The risk for alcohol dependence is greatly increased if an individual has a variant form of a gene that controls the bitter-taste receptor on the tongue . The taste receptor gene, called TAS2R16 is located on chromosome 7.
Researchers at the Washington University School of Medicine have studied more than 262 DNA samples, before arriving at the conclusion. Each of the family participated in a study called Collaborative Study of the Genetics of Alcoholism (COGA) and had at least three alcoholic individuals.
"In earlier work, we had identified chromosome 7 as a region where there was likely to be a gene influencing alcoholism risk. There's a cluster of bitter-taste receptor genes on that chromosome, and there have been several papers suggesting drinking behaviors might be influenced by variations within taste receptors. So we decided to look closely at these taste receptor genes," said principal investigator Alison M. Goate.
The widespread diversity in the taste receptor gene in the general population allowed the researchers to conduct an in-depth analysis of the genetic variation and further explore the association with risk of alcoholism. The extensive data revealed by the Human Genome project also helped the current research to a great extent.
From cell culture experiments, a single base variation in the taste receptor gene (less response to bitter taste) was found to increase the susceptibility to alcoholism. However, the more common variant form of the gene is very sensitive to bitter taste, conferring a low susceptibility to alcohol dependence. This variant was more likely to occur among African Americans (45%) and was very rarely seen among Caucasians (0.6%).
The authors further intend to extrapolate the results to human taste tests, to find out if the cell culture experiment results would hold good. If this were established, then it could probably pave way for decreasing an individual's tendency to drink by manipulating the taste receptor gene.
"I don't think our result has any implications for the levels of alcoholism within different populations. We know that this polymorphism is more common in African Americans than in Caucasians, but the frequency of alcoholism still can be similar between the two groups because many genes and environmental factors influence risk", concluded Dr. Goate.