Tay-Sachs disease - Testing for Tay-Sachs disease

Tests can be carried out to check if you are a carrier of Tay-Sachs disease or to diagnose the condition after birth.

Preconception screening

Screening for the HEXA mutation that causes Tay-Sachs disease is recommended if you are planning to start a family and you are in a high-risk group for developing the disease.

In the UK, two main groups of people are thought to have a high risk of developing the condition:

• people of Ashkenazi Jewish descent – this applies to most people of Jewish descent in the UK 
• people with a known history of Tay-Sachs disease in their family

Screening involves checking yourself and your partner for the HEXA mutation using a blood test. If you both test positive, you have a 25% chance of conceiving a baby who develops Tay-Sachs disease.

Antenatal screening

It is also possible to test a foetus for Tay-Sachs disease during pregnancy (antenatal screening) using tests such as:

• chorionic villus sampling (between weeks 10 and 13 of pregnancy) – where a sample of cells is taken from the placenta to be tested
• amniocentesis (between weeks 15 and 20 of pregnancy) – where a needle is used to remove amniotic fluid for testing

If a diagnosis of Tay-Sachs disease is confirmed, you can choose to terminate or continue the pregnancy.

Tests after birth

A diagnosis of Tay-Sachs disease would be strongly suspected if a young baby develops symptoms that are closely associated with the condition, such as an exaggerated response to sudden noises and red spots at the back of the eyes.

Blood tests can also be carried out to check if the body is producing the Hexosaminidase-A (Hex-A) enzyme (see causes of Tay-Sachs disease for more information).

If there is any doubt about the diagnosis, it can usually be confirmed by taking a blood sample and extracting DNA from it to check for the HEXA mutation.

Receiving the diagnosis

Being told that your baby has a fatal and incurable condition is a devastating experience, and it's likely you will experience profound feelings of grief, bereavement and even guilt.

The National Tay-Sachs & Allied Diseases Association is an American foundation for people affected by Tay-Sachs disease. Its website has information about ways to treat the symptoms, as well as useful advice about coping with the emotional impact of the condition.

The UK-based charity Genetic Alliance UK also provides information and services for people who have been affected by genetic conditions such as Tay-Sachs disease, as do organisations such as Climb.

You may also find it useful to read more about caring for a child with a terminal illness.