Tay-Sachs: GM2 Gangliosidosis

by: Tai Robie

Brief Summary

The Tay-Sachs disease is extremely rare, it is rare enough for only 16 people in the US to be born with it each year. The Tay-Sachs gene is most commonly found in the Ashkenazi Jews, Sephardic Jews, French-Canadians, Irish, and the Cajun communities. The Ashkenazi Jews, French-Canadians, and Cajuns all have a .037% (1/27) carrier rate. The Irish have a .02% (1/50) carrier rate. The Sephardic Jews have a .004% (1/250) carrier rate. These are the most common percentages in populations, so you can see how rare this disease is. Individuals with the disease die at about age 5, so there aren't any celebrities who currently have it

Symptoms & Biology of Disease

When one has the disease they lack hexosaminidase A, which is a protein that helps break down gangliosides, a group of chemicals in the nerve tissues. These chemicals start to build up and destroy cells, mainly brain cells. The baby will act normal for about 3 to 6 months and then the development begins to slow and the muscles weaken. The baby will then start to lose motor skills (Sitting & crawling). The baby will suffer from vision failure, severe hearing loss, paralysis, seizures, mental retardation, and become unresponsive to the environment. The individual will only survive to early childhood...

Mutation and Inheritance

Frequently there are situations where the patient has Tay-Sachs and a frame shift mutation. The Tay-Sachs gene is recessive. Since the person with Tay-Sachs dies before he or she can reproduce, there will never be homologous parent with Tay-Sachs. This means both of the parents have to be carriers of the gene. The highest possibility, and only possibility, of two carriers to have a homologous baby (with the Tay-Sachs gene) is 25%. This is why the gene is so rare, it kills the homologous organisms before they can reproduce so the only way to increase the number of people who have it is through carriers.

Diagnosis/Treatment

If you didn't do any tests you may start to notice slower development at 3 to 6 months and the muscles will start to weaken, as said in the first section. Prenatal tests can diagnose Tay-Sachs gene. Genetic testing is generally done when both members of a couple are carriers. You can test if you are a carrier if you take an enzyme analysis test. It tests the level of Hex-A in the blood regardless of ethnic backgrounds.