Tay-Sachs disease

a recessive disorder most common among persons of Middle and Eastern European Jewish origin, and detectable by prenatal tests. Infants appear normal at birth but become listless and inattentive during the first few months of life. An early sign is an exaggerated startle response to sound. Rapidly progressive symptoms include retardation, paralysis, blindness, seizures, and cherry-red retinal spots; death by age 3 is common. Tay-Sachs disease is caused by abnormally low activity of the enzyme hexosaminidase A, resulting in the formation of sphingolipids in the brain