CHRNA5 and lung cancer: Genome-wide association studies (GWAS) have identified a susceptibility locus for human lung cancer at chromosome 15q24-25, which contains the CHRNA3, CHRNA5, and CHRNB4 genes encoding the α3, α5, and β4 subunits of nAChRs (Amos et al., 2008; Hung et al., 2008).