Tay-Sachs disease in a Moroccan Jewish family: a possible new mutation.

The parents of a Jewish Moroccan family, in which a previous child had died of Tay-Sachs disease, both proved to be carriers of the mutant gene. Hexosaminidase A activity in the father was similar to that in Ashkenazic heterozygotes, while the mother showed extremely low hexosaminidase A activity in peripheral leukocytes. Amniocentesis was performed on the mother during a subsequent pregnancy; the fetus proved to be affected and the pregnancy was interrupted. Acrylamide isoelectrofocusing of fetal liver and leukocytes of additional family members revealed a variant mutation for Tay-Sachs disease.