Tay-Sachs disease

What is Tay-Sachs disease?

Tay-Sachs disease is a genetic disorder that causes permanent brain damage. Tay-Sachs disease is more common in people of Ashkenazi Jewish heritage, a group of people whose heritage is from central and eastern Europe. About 1 in 25 members of this community carry the gene for Tay-Sachs disease.

What are the types of Tay-Sachs disease?

There are 2 main types of Tay-Sachs disease — the infantile form, which is far more common, and the late-onset form.

What are the symptoms of Tay-Sachs disease?

Children with Tay-Sachs disease are healthy when they are born but start developing symptoms from about 6 months, including:

• stopping smiling, crawling or turning over
• losing the ability to grasp or reach out
• blindness
• paralysis
• low muscle tone
• seizures

Children with Tay-Sachs disease usually die by the age of 5.

What causes Tay-Sachs disease?

Tay-Sachs disease is caused by a deficiency in an enzyme that is needed for the brain to function properly. That deficiency is caused by a problem with the HEXA gene.

Tay-Sachs disease is an autosomal recessive disorder, which means that a child must inherit faulty HEXA genes from both parents to have Tay-Sachs disease. If both parents are carriers of faulty HEXA genes there is a:

• 1 in 4 chance that a child will be healthy and not a carrier
• 1 in 4 chance that a child will inherit Tay-Sachs disease
• 1 in 2 chance that a child will be healthy, but a carrier

If one parent is a carrier, there is 1 in 2 chance of a child also becoming a carrier.

Can I be screened for Tay-Sachs disease?

In Australia, there are genetics screening programs offered for high school students of Ashkenazi Jewish heritage, who have a one in 25 likelihood of being carrying a faulty HEXA gene.

The screening is not perfect and will pick up only the most common problems with the HEXA gene.

If your heritage puts you at risk of being a carrier of Tay-Sachs disease, talk to your doctor.

How is Tay-Sachs disease diagnosed?

Tay-Sachs disease may be diagnosed following a clinical examination or by performing biochemical and/or genetic testing on a blood sample.