There is evidence to support the role of the β2 subunit in smoking cessation in humans. rs2072661 in the CHRNB2 gene has been associated with smoking cessation success and time to relapse in a nAChR systems-based analysis of data from a bupropion placebo-controlled randomized clinical trial (Conti et al. 2008). Smokers who carry the minor allele had lower abstinence rates and more severe withdrawal severity than those heterozygous for wild-type allele (Conti et al. 2008). Perkins et al. (2009) examined the association of this polymorphism with ability to quit during a week of nicotine versus placebo patch use. Consistent with the prior study (Conti et al. 2008), smokers who carried the minor allele were less successful maintaining abstinence on NRT versus placebo compared to those with the wild-type genotype (Perkins et al. 2009). However, the function of this specific variant is unknown. More recently, King et al. (2011) reported CHRNB2 SNPs rs3811450 and rs4262952 were associated with abstinence in smokers treated with varenicline. There is also evidence that CHRNB2 interacts with CHRNA4 in affecting nicotine dependence (Li et al. 2008). Thus, future studies of smoking cessation that are sufficiently powered to detect gene–gene interactions could extend this finding.
