Ashkenazi Jewish Carrier Testing

This test is used to determine identification of carriers for four Jewish heritage diseases, specifically Canavan Disease, Cystic Fibrosis, Familial Dysautonomia, and Tay-Sachs disease.

Canavan disease is an autosomal recessive progressive leukodystrophy that often leads to death in the first decade of life. Leukodystrophies are a group of rare genetic disorders that affect the central nervous system by disrupting the growth or maintenance of the myelin sheath that insulates nerve cells.

Canavan disease is caused by a deficiency of the enzyme, aspartoacylase (ASPA). Canavan disease is more common in the Ashkenazi Jewish population where about 1 in 40 persons is estimated to be a carrier.

This test identifies carriers and affected individuals for four mutations associated with Caravan disease: E285A, Y231X, 433-2A>G, and A305E.

Couples who are both carriers have a one in four risk of having a child with Canavan disease.

• A305E is the Canavan mutation found among individuals of non-Ashkenazi Jewish ancestry.
• This test detects 98% of mutations responsible for Canavan disease in Ashkenazi Jews, and 60% of mutations in non-Jewish Caucasians.

Cystic fibrosis (CF) is a common genetic disorder resulting in chronic pulmonary and gastrointestinal/pancreatic disease. There is wide variability in clinical symptoms of cystic fibrosis.

This test is used to help determine affected or carrier status for the 32 most common Cystic Fibrosis mutations.

CF is inherited in a recessive manner, which means that both parents must be carriers to have an affected child. When both parents are carriers, there is a 25% chance with each pregnancy that the child will be affected. Genetic counseling and CF molecular testing are recommended for the reproductive partners and at-risk family members of CF carriers.

Familial dysautonomia (DYS), the Riley-Day syndrome, is an autosomal recessive disorder characterized by developmental loss of neurons from the sensory and autonomic nervous system.

It is limited to the Ashkenazi Jewish population, where the carrier frequency is 1 in 30.

Tay-Sachs is an inherited disease in which the body cannot properly break down fatty substances. This leaves the fatty substances to collect in the brain's nerve cells, causing damage.

Tay-Sachs disease is tested for by measuring levels of an enzyme called hexosaminidase A (hex A) in the blood. This test measure levels of hex A, determining if an individual has Tay-Sachs disease or is a carrier of the disease.

This test can also be used to determine if an individual has a condition in which they cannot make either hex A or hex B, called Sandhoff's disease.