A cluster of genes on chromosome 11 could be partially responsible for alcohol dependency, researchers say. Indiana University School of Medicine and the National Institute on Alcohol Abuse and Alcoholism researchers conducted a genome-wide association study as part of long-range research on alcohol dependence, and found that a cluster of genes on chromosome 11 may incrementally add to a person's risk for developing alcohol dependency.
Indiana's Howard Edenberg says that evidence suggests this cluster has an impact on individual's dependence. In the study, about 1 million genetic polymorphisms were analyzed in about 1,400 unrelated individuals. Edenberg says they followed up on the most significant variants to see if they were associated in families, if they were expressed in the brain, or if their expression patterns were altered by alcohol. And several were.
"A number of the SNPs were in that region, and in that region are some genes that are expressed in brain," Edenberg says about his study, which appears in this month's issue of Alcoholism: Clinical & Experimental Research. The evidence is suggestive, he says, but is only a small piece of the puzzle.
The chromosome 11 cluster is not the sole genetic cause of alcohol dependence. The study also provided support for the findings of other researchers who have previously discovered genes that affect a person's risk for alcohol dependency. "There's a fairly small increase — about 1.2 to 1.4 percent — in the risk of developing alcohol dependency with this cluster of genes," Edenberg says. "This is a relatively small impact. But our current understanding is that it's the accumulated effect of these small-impact genes, as well as a person's environment, that add to the risk."
This study is only one part of a much larger plan. Edenberg's group will work with other researchers to replicate the study's findings and test others' results. The groups plan to examine how a person's risk for alcoholism is related to the variations in each gene identified, and to start functional studies of how the genetic variations affect cells and tissues. "What I think is going to be the most important impact of these studies is that they're going to lead us into the biochemical and neurochemical pathways that modulate risk," Edenberg says. "Then we can explore pharmaceutical remedies for alcohol dependence."