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Could genetic mutation be behind excessive alcohol consumption?

Scientists believe they have found a genetic mutation that may be behind what makes some people more likely to drink excessively and be alcoholics.

Research on mice published in Nature Communications on Nov. 26 showed that mice with a normal Gabrb1 gene showed no interest in consuming alcohol, and drank little or no alcohol when offered a choice between water or diluted alcohol (about 10 percent ethanol or the alcohol content found in wine).

However, mice with a mutation on their Gabrb1 gene guzzled down the alcohol more freely when it was offered, to the point where 85 percent of daily liquid intake contained alcohol.

"It's amazing to think that a small change in the code for just one gene can have such profound effects on complex behaviors like alcohol consumption,” co-lead author Dr. Quentin Anstee, consultant hepatologist at Newcastle University in England, said in a press release. "We are continuing our work to establish whether the gene has a similar influence in humans, though we know that in people alcoholism is much more complicated as environmental factors come into play. But there is the real potential for this to guide development of better treatments for alcoholism in the future."

The mice with the mutated gene were more willing to do a task -- pushing a lever -- to get more alcohol. They continued to do so over the course of one hour until they were clearly intoxicated and had a harder time with coordination.

The researchers found that the mutation was specifically tied to with two single base-pair points on the Gabrb1 gene. That gene is responsible for coding for the beta 1 subunit, which is integral to the GABAA receptor in the brain. This receptor, which regulates brain activity, is turned on with the presence of an inhibitory chemical messenger (GABA). The GABA system has previously been associated with regulating alcohol intake.

Mice with the mutation had an active GABAA receptor even without GABA available. Their brains ended up with electrical activity in the pleasure zone of the brain, which triggered their desire to drink more alcohol.

The researchers hope to use the knowledge they learned from the mice study to help human alcoholics. About one out of six people in the U.S. have an alcohol problem, according to government estimates.

"Alcohol addiction places a huge burden on the individual, their family and wider society,” Hugh Perry, chair of the Medical Research Council’s (MRC) Neuroscience and Mental Health Board, said in a press release. The MRC partially funded the study. “There's still a great deal we don't understand about how and why consumption progresses into addiction, but the results of this long-running project suggest that, in some individuals, there may be a genetic component. If further research confirms that a similar mechanism is present in humans, it could help us to identify those most at risk of developing an addiction and ensure they receive the most effective treatment."

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