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Tay-Sachs Disease: Still Dangerous

Genetic Counseling

Tay-Sachs disease, also known as GM2 Gangliosidosis, is a disease passed on as a recessive trait. Found dating back to the 15th century, Tay-Sachs has been a deadly disease among a smaller group of people. It is most prevalent among the Ashkenazi Jewish population (mostly Eastern European Jews), but has seen a decline in recent years as a result of extensive testing. However, it is still a very dangerous disease, and needs to be recognized.

It received its name from British ophthalmologist Warren Tay and American Neurologist Bernard Sachs. Tay-Sachs disease is physically the excessive accumulation of fatty acids called gangliosides in the nerve cells in the brain. It is the result of a mutation on the HEXA gene on chromosome 15. Because it is a recessive gene, it requires both parents of a child to be carriers, or infected with the disease so that they may pass the trait on to their child. If both parents are carriers, the child has a 25% chance of receiving the genetic disease.

Tay-Sachs comes in three forms affecting infants, juveniles, and adults. The most fatal, and common, of the three is Infantile TSD. A child infected with the disease will live the first six months of its existence normally, but will then face wave after wave of mental and physical deterioration. The child may become blind, deaf, and unable to swallow until death (usually before the age of three). The other two forms of tay-sachs are both extremely rare, but still possible.
The buildup of fatty acids which results in the disease is a result of a lack of an enzyme called hexosamindase A.

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Anybody that takes a simple blood test is able to test for the recessive gene. However, the stopping the spread of the disease is another matter. Screening for Tay-Sachs has been a great success in the emerging field of genetic counseling. Because of its predominance over Jews, Jewish communities have taken strong action to try to stunt the growth of the disease. Israel has in effect become the first country to offer free genetic screening and counseling for all couples. It is also the leading center for research on genetic disease.

Steps have been taken to try to reduce the threat of Tay-Sachs among the Jewish population. For instance, prenatal diagnosis and selective abortion are now viable options for parents. If both parents know that they are carriers, they can test their child to see if it has the homozygous recessive trait. However, other options are available. For instance, if individuals register for an anonymous screening program, organizations are able to implement measures that advise couples of the risk of continuing their relationship.

Finally, couples can choose to take part in a more costly procedure, preimplantation genetic diagnosis; a program where embryos are created outside the womb and implanted only if they are free of the recessive gene. These steps have found results as is seen in statistics. Of 10 babies born with Tay-Sachs in North America in 2003, none were a part of Jewish families. Furthermore, only one was born in Israel.

However, if a child is found to have Tay-Sachs, alternate measures are available. Although they do not stop the disease, they slow it down. With continuing research hope lies in the form of several new alternatives including enzyme replacement therapy, gene therapy, and metabolic therapy. Today, one in 27 Ashkenazi Jews is a recessive carrier. French Canadians and the Cajun community of Louisiana also have a similar dilemma.

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Irish Americans have a 1 in 50 chance of being a carrier. Finally, in the general population, the probability of being a carrier is about 1 in 300. Extensive research over the issue has lead to advances in the research of other genetic diseases as well. Although it has not yet been cured, it is being worked on at a rapid pace, and it is slowly being eradicated from the population, generation after generation.

Works Cited:
“Tay-Sachs disease – Wikipedia, the free encyclopedia.” Wikipedia URL: (http://en.wikipedia.org/wiki/Tay-Sachs_disease)