Tay-Sachs disease

Tay-Sachs disease is a rare and usually fatal genetic disorder that causes progressive damage to the nervous system.

In the most common form of the condition, symptoms usually begin at around six months of age, when a previously normal child's development begins to slow and they gradually lose their ability to move.

The most noticeable early symptoms include a child being excessively startled by sudden noises and red dots appearing near the middle of the eyes.

The child will then develop problems such as muscle weakness, increasing loss of vision, loss of hearing and seizures.

Most children with the condition die by the age of three to five years.

Less common forms of Tay-Sachs disease can begin later in childhood or even early adulthood. These usually progress less rapidly than the disease seen in very young children. However, only in rare cases is life expectancy not affected.

Read more about the symptoms of Tay-Sachs disease.

What causes Tay-Sachs disease?

Tay-Sachs disease is caused by two genetic mutations. This happens when the instructions found in cells become "scrambled" in some way, causing one or more processes of the body to not work properly.

In Tay-Sachs disease, a genetic mutation in the HEXA gene results in the body not producing an enzyme called Hexosaminidase-A (Hex-A). Without this enzyme, a fatty substance called GM2 ganglioside builds up in the cells of the brain and nerves, causing them to stop working normally and eventually destroying them.

Both parents have to be carriers of a HEXA mutation to be at risk of having a child with Tay-Sachs disease. If both parents are carriers, each child they have will have a 25% chance of developing the condition.

Read more about the causes of Tay-Sachs disease.

Testing for Tay-Sachs disease

Screening for Tay-Sachs disease is recommended for people in high-risk groups before planning a family. In the UK, this includes people of Ashkenazi Jewish descent and anyone with a history of the condition in their family.

Screening can take place at two points, either before or after a baby is conceived. If the condition is diagnosed in an unborn baby, the parents can decide whether to continue with the pregnancy or not.

Read more about testing for Tay-Sachs disease.

How is Tay-Sachs disease treated?

There is currently no cure for Tay-Sachs disease, so treatment involves making the child feel as comfortable as possible by treating the associated symptoms.

Research is being carried out into possible cures for Tay-Sachs disease, but this is still at an early stage.

Read more about treating Tay-Sachs disease.