Researchers identified previously uncharacterized genetic correlations between alcohol dependence and psychiatric disorders, according to study results published in Nature Neuroscience.
“[Alcohol dependence] is moderately heritable and numerous genome-wide association studies have aimed to identify loci contributing to this genetic variance,” Raymond K. Walters, PhD, of Massachusetts General Hospital and Harvard Medical School, and colleagues wrote. “According to one study, common single-nucleotide polymorphisms are responsible for as much as 30% of the variance in [alcohol dependence], but few have been identified to date.”
The researchers conducted a large genome-wide association study to identify loci related to alcohol dependence and to examine the link between alcohol dependence and other psychiatric/behavioral outcomes. They meta-analyzed genome-wide data on 14,904 individuals with alcohol dependence and 37,944 controls from 28 studies, and stratified data by genetic ancestry. Overall, 46,568 participants were of European descent and 6,280 were of African ancestry.
Analysis identified independent, genome-wide significant effects of diverse ADH1B variants — which prior research has implicated as being responsible for alcohol metabolism — in individuals of European and African ancestries, according to the findings. The researchers observed significant genetic correlations between alcohol dependence and 17 phenotypes, including schizophrenia, ADHD, depression and use of cigarettes and cannabis.
"As we analyze additional alcohol-dependent individuals, we should be able to find additional genomic regions affecting risk for alcohol dependence," Walters said in a press release. "We know there are other DNA regions that have small effects on risk, but it's going to take a large increase in our sample size before we can robustly identify those variants."
In addition, Walters and colleagues found that the underlying genetic factors of alcohol dependence only somewaht overlap with those for alcohol consumption, which emphasizes the genetic difference between pathological and nonpathological drinking behaviors.
“I think it's likely that as the sample sizes of our studies increase, we may find new DNA variants related to these problematic aspects of alcohol dependence but possibly not related to typical drinking,” study author Arpana Agrawal, PhD, professor of psychiatry, Washington University School of Medicine in St. Louis, said in the release.
“The risk conferred by the ADH1B gene is one of the strongest single-gene effects seen in people with a psychiatric illness, but overall, it explains only a small proportion of the risk,” she continued. “Many additional gene variants are making small contributions to alcoholism risk, but to find them, we'll need to study more people.” – by Savannah Demko
Disclosure: Walters reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.