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Jewish genetic disease carrier screeningIn every ethnic, demographic or racial group, there are inherited disorders that occur more frequently than in the general population. Such is the case for Ashkenazi Jews whose ancestors lived in Central or Eastern Europe. If you and/or your spouse are of Ashkenazi Jewish descent, you can be screened for 9 inherited diseases. What is genetic screening?Our genes determine every trait in our bodies like hair color, eye color, blood type, and even being affected with a genetic disease. We inherit 2 genes for each trait, one from our mom and one from our dad. Some genes have a mutation in which they are not working properly. Certain diseases are caused when both genes in a pair have a mutation. This is called a recessive disease. All of the common Ashkenazi Jewish genetic diseases are inherited in a recessive manner. It is possible, however, for an individual to be a carrier for a genetic disorder. A carrier is a healthy individual who has one working and one non-working copy in the gene associated with a disease. Being a carrier for a disease does not cause health problems. Genetic screening can identify carriers by a simple blood test to determine if a couple is at risk to have a child affected with a specific disorder. Common Ashkenazi Jewish genetic diseasesYou may decide to be screened for each of the 9 diseases described below or for selected diseases. Tay-Sachs Disease Tay-Sachs is a disorder in which the central nervous system progressively degenerates. This causes loss of coordination, seizures, difficulty swallowing and poor pulmonary function. Symptoms usually appear at about 6 months of age. Eventually, children with Tay-Sachs become blind, severely mentally retarded, paralyzed and unaware of their surroundings. There is no treatment and average life expectancy is 3-5 years. About 1 in 25 Asheknazi Jews is a Tay-Sachs carrier. The gene is also relatively common in the French Canadian population and the Cajun community in Louisiana. Carrier screening involves analysis of the enzyme and genetic testing for Tay-Sachs disease, and the detection rate for carriers is approximately 99%. Canavan disease This is a progressive disease of the central nervous system for which there is no treatment. Symptoms begin in infancy and include poor head control, generalized weakness and enlarged head size. Infants also develop seizures, regression of early developmental milestones and severe mental retardation. The disease is typically fatal in childhood. The carrier frequency in the Ashkenazi Jewish population is about 1 in 40. Testing involves analysis of common mutations in this gene and the detection rate is about 97%. Niemann-Pick Disease Niemann-Pick Disease is a severe neurodegenerative condition of infancy which cannot be treated. Symptoms, including loss of brain function and enlargement of the liver and spleen, appear by about 6 months of age. Average life expectancy is about 2-3 years of age. Approximately in 1 in 70 Ashkenazi Jews carries the disease gene. Testing allows a detection rate for carriers of about 95%. Gaucher Disease (Type 1) Gaucher disease is characterized by enlargement of the spleen and liver as well as blood abnormalities including anemia, easy bruising and impaired clotting. In addition, there are orthopedic problems such as bone and joint pain and an increased susceptibility to bone fracture. Some individuals show symptoms in childhood and others remain relatively symptom-free into their 50's or 60's. The severity of symptoms also varies among patients. Enzyme replacement therapy has recently been developed and has been highly effective in reversing some symptoms and reducing the severity of others. Type 1 Gaucher disease is the most common genetic disorder in the Ashkenazi Jewish population, with a carrier frequency of about 1 in 19. Analysis of common mutations allows a detection rate of about 95%. Familial Dysautonomia (FD) Familial Dysautonomia is a severe disease of the autonomic nervous system. Autonomic nerves control functions such as swallowing, sweating, the ability to cry with tears and to sense pain. Individuals with FD may have severe gastrointestinal problems and pulmonary complications such as pneumonia. The carrier frequency in the Ashkenazi population is 1 in 35. Testing for 2 common mutations provides a carrier detection rate of 99.5%. Cystic Fibrosis (CF) CF is a progressive, lifelong condition in which the glands that produce mucus, sweat, and intestinal secretions do not function properly. This results in thick mucus accumulation in the lungs, leading to breathing difficulty and infection. CF also causes poor digestion, and males with this disease are usually infertile. There is no cure for CF. Supportive treatments are available to help improve quality of life and the average life expectancy has improved over the years. CF is found in all ethnic groups. It is most common among Caucasians, Jewish, and non-Jewish alike, with a carrier frequency of about 1 in 25. By testing for some of the more common mutations, 96% of Ashkenazi Jewish CF carriers can be identified as can 80-90% of non-Jewish, Northern European CF carriers. Fanconi Anemia (Type C) Type C Fanconi Anemia is a chronic disease associated with short stature, bone marrow failure, congenital malformations and predisposition to leukemia. For some children, the condition may also involve learning disabilities or mental retardation. The carrier frequency in the Ashkenazi Jewish population is about 1 in 90. Testing provides a carrier detection rate of approximately 95%. Bloom syndrome Bloom syndrome is a condition in which children grow poorly, have frequent infections and may have learning disabilities. As adolescents and young adults, individuals are predisposed to develop common cancers such as breast and colon cancer, and leukemia. The carrier frequency in the Ashkenazi Jewish population is approximately 1 in 100. Testingallows for a carrier detection rate that is greater than 95%. Mucolipidosis Type IV (MLIV) MLIV is a severe neurodegenerative condition that is characterized by a variable degree of growth and psychomotor retardation. In addition, may patients have abnormalities of the cornea and retina. Most patients never develop the ability to speak or walk and remain at the developmental level of 1 to 2 years of age. The carrier frequency in the Ashkenazi population is approximately 1 in 125. Testing provides a carrier detection rate of 96%. What if we are both carriers?If both partners in a couple are identified as carriers for the same disorder, they have a 25% risk with each pregnancy to have a child affected with that disease. They also have a 50% chance that the child will be a carrier, and therefore normal like the parents, and a 25% chance that the child will not inherit a non-working gene at all. If a couple is at risk, prenatal diagnosis is available to determine whether the fetus is affected. This is possible through either chorionic villus sampling (CVS) at 10-12 weeks of pregnancy or amniocentesis in the second trimester of pregnancy. When a carrier couple is identified, a genetic counselor can provide information and support which may be helpful in making important family planning decisions. Learn moreGenetic counseling translates scientific knowledge into practical information that you can use in making family decisions. For more information about genetic counseling, click here or call 414-649-6225. For genetic counseling for cancer, click here.
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