Tay-Sachs

Tay-Sachs disease is a hereditary disease caused by a gene mutation. People with this defective gene does not have an enzyme (i.e., a "throttle" of a chemical reaction in the body) important designated by hexosaminidase A (HEXA), which allows combat the formation of a type of fat called GM2 ganglioside. As a result, it accumulates in the brain, eventually damaging nerve cells and cause neurological disorders.

Children with Tay-Sachs disease usually manifests the earliest signs of disease between 3 and 6 months of age. These children may be deaf, blind and with cerebral, ending in most cases die around the age of five.

Tay-Sachs disease is an autosomal recessive inherited disease, meaning that the newborn inherited from each of his parents copy of the defective gene. The child's parents do not actually suffer from the disease but are carriers of the gene for Tay-Sachs and transmit it to the baby. If both parents are carriers of the mutated gene, there is one chance in four of his son inherit this gene from both and will develop Tay-Sachs.

Tay-Sachs disease has a higher incidence in Ashkenazi Jews, and about one in 30 individuals in this ethnic group has the gene. Some non-Jewish ethnic groups also have a higher probability of being carriers of the disease, including groups of French-Canadian descent, mangrove inhabitants of Louisiana, or belonging to the Amish communities of Pennsylvania.

In addition to the classical form of the disease cited above, which usually leads to death in children, there are two types which are usually included in the definition of Tay-Sachs since they affect the same gene:

• a juvenile form of the disease which is manifested normally between two and five years old and whose symptoms are similar to those of Tay-Sachs classical, with the patient's death occurs between 15 and 20 years. If symptoms arise after the fifth year of life may be more mild.

• An adult form, very rare, called Tay-Sachs late, which resembles the chronic form of the disease but that comes later in life, between adolescence and "thirties".

Tay-Sachs disease may also be called Type 1 GM2 gangliosidosis.

Prevention

The advice from a geneticist before attempting a pregnancy help both parents understand the chances that they will generate a child suffering from Tay-Sachs. If both prospective parents are carriers of the gene and if a woman is pregnant, an amniocentesis or chorionic villus biopsy can determine whether the fetus has the disease or not.

Treatment

There is no effective treatment for Tay-Sachs. As with other fatal diseases, treatment aims to relieve symptoms and provide comfort to the child and family.