Gene mutation may raise the risk of alcoholism

NEW YORK (Reuters Health) - Researchers have identified a gene variation that seems to influence a person's craving for alcohol. They believe this finding could have important implications for identifying at-risk drinkers as well as for selecting the best treatment for a patient's dependence.

The gene mutation involves a cell structure called the mu-opioid receptor. In previous studies, this receptor has been shown to bind beta-endorphin, a pain-relieving chemical the body releases in response to alcohol intake and other stimuli.

Further research has shown that when the gene variant, or the "G allele," is present, the receptor binds to beta-endorphin more strongly than when the more common "A allele" is present.

Dr. Esther van den Wildenberg, from the University of Maastricht in the Netherlands, and colleagues investigated the impact of the A and G alleles on alcohol craving.

The study, reported in the journal Alcoholism: Clinical and Experimental Research, included 84 men who carried only the A allele and 24 who carried at least one copy of the G allele. Family histories of alcoholism were comparable in each group.

Craving, arousal, and salivation were assessed for each subject after exposure to water or beer in 3-minute trials, the report indicates.

G allele carriers showed significantly more craving than did subjects with only the A allele. Arousal and salivation, by contrast, did not differ significantly between the groups.

In addition, the authors found that G allele carriers were more likely to also report illicit drug use at some point in their lives.

"Studies like this one are important in terms of saying something about how a gene might be involved in alcohol dependence," Dr. Kent Hutchison, an associate professor from the University of Colorado at Boulder who was not involved in the study, said in a statement.

The new findings suggest that mutations in the mu-opioid receptor "may be related to how much a person craves alcohol in a high-risk situation, that is when someone hands him or her an alcoholic drink," he commented. "At this point in time, this gene definitely seems to be one of the key genes related to alcohol dependence. There will undoubtedly be others."

SOURCE: Alcoholism: Clinical and Experimental Research, January 2007.

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