Hexosaminidase A deficiency results in a group of neurodegenerative disorders caused by the accumulation of a cellular lipid called GM 2 ganglioside. This glycosphingolipid accumulates in the lysosomes of many tissues causing progressive weakness and neurological deterioration. Seizures, loss of milestones and loss of vision is also common.

The disorders range from acute infantile onset and rapid decline (classic Tay Sachs disease) to juvenile, chronic and adult-onset forms. The diagnosis of hexosaminidase A deficiency is characterized by absent or profoundly deficient beta-hexosaminidase A activity in the presence of normal beta-hexosaminidase B activity.