Gene has 'big effect' on alcoholism, how quickly you get drunk

Over the past several decades, studies of college students have shown that such individuals (who get tipsy after a drink or two) are one-third to one-half as likely to develop alcoholism as those who drink and drink and drink before they feel drunk.

Now scientists have identified a gene that has a "big, big effect" on how people respond to alcohol, says Kirk Wilhelmsen, senior author of a paper posted Tuesday by the journal Alcoholism: Clinical and Experimental Research. About 10% to 20% of the population carry a version of the gene that makes their brains especially sensitive to alcohol.

The gene carries the blueprint for an enzyme called CYP2E1, known to be involved in metabolizing ethanol alcohol as well as other molecules, such as the pain-reliever acetaminophen, or Tylenol, and nicotine. People who carry the version of the CYP2E1 gene linked to increased sensitivity to alcohol produce more of the enzyme.

The CYP2E1 ezyme works in the brain, not the major player in alcohol metabolism, says Wilhelmsen, a genetics professor at the University of North Carolina-Chapel Hill School of Medicine. Another enzyme, in the liver, "does most of the heavy lifting" in breaking down alcohol, he says. Apparently, though, CYP2E1 affects how sensitive the brain is to alcohol, perhaps because it — unlike the enzyme in the liver — generates free radicals, tiny molecules that can damage cells.

Gene has 'big effect' on alcoholism, how quickly you get drunk