Screening for carriers of Tay-Sachs disease: A community project.

Heterozygotes for Tay-Sachs disease can be distinguished by measuring the serum hexosaminidase activity and calculating the percentage of the heat-labile (A) form. We tested 7565 Ashkenazi Jews in Metropolitan Toronto and found a carrier frequency of 0.071. This figure was similar to the predicted frequency on the basis of caseload over a five-year period. We also found that 15% of women taking oral contraceptives were false-positive carriers. As with pregnant women, these false-positive carriers could be distinguished from true carriers by assaying leukocyte hexosaminidases.