Definition

Tay-Sachs disease (TSD) is a fatal genetic disorder. It occurs when a fatty substance builds up in the brain. This causes progressive destruction of the brain. There are three forms:

• Infantile-onset
• Juvenile-onset
• Adult-onset

Causes

TSD is caused by the absence of an enzyme. This enzyme is needed to break down a fatty substance called GM2. As a result, GM2 builds up. The build up in the brain causes damage.

TSD occurs when both parent pass on the faulty genes. A person can have just one copy of the faulty gene. In this case, there are no symptoms. The person is called a carrier.

Genetic Material

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Risk Factors

Factors that increase your chance for TSD include:

• Having parents who are carriers of the TSD gene
• Race: Eastern European (Ashkenazi) Jewish descent
• TSD is also frequently found in French Canadian and Cajun populations

Symptoms

Babies with TSD may seem to develop normally until about 4 to 5 months of age. There is then an arrest of development. Symptoms begin to occur. Symptoms may include:

• Floppy body position
• Shrill cry
• Decreased eye contact
• Increased startle reaction
• Loss of motor skills
• Enlarged head
• Vision loss or blindness
• Deafness
• Difficulty swallowing
• Slurred speech (juvenile-onset form)
• 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. A physical exam will be done. The doctor may examine your child's eyes to look for a cherry red spot on the retina. Your doctor may also order:

• Blood test—to measure hexosaminidase A activity

Treatment

There is presently no treatment for TSD. However, research is ongoing.

Prevention

There are no known ways to prevent Tay-Sachs disease. If you are a carrier of the gene that causes TSD, you can talk to a genetic counselor before deciding to have children. Prenatal testing during the first trimester is available.