TUESDAY, Sept. 17, 2002 (HealthDayNews) -- If you've ever envied some of your friends who seem to inherently know when to stop drinking, blame the gene pool.
New York researchers confirm that a high percentage of Jews carry a gene that seems to prevent alcoholism.
About 44 percent of the 68 Jewish participants the scientists tested were found to carry a variant of a gene that produces a more active form of alcohol dehydrogenase, the enzyme that catalyzes the first step in the metabolism of alcohol.
Previous research has shown this gene exists among both Asian and Jewish populations, although it is relatively uncommon among Caucasians; estimates are that only 2 percent to 5 percent of Caucasians carry it.
The ADH2*2 variant of the gene ADH2 has been shown to prevent heavy drinking, but this is the first study to show it also exerts an effect on alcohol dependence in Jewish groups, says Deborah Hasin, a professor of clinical public health at Columbia University. Hasin is the lead author of the new study, which appears in the September issue of Alcoholism: Clinical and Experimental Research.
How it exerts this effect is unknown, she admits: "Some effect of the gene prevents them from drinking more, but we don't know how." It may be that people with this gene become inebriated with a smaller amount of alcohol, or that they feel some type of discomfort after consuming a certain amount, she says.
Hasin and her colleagues used a well-validated questionnaire to assess the Israeli Jews' current, past and lifetime level of alcohol dependence. The participants then provided genetic material to be tested for the presence of ADH2*2.
Results suggest the protective effect is stronger among the two more established groups of Israeli Jews, the Ashkenazis (those of European descent and Russian background who arrived before 1989) and Sephardics (those of Middle Eastern and North African backgrounds). Less protected were recent immigrants from the former Soviet Union.
The study findings are consistent with the ideology that genes are not solely responsible for how much a person drinks. Environmental factors also play a role, Hasin says. "I had thought from the beginning that environmental effects might modify biological response," and the findings seem to confirm this, she says. However, this aspect of the study needs to be confirmed in a larger sample.
The majority of those interviewed were male, but women tend to drink less than men and finding a large enough sample of women who drink heavily to provide statistically significant results was outside the scope of the study, Hasin says.
She acknowledges their sample was small, but says the results were statistically significant.
Margit Burmeister, an associate professor of psychiatry and human genetics at the University of Michigan, was not surprised by the study findings. Other research by the same authors has shown similar results, albeit finding that the ADH2*2 allele protects against heavy drinking as opposed to alcohol dependence, she says.
Still, "it's a confirmation of something emerging as a picture," Burmeister says. It's interesting to note that the recent immigrants drank more, she adds.
"If you grow up in a heavy drinking population, it [ADH2*2] doesn't protect you," she says. "There is a lot of environmental influence, no matter what."
Hasin says she and her colleagues next hope to conduct a larger study to confirm the environmental modification of the genetic effect found in this study. They also hope to determine whether ADH2*2 may have any impact on how much a person smokes.
What To Do
Learn more about the problem from the National Institute on Alcohol Abuse and Alcoholism. Need help? The Substance Abuse and Mental Health Services Administration can find a treatment center near you.
