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Tay-Sachs Disease

Definition

Tay-Sachs disease (TSD) is a fatal genetic disorder. It occurs when harmful amounts of ganglioside GM2, a fatty substance, accumulate in and progressively destroy the brain's nerve cells. Given the best of care, all children with TSD die by the age of five.

Causes

TSD is caused by the absence of the enzyme hexosaminidase A. This enzyme breaks down GM2. TSD is controlled by a pair of genes on chromosome 15. TSD carriers have one copy of an active gene and one copy of an inactive gene. TSD occurs when both parents pass on the inactive gene to their child.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

Having parents who are carriers of the TSD gene
Race: of eastern European (Ashkenazi) Jewish descent

Symptoms

Babies with TSD may seem to develop normally until about 3-6 months of age when there is an arrest of development and symptoms begin to occur. Symptoms may include:

Floppy body position
Shrill cry
Enlarged head
Vision loss or blindness
Deafness
Difficulty swallowing
Slurred speech
Muscular difficulties, such as:
- Spastic muscles
- Weakness or paralysis
Mental retardation
Seizures

Diagnosis

The doctor will ask about your child's symptoms and medical history, and perform a physical exam. The doctor may examine your child's eyes to look for a cherry red spot on the retina that may occur in TSD.

A blood test to measure hexosaminidase A activity can also help diagnose TSD.

Treatment

There is presently no treatment for TSD.

Prevention

There are no known ways to prevent Tay-Sachs disease once a person is born. If you are a carrier of the inactive gene that causes TSD, you can talk to a genetic counselor before deciding to have children.