A DNA variant commonly found in people of European and African descent increases the likelihood of nicotine dependence, a study of more than 38,600 current and former smokers shows.

"This new finding widens the scope of how genetic factors are known to influence nicotine dependence," said Dr Dana Hancock, genetic epidemiologist at RTI International and co-author of the study. RTI, a non-profit research institute based in North Carolina, led the project conducted in the US, Iceland, Finland and the Netherlands by researchers from more than 20 organisations.
"The variant that we identified is common, occurring in 44 percent of Europeans or European Americans and 77 percent of African Americans, and it exerts important effects on gene regulation in human brain, specifically in the cerebellum, which has long been overlooked in the study of addiction," Hancock said. The variant is found in the DNMT3B gene, RTI said in a statement.