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Tay-Sachs disease is a fatal genetic disease caused by a lack of the enzyme hexosaminidase A. It affects infants and young children, causing paralysis, blindness, and death. Those of European Jewish, Cajun, or French Canadian ancestry are at higher risk and should seek genetic counseling. There is currently no cure, but gene therapy is being researched.
Tay-Sachs disease is a devastating and fatal disease caused by a lack of the enzyme hexosaminidase A (hex A). Tay-Sachs is of genetic origin. Everyone who has Tay-Sachs gets it from two parents who carry a recessive gene for the disease. These parents do not have Tay-Sachs because the disease in its most common forms, infantile and juvenile Tay-Sachs, causes death before the children reach adulthood.
With Infant Tay-Sachs, newborns appear perfectly healthy and in line with development. Between four and six months, these babies begin to lose the ability to continue developing and actually lose previously acquired skills, such as smiling or recognizing their parents’ voices. Eventually, the disease causes complete paralysis, blindness, and death, usually by the age of five.
The cause of this deterioration is that hex A is not there to break down the fatty tissues in the brain and nerves. Failure to metabolize these substances gradually results in the above symptoms and death, as the brain and nerves are increasingly damaged by the fatty tissues.
Young Tay-Sachs causes affected children to develop symptoms around age three, although this can range from age two to five. The progression of the disease is very slow, taking up to 12 or 13 years before death occurs. Parents are heartbroken to see their children gradually lose previously acquired functions such as talking and walking. Children with juvenile Tay-Sachs may still have the ability to understand, but speech, if any, will be slurred and unintelligible in later stages. Young Tay-Sachs is also associated with more pain, as he experiences frequent muscle spasms and cramps.
On rare occasions, an adult will develop a hex A deficiency. Their disease will follow a similar course to those with juvenile Tay-Sachs. Predictors of this deficiency in adults are not well defined.
Tay-Sachs is often associated with European Jews. They have the highest rate of being carriers of the gene responsible for Hex A deficiency. However, not only Jewish children get Tay-Sachs. The existence of the disease has been noted in some French Canadians. Additionally, those with Cajun ancestry are more at risk.
A parent who is a carrier has a 50% chance of passing the carrier gene on to their children. When both parents are carriers, each child has a 25% chance of being born with Tay-Sachs. Each child will also inherit a gene to carry the disease. Tay-Sachs can be diagnosed with chronic villus sampling during the early part of pregnancy. Many who later receive a positive diagnosis are faced with the difficult decision of whether to terminate a pregnancy and the life of their baby at this point, as the outcome of the disease is likely to be fatal.
Those of European Jewish, Cajun, or French Canadian ancestry are advised to have genetic counseling before having children. The recessive gene for Tay-Sachs can be identified through blood work, and then prospective parents can evaluate possible risk factors for having a child with Tay-Sachs. There is currently no cure for Tay-Sachs. However, since this enzyme deficiency is related to genes, researchers are looking at gene therapy as a possible cure in the future.
