Smoking is influenced by genetic and environmental factors.1, 2 Genome-wide association studies (GWAS) in populations of European ancestry have identified genetic variation associated with smoking behaviors, including smoking initiation (SI), smoking quantity and smoking cessation (SC). An initial, large (n=10 995) GWAS of smoking quantity identified associations with genetic variants in the nicotinic acetylcholine receptor α5, α3 and β4 subunit cluster on chromosome 15q25.1.3 Genome-wide meta-analyses in three large consortia (n=74 053, 31 226 and 41 150) of smoking behaviors confirmed the finding at 15q25.1 and refined the association signal within the locus.4, 5, 6 Additional studies in diverse populations also have revealed independent signals in this region, suggesting multiple biologically functional variants.7, 8 This locus has also been reported as a susceptibility locus for lung cancer; however, whether this effect is independent of smoking behavior is unclear.9, 10 Additional regions have been identified for smoking quantity (CHRNB3/CHRNA6) on 8p11,4 CYP2A6 on 19q134, 6 and LOC100188947 on 10q256), SI (BDNF on 11p13)6 and SC (DBH on 9q34).6
