Tay-Sachs disease (TSD) is a fatal condition caused by a deficiency of the enzyme hexosaminidase A (Hex-A).
The genetic defect in Tay-Sachs disease results in the lack of an enzyme called hexosaminidase A.
Juvenile hexosaminidase A deficiency: Symptoms appear between ages two and five; the disease progresses more slowly, with death by about 15 years.
Chronic hexosaminidase A deficiency: Symptoms may begin around age five or may not occur until between 20 and 30 years of age.
Tests to determine the presence and quantity of hexosaminidase A can be performed on the blood, specially treated skin cells, or white blood cells.