This review examined the evidence for the association of cholinergic and nicotine metabolism genes with smoking cessation and therapeutic response. Although SNPs in the CHRNA5-CHRNA3-CHRNB4 gene cluster have reproducible associations with smoking heaviness, evidence supporting the role of the CHRNA5-CHRNA3-CHRNB4 gene cluster in smoking cessation is mixed. There is initial evidence for the role of the CHRNB2 gene in smoking cessation. Smokers who carry the minor allele of rs2072661 had lower abstinence rates in two independent trials; however, the function of this CHRNB2 variant is unknown (Conti et al. 2008; Perkins et al. 2009). Human genetic studies examining the ChAT gene have also reported initial associations with smoking cessation (Heitjan et al. 2008; Ray et al. 2010). The function of the SNPs in ChAT is unknown and further evidence of replication is important. There is no replicated evidence yet supporting a role of CHRNA6-CHRNB3, CHRNA4, and CHNRA7 genes with smoking cessation as yet.
