Scientists find gene that can predict alcoholism

Alcoholics could be identified before they develop a physical or psychological dependence on drink, after scientists identified a genetic basis for alcoholism. A study has found a simple genetic difference between people that marks their susceptibility to alcohol.

Apart from developing a test for genetic predisposition to alcoholism, the findings may also help scientists to develop new generations of drug that could be deployed to fight addiction by attacking the genetic "fault" that raises the risk of becoming alcoholic.

Alcoholism tends to run in families but what is not clear is how much of this is due to upbringing and the environment, and how much is due to the inheritance of genes that confer an inherited predisposition to drink addiction.

Robert Kennedy Jr, a member of the American political dynasty that has been plagued by heavy drinking, said his drinking was not something that he had developed by chance. "I feel that in many ways I was born alcoholic," he said in 1997. "It wasn't something I became."

Studies of animals have also shown that some individuals have a genetic predisposition to becoming dependent on alcohol, a toxic substance produced as a metabolic side-product of sugar fermentation.

Scientists have shown for example that it is possible to breed a type of laboratory mouse that actually prefers drinking alcohol to water. They have also shown that this tendency to drink alcohol in preference to water is inherited, and therefore under the control of the genes.

But it is also clear that the genetic predisposition to alcoholism is not caused by a single gene but a group of genes acting together in a complicated way that can be heavily influenced or even overruled by environmental factors, such as conscious control and personal willpower.

The latest study, published in the journal, Proceedings of the National Academy of Sciences, found a link between the physical effects of alcohol – measured by the amount of bodily swaying a person exhibits under the influence – and variations in the DNA closely associated with a gene found on chromosome 15. The gene is also implicated in addiction to nicotine and has been linked both with heavy smoking and the risk of developing lung cancer, said Professor Raymond White, of the University of California at San Diego, who led the researchers.

"There's a concentration on the idea that there are almost certainly a multitude of genes involved in alcohol-related disorders. This particular gene has got a lot of interest because there has been so many things associated with it," he added.

More than 367 siblings in California participated in the study but instead of looking at alcohol dependence, the scientists analysed how each person responded to alcohol intake using a measure of monitoring bodily swaying. It well established that people who can take their drink without feeling any physical effects are at substantially greater risk of being addicted to alcohol, Professor White said.

"Those people who respond less by swaying less actually tend to drink more, and they associate with people who drink more. They seem to adapt to their low response by drinking more, which makes them more likely to become alcoholic," he said.