Overselling genetics

From the Herald, under the headline “Could you have the binge drinking gene?”

It’s long been known that a penchant for alcohol may be in the genes, and scientists say they may now be a step closer to understanding why.

They have found that a faulty gene may cause binge drinking – and that mice with the mutation overwhelmingly prefer the taste of alcohol to water.

This story is from the Daily Mail again; the Herald’s own reporters write better medical science stories.

In fact, the research is looking at mice to see the effect of mutating one of the genes encoding something called the GABA-A receptor. There’s some genetic evidence that differences in this gene are related to alcohol dependence (not binge drinking, which isn’t the same thing) in humans, and the researchers are interested in how the effect might work. They say

Our understanding of the genetic and molecular basis of alcohol dependence is incomplete. Alcohol abuse has long been associated with facilitation of neurotransmission mediated by the brain’s major inhibitory transmitter, GABA, acting via GABAA receptors (GABAARs). Recently, a locus within human chromosome 4, containing GABAAR subunit genes… associated with alcohol dependence in humans. … However, the neurobiological basis by which genetic variation translates into alcohol abuse is largely unknown.

This research into how the genetic differences might work is interesting and has potential applications in treatments for addiction, but we know that variants in this particular gene predict almost nothing about alcohol dependence in humans. That’s typical in modern large-scale genetics: genetic variants common enough to study in large numbers of people usually have very small effects, and they are important because they provide tiny points of light illuminating the complex biological mechanisms of health and disease.

You can get another useful bit of context by searching on “binge drinking gene”

• Daily Mail, March 2011: It has long been believed that alcoholism runs in the family – now scientists have pinpointed why. They have identified a binge-drinking gene, offering new hope in combating the growing social problem, it was revealed today.
• Daily Mail, December 2012:  A newly discovered addiction gene could be fuelling teenage binge-drinking, research suggests. The mutant version of the RASGRF2 gene makes the brain more sensitive to habit-forming rewards such as alcohol, studies have shown.

We were clearly due for identifying the binge drinking gene again about now. But if you want to know if you are at risk of binge drinking, counting your drinks will be much more informative than measuring your genes.