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 five months of age, when a previously normal child’s development begins to slow and they gradually lose their ability to move. Other symptoms can include muscle stiffness and fits. Eventually, the child will become blind and die prematurely, usually before the age of four.
Other rarer forms of Tay-Sachs disease can begin later in childhood. The severity of these types varies, but they are usually milder than the disease seen in young children.
Read more about the symptoms of Tay-Sachs disease.
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.
Read more about treating Tay-Sachs disease.
What causes Tay-Sachs disease?
Tay-Sachs disease is caused by a genetic mutation. This happens when the instructions that are found in all living cells become "scrambled" in some way, causing one or more processes of the body not to work properly.
In Tay-Sachs disease, a genetic mutation known as the HEXA mutation results in the body not producing an enzyme called Hexosaminidase-A (Hex-A). Without this enzyme, a fatty substance called ganglioside builds up in the cells of the nervous system, causing them to stop working normally, eventually killing them.
Tay-Sachs disease is a type of autosomal recessive inheritance disorder. This means that the child inherits a faulty gene from both parents. Both parents have to be carriers of the HEXA mutation to be at risk of having a child with Tay-Sachs disease. If both parents are carriers, their child will have a 25% chance of developing the condition.
Read more about the causes of Tay-Sachs disease.
Screening
Screening for Tay-Sachs disease is recommended for people in high-risk groups. In England, 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. These screening methods are described as:
- preconception screening – where potential parents are able to check whether they carry the HEXA mutation before starting a family
- antenatal screening - where a foetus is checked to see whether two copies of the HEXA mutation have been inherited, which would cause Tay-Sachs disease to develop
In such a circumstance, the parents would be able to make an informed decision about whether to continue with the pregnancy.
Read more about preventing Tay-Sachs disease.
Who is affected by Tay-Sachs disease?
Due to the success of the screening programmes described above, Tay-Sachs disease is rare in England, occurring in only 1 in every 360,000 births. As a result, most cases now occur in people who are not of Ashkenazi Jewish descent. Both males and females are equally affected by the condition.
