, important body functions such as swallowing, temperature and blood pressure regulation, and sensitivity to pain are impaired. Other symptoms of FD include lack of tears, gastrointestinal dysfunction, vomiting crises, recurrent pneumonia, mild to moderate developmental delay, poor motor coordination, scoliosis, and slurred or labored speech. FD is present at birth and is associated with a reduced life expectancy.
There is no cure for FD. Treatments for FD are aimed at managing the symptoms.
One in 30 Ashkenazi Jewish individuals is a carrier of FD. Because of this high carrier rate, the American College of Medical Genetics (ACMG) and the American College of Obstetrics and Gynecology (ACOG) recommend FD carrier screening for all people with Ashkenazi Jewish ancestry.
How Is Familial Dysautonomia Inherited?
The cells in our body typically contain 46 chromosomes. Each chromosome is a package that holds hundreds of genes. These genes contain the all of the blueprints for our growth and development; they are the instructions that make us who we are. All of our chromosomes (and the genes that are located on these chromosomes) come in pairs. We inherit one chromosome of each pair from our mother and the other chromosome of the pair from our father.
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When there is a change in a gene (called a mutation) the instructions it contains are no longer correct and the gene cannot carry out its function. Individuals with FD have two copies of a mutation, one copy inherited from each parent. Neither gene in the pair is working correctly, which causes the symptoms of the disease.
A carrier of FD is a person who has a mutation in one gene of the pair. Carriers are unaffected with the disease because the properly working gene is able to compensate for the gene that contains the mutation.
When two parents are carriers of FD:
- there is a 1 in 4 (25%) chance of having a child with FD,
- there is a 1 in 2 (50%) chance of having a child who is an unaffected carrier like the parents,
- and, there is 1 in 4 (25%) chance of having a child who is unaffected and is not carrier.
When one parent is a carrier of FD and the other parent is not a carrier, they are not at increased risk to have a child with FD. Instead, there is a 1 in 2 (50%) chance of having a child with is an unaffected carrier like the one parent.
What This Test Tells You
This test will tell you whether you are a carrier of FD. It detects >99.5% of mutations that cause FD in people of Ashkenazi Jewish descent. The mutations are called IVS20 (+6T C) and R696P, and the gene is called IKBKAP.
How Testing Works
Testing with DNA Direct is quick, convenient, and can be done in the privacy of your home. It can also be anonymous if you wish. How to order online and consult with our genetic experts: DNA Direct's Expert Services
References:
1. Anderson SL, Coli R, Daly IW. et al. Familial dysautonomia is caused by mutations of the IKP gene. Am J Hum Genet. 2001; 68(3):753-758.2. Dong J, Edelmann L, Bajwa AM. et al. Familial dysautonomia: Detection of the IKBKAP IVS20(+6T)C and R696P mutations and frequencies among ashkenazi jews. Am J Med Genet. 2002; 110(3):253-257.
3. Slaugenhaupt SA, Blumenfeld A, Gill SP. et al. Tissue-specific expression of a splicing mutation in the IKBKAP gene causes familial dysautonomia. Am J Hum Genet. 2001;68(3):598-605.
4. American college of obstetricians and gynecologists. Prenatal and preconceptional carrier screening for genetic diseases in individuals of eastern european jewish descent. Technical Bulletin 298. Washington, DC: ACOG, August 2004.
