Tay-Sachs Carrier Test in California

What this test measures

Tay-Sachs disease is an inherited condition caused by changes in the HEXA gene, which carries instructions for the enzyme hexosaminidase A. This enzyme helps break down a fatty substance called GM2 ganglioside in nerve cells. When the enzyme is missing or reduced, the substance builds up and damages the nervous system. The condition is passed in an autosomal recessive pattern.

The test measures hexosaminidase A activity in a blood or serum sample. In carrier screening, reduced activity can suggest a person carries one altered copy of the gene, while a diagnosis involves more detailed enzyme and genetic testing. Because enzyme levels can be affected by other factors, abnormal results are usually confirmed with additional testing, including DNA analysis.

The test may be ordered for people with a family history of Tay-Sachs disease, for couples planning a pregnancy who want carrier screening, or for individuals in groups where certain gene changes are more common. Carriers are usually healthy and may not know their status. Genetic counseling is recommended before and after testing to explain results and options.