Tay-Sachs Disease is a progressive and fatal genetic condition that involves a complete deficiency of the hexosaminidase-A (HEXA) enzyme. This enzyme is needed in healthy individuals for the process of hydrolysis of GM2 ganglioside to occur. For individuals with Tay-Sachs disease that lack this enzyme, the fatty substance of GM2 ganglioside accumulates in the brain and leads to the symptoms of the disease.
A mixed, primarily Ashkenazi group, designated as “mixed AJ,” was defined on the basis of other countries of origin with mostly Ashkenazi representation (the United States, Canada, Australia, the United Kingdom, other countries of western Europe, Switzerland, and Latin America). Finally, those with no known country or region of origin were included in the category designated as “unknown.”