SNPwatch: Two Vices, One SNP – Drinking and Smoking Behavior Both Linked to Nicotine Receptor Genes

SNPwatch gives you the latest news about research linking various traits and conditions to individual genetic variations. These studies are exciting because they offer a glimpse into how genetics may affect our bodies and health; but in most cases, more work is needed before this research can provide information of value to individuals. For that reason it is important to remember that like all information we provide, the studies we describe in SNPwatch are for research and educational purposes only. SNPwatch is not intended to be a substitute for professional medical advice; you should always seek the advice of your physician or other appropriate healthcare professional with any questions you may have regarding diagnosis, cure, treatment or prevention of any disease or other medical condition.

As anyone who indulges in both smoking and drinking can tell you, the two are a natural – if unhealthy – combination. Now research suggests that some people possess a single genetic variation that makes them prone to greater indulgence in both vices – and the attendant health risks.

Several research papers published in the last year or so show that a cluster of genes on chromosome 15 encoding nicotinic receptors, which regulate the brain’s response to nicotine, are related to smoking behavior. We cite one of those papers in the 23andMe Health and Traits entry for Nicotine Dependence – it shows that on average, smokers with an A at both copies of the SNP rs1051730 light up once more per day compared to those with the AG or GG genotype.

The authors of the new study, which appears in the latest issue of the Proceedings of the National Academy of Sciences, noted that connection between chromosome 15 and nicotine dependence. They also observed the fact that twin studies have established a genetic connection between smoking and alcohol abuse and that experiments show mice consume less alcohol when treated with a drug that blocks nicotinic receptors.

So the researchers, who were from the Ernest Gallo Clinic and Research Center in Emeryville, Calif., and the University of California, San Diego, reasoned that the very same genetic variations recently associated with smoking behavior could influence drinking as well. To test that hypothesis, they genotyped 367 participants aged 18 to 29 and tested them on various measures of alcohol response. Those with an A at both copies of rs1051730 were better able to maintain their coordination after drinking a given amount of alcohol and reported feeling less drunk compared to those with either the AG or GG genotypes. The researchers also found a second SNP nearby on chromosome 15 – rs8034191 – that was also linked to alcohol sensitivity. In that case, having a C at both copies of the SNP decreased a person’s response to alcohol. 23andMe customers can check their own genotypes at both SNPs using the Browse Raw Data feature.

Some people might consider it good news to learn that they have a genetically enhanced ability to hold their drink. But a reduced response to alcohol increases a person’s risk of alcohol abuse. So in addition to causing people who do smoke to light up more often, this particular genetic signature also appears to threaten health by increasing a drinker’s chances of developing problems with alcohol.