What Your Test Results Mean:

Carriers typically show no symptoms of Tay-Sachs disease; however, carriers are at an increased risk of having a child with Tay-Sachs disease. Risk for current or future pregnancies is dependent on your partner’s carrier status.

Disease Explained:

Tay-Sachs disease is an inherited metabolic disorder in which harmful amounts of a glycosphingolipid called GM2 ganglioside accumulate within lysosomes, or recycling compartments, of cells. Individuals with Tay-Sachs disease do not produce enough of one of the enzymes, β-hexosaminidase A, needed to break down GM2 ganglioside. Over time, this excessive storage in the lysosomes can cause permanent cellular and tissue damage, particularly in the spleen, liver, bone marrow, and rarely, the brain.

While juvenile, chronic, and adult-onset forms of hexosaminidase A deficiency have been described, Tay-Sachs disease is the most severe form of hexosaminidase A deficiency. Individuals with Tay-Sachs typically have normal development in the first few months of life followed by regression of developmental milestones within the first year. With time, decreasing visual attentiveness, unusual eye movements, seizures, and progressive enlargement of the head become apparent. Life expectancy is typically between two and four years.

Treatment is mostly supportive and directed to providing adequate nutrition and hydration, managing infectious disease, protecting the airway, and controlling seizures.

How the Genetics Works:

The clinical features of Tay-Sachs disease can be explained by pathogenic variants in the HEXA gene. In general, individuals have two copies of the HEXA gene. Carriers of Tay-Sachs disease have a single variant in one copy of the HEXA gene while individuals with Tay-Sachs disease have variants in both copies of their genes, one inherited from each parent.