Scientists believe some people have a gene that hard-wires them for binge drinking by boosting levels of a happy brain chemical triggered by alcohol.The gene - RASGRF-2 - is one of many already suggested to be linked with problem drinking, PNAS journal reports.The King's College London team found animals lacking the gene had far less desire for alcohol than those with it.Brain scans of 663 teenage boys showed those with a version of the gene had heightened dopamine responses in tests.During a task designed to make them anticipate a reward, these 14-year-old boys had more activity in a part of the brain called the ventral striatum which is known to be involved in dopamine release.When the researchers later contacted the same boys at the age of 16 and asked them about their drinking habits, they found the boys with the 'culprit' variation on the RASGRF-2 gene drank more frequently.The NHS definition of binge drinking is drinking heavily in a short space of time to get drunk or feel the effects of alcohol.Reward responseLead researcher Prof Gunter Schumann explained that while this is not proof that the gene causes binge drinking, and it is likely that many environment factors and other genes are also involved, the findings help shed light on why some people appear to be vulnerable to the allure of alcohol."This appears to be one gene that regulates how rewarding alcohol is for some people."People seek out situations which fulfil their sense of reward and make them happy, so if your brain is wired to find alcohol rewarding, you will seek it out."We now understand the chain of action: how our genes shape this function in our brains and how that, in turn, leads to human behaviour."We found that the RASGRF-2 gene plays a crucial role in controlling how alcohol stimulates the brain to release dopamine, and hence trigger the feeling of reward."So, if people have a genetic variation of the RASGRF-2 gene, alcohol gives them a stronger sense of reward, making them more likely to be heavy drinkers."He said more work was needed to prove this theory - the study only looked at young teenage boys, making it difficult to assess a link with long-term drinking patterns.He said, in the future, it might be possible to offer gene tests to help predict which people are more at risk of alcohol abuse.The findings may also provide a way to make new drugs to block the "reward effect" some people get from drinking.In the UK, about 5,000 teenagers are admitted to hospital every year for alcohol-related reasons.Dr Dominique Florin, of the Medical Council on Alcohol, said: "Anything that adds to our understanding is useful."It's likely that there is a genetic component to problem drinking, but that's not to say that if you have this gene you should never touch alcohol or if you don't have the gene then it will be fine for you to drink."