Carrier Testing For Genetic Diseases
 

All around the world certain ethnic groups have been found to have an increased risk for particular genetic diseases. In Jewish people whose ancestors are of Eastern European (Ashkenazi) background, several such inherited diseases are known. These are recessive diseases which means couples are at risk for children with the disorder only when each parent is a carrier of the mutant (disease) gene. The diagram below shows all the different genetic combinations that can be passed to children when both parents are carriers, each having one normal gene (N) and one disease-causing (C) gene. If both parents are carriers, there is 1 chance in 4 for the child to have the disease, or 3 in 4 for a healthy baby.

Genetic testing is very efficient for identifying carriers. The compelling reason for carrier testing is that prenatal diagnosis is available for carrier couples to determine whether or not their fetus has the disease.
 

Genetic Diseases For Which Carrier Testing Is Recommended

Tay-Sachs Disease, is characterized by progressive neurological problems leading to death in early childhood. The carrier rate is 1 in 25 for individuals of Ashkenazi Jewish background. Biochemical testing for enzyme activity can detect almost all Tay-Sachs carriers. Number of Mutations 5

Canavan Disease, like Tay-Sachs, is a degenerative neurological disorder fatal in childhood. Jews of Ashkenazi descent have a 1 in 40 chance of carrying a Canavan gene mutation. Genetic testing can identify approximately 98% of Canavan carriers. Number of Mutations 4

Cystic Fibrosis, the most common lethal genetic disease in the Caucasian population, causes progressive lung disease and digestive complications. The symptoms and course of the disease are variable. One in 29 Ashkenazi Jewish individuals carries a cystic fibrosis mutation and 97% of these carriers can be identified by DNA testing. Number of Mutations 32

Familial Dysautonomia (FD) is a neurological disease characterized by general weakness, feeding difficulties and impairment of those autonomic body functions that control body temperature and blood pressure. Children with FD are frequently hospitalized and have a shortened life span. The carrier rate is 1 in 100 for individuals of Ashkenazi Jewish background. Genetic testing can identify 99% of carriers of FD. Number of Mutations 2

Niemann-Pick Disease, involves progressive mental and physical deterioration with early childhood death. The carrier rate is 1 in 90 in Ashkenazi Jews with a birth incidence in this group of approximately 1 in 32,000. Approximately 95% of carriers can be detected with DNA testing. Number of Mutations 4

Bloom Syndrome, another rare disorder, is characterized by growth retardation and a poor immune system. Affected individuals usually die of cancer before age 30. Approximately 1 in 100 Ashkenazi Jews is found to be a carrier and between 95-97% of carriers are detected with testing. Number of Mutations 1

Fanconi Anemia, with a Jewish carrier rate of 1 in 100, results in severe anemia as well as learning disabilities or mental retardation, and an increased risk of cancer. Number of Mutations 1

Gaucher Disease, is a common disorder among Ashkenazi Jews with 1 in 15 found to be carriers. Symptoms which include anemia, bleeding tendency, and bone pain may be severe in some patients, but mild in others. Gaucher disease can be successfully treated with enzyme replacement therapy. Number of Mutations 5

Mucolipidosis Type IV is a lysosomal disorder which presents with sever neurological and ophthalmologist abnormalities in the first year of life. The carrier rate in Ashkenazi Jews is 1 in 100, and it is inherited as an autosomal recessive disease. Approximately 96% of Ashkenazi Jewish carriers can be detected by DNA analysis. There is no cure or treatment available for Mucolipidosis IV at this time. Number of Mutations 2

Some Additional Information About Carrier Testing

It is important to understand if any of these hereditary diseases has occurred in your family, your chances to be a carrier are probably higher than the population risk.

The diagram below shows the different genetic combinations that can be passed to children when both parents are carriers, each having one normal gene (N) and one disease-causing (C) gene.

It is important to understand if any of these hereditary diseases has occurred in your family, or if you are of Ashkenazi decent your chances to be a carrier are probably higher than the population risk.





Prenatal testing is available for these conditions and sometimes requires testing of the parents as well. Amniocentesis and CVS are the most common types of prenatal diagnostic test. Your healthcare provider will be able to refer you to the proper center for follow-up.

For Additional Assistance

This web site contains general information regarding carrier testing, risk assessment for Ashkenazi Jewish Genetic diseases. However, you may wish to obtain professional counseling prior to having the test.

The individual capabilities and potential of children with Ashkenazi Jewish Genetic disease are considered which you may wish to discuss with your counselor or health care providers. For further information or support use our links page.