Tay-Sachs is an inherited genetic disease in which the body does not break down fatty compounds, called gangliosides, as it should. As the gangliosides build up in the brain, they damage the nerve cells, and then these cells cannot function properly.

The gangliosides that build up and cause problems in Tay-Sachs disease are normally broken down by an enzyme called hex A (hexosaminidase A). There are two forms of Tay-Sachs disease, based on whether any hex A is produced or not:

• In the classic or infantile form (the most common type), the body produces no hex A. This form of the disease develops during infancy. A baby with Tay-Sachs disease appears healthy at birth. Symptoms usually first appear 3 to 6 months after birth, beginning with mild motor weakness and occasional twitches of the eye (myoclonic jerks). The baby’s condition progressively gets worse with seizures, blindness, and paralysis. Death usually occurs before the child is 4 years old.
• In late-onset Tay-Sachs (LOTS), the body produces lower-than-normal amounts of hex A. This form of the disease begins between adolescence and the mid-30s. In late-onset Tay-Sachs disease, the symptoms such as clumsiness or mood changes may be subtle at first, later progressing to muscle weakness and twitching, slurred speech, impaired thinking and reasoning, and mental disorders. The life expectancy for a person with LOTS is not known. Depending on how severe the symptoms are, the person may live as long as someone who does not have Tay-Sachs disease.

Treatment for Tay-Sachs disease focuses on controlling symptoms and preparing for the course of the disease. There is no cure. Additional personal and family support measures (such as home care or respite care) may be needed as the disease progresses.