The most robust genetic finding that alters the risk of developing heavy smoking is in the chromosome 15q25 region, which contains the α5, α3, and β4 nicotinic receptor subunit gene cluster (CHRNA5, CHRNA3, CHRNB4). The SNP rs16969968 is unequivocally associated with smoking behavior (p=5.57 × 10−72) (Tobacco and Genetics Consortium, 2010). Further examination of the chromosome 15 region demonstrates that there are at least two distinct genetic risk variants that contribute to heavy smoking behavior (Saccone et al., 2010a; Tobacco and Genetics Consortium, 2010).
