Tay-Sachs Disease

One in thirty Ashkenazi Jews is a carrier of one of the Tay-Sachs mutations. This is about ten times the frequency of carriers in non-Jews. Until 1970 it is estimated that about one in 4,000 births among Ashkenazi Jews was of a Tay-Sachs baby. This produced a great desire to develop a carrier and prenatal test shortly after the enzyme defect was identified. Michael Kaback spearheaded a carrier testing program that, by 2000, had tested well over 1 million Ashkenazi Jews, mainly in North America and Israel. This led to a drop in the incidence of Tay-Sachs disease to less than one-tenth of its previous level.

The testing program has been so successful because it is organized through Jewish community groups, with the active participation of geneticists who conduct the tests. During the 1970s and 1980s the test measured the level of Hex A activity in serum or white blood cells. With the identification of the Ashkenazi mutations, DNA testing came into use. Many geneticists prefer to conduct both types of tests, especially for non-Jews. They find DNA testing useful for its simplicity and exceedingly low error rate, but also recommend enzyme testing to guard against the involvement of a previously undetected mutation that would be missed by the mutation-specific DNA tests.