Genetic variants influence several measures of smoking behavior, report three papers published this week in Nature Genetics. The studies each performed genome-wide association studies for measures of smoking behavior reflecting smoking initiation, dependence, and cessation. The strongest associations were found for the number of cigarettes smoked per day, a measure of smoking dependence.
The three studies collectively analyzed data from over 140,000 individuals with several recorded measurements of smoking behavior. Clyde Francks and colleagues report a genome-wide meta-analysis for smoking quantity that replicates a previous association at the CHRNA3-CHRNA5-CHRNA4 locus on chromosome 15. This includes genes encoding nicotinic acetylcholine receptor subunits. The two studies from Helena Furberg, Kari Stefansson and their respective colleagues also found genetic regions associated to number of cigarettes smoked per day that include candidate genes encoding additional nicotinic acetylcholine receptor subunits, CHRNB3 and CHRNA6, as well as nicotine metabolizing enzymes CYP2A6 and CYP2B6.