April 5, 2011

Genetic Link To Alcohol Consumption: Study

Scientists have identified a gene that appears to play a role in regulating how much alcohol people drink, a finding researchers say could someday lead to better treatments for alcoholism.

The gene, known as "autism susceptibility candidate 2", or AUTS2, has previously been linked to autism and attention deficit hyperactivity disorder (ADHD), although its precise function is not understood.  It is most active in parts of the brain associated with neuropsychological reward mechanisms, suggesting that it might play a part in regulating the positive reinforcement that people feel when they drink alcohol.

The study of more than 47,000 people found that there are two versions of the AUTS2 gene, one three times more common than the other.

Those with the less common version drink on average five percent less alcohol than those with the more common version.

Although alcohol consumption is known to be partially determined by genes, until now the only gene known to make a notable contribution was the gene encoding alcohol dehydrogenase, an enzyme that breaks down alcohol in the liver.

"Of course there are a lot of factors that affect how much alcohol a person drinks, but we know from twin studies that genes play an important role. The difference that this particular gene makes is only small, but by finding it we've opened up a new area of research into the biological mechanisms that control drinking," said Professor Paul Elliott from the School of Public Health at Imperial College London.

The researchers analyzed DNA samples from over 26,000 volunteers to search for genes that appeared to affect alcohol consumption, then compared the findings in another 21,000 people.

The study participants reported how much alcohol they drank in questionnaires.

Once the researchers had identified AUTS2, they looked at how much messenger RNA "“a copy of the gene's code that is used to make a protein "“ was present in samples of donated human brain tissue.

They found that the people with the version of the gene associated with lower alcohol consumption produced more of the messenger RNA, meaning that the gene was more active.

The researchers also investigated strains of mice that had been selectively bred according to how much alcohol they drink voluntarily, and found there were differences in the AUTS2 gene activity levels among different breeds that drink more or less alcohol.

Additionally, blocking the effect of a related gene in fruit flies made the flies less sensitive to alcohol, indicating that AUTS2 seems to be involved in regulation of alcohol intake in a number of different species.

"In this study we combine genetic studies with investigations of animal behavior. Since people drink alcohol for very different reasons, understanding the particular behavior influenced by the gene identified helps us better understand the biological basis of these reasons," said Professor Gunter Schumann from the Institute of Psychiatry, King's College London.

This is an important first step towards the development of individually targeted prevention and treatments for alcohol abuse and addiction."

The findings were published April 4 in Proceedings of the National Academy of Sciences.


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