Tay-Sachs disease is a genetic disorder that causes an early breakdown of the nervous system. Most people born with this disease do not survive past their third birthday.

What is going on in the body?

Tay-Sachs disease is caused by an enzyme defect. An important enzyme, hexosaminidase A, is not completely formed. Because of this enzyme defect, the body cannot break down a protein that is normally found in cells of the body. When this happens, the protein accumulates in the nerve cells. Then, the nerve cells swell up and degenerate, causing a breakdown of the nervous system.

What are the causes and risks of the disease?

A defective gene causes the enzyme defect that leads to Tay-Sachs disease. The gene is autosomal recessive in character. Autosomal means that the gene is on one of the 22 pairs of non-sex chromosomes. Recessive means that there must be two copies of the gene for the disease to exist.

Tay-Sachs disease is most common among Jews of Eastern European origin, specifically Ashkenazi Jews. Among this group, the carrier frequency is 1 in 30. Among non-Jews the carrier frequency is 1 in 300.