Previous pharmacogenetic studies of smoking cessation, focusing on bupropion treatment, also identified polymorphisms in CHRNB2 associated with treatment response. In each of these studies, there is evidence to suggest that response to treatment in the placebo group may also be associated with CHRNB2, albeit to a lesser degree (Conti et al, 2008; Heitjan et al, 2008; Perkins et al, 2009). In our study, we detect a similar, nominal association in our placebo group with a CHRNB2 SNP (rs2072659, p=0.003, q=0.38). Thus, the genetic association of CHRNB2 with response to varenicline might be explained in part by an increased likelihood to quit, regardless of treatment.
