The large smoking cessation trial offers a distinct, complementary test of the association between haplotype status and cessation. In this study, the genetic associations with smoking cessation are manifested in the placebo group, which is consistent with the results obtained in the ARIC “natural history” sample. In contrast, these genetic variants do not predict abstinence across active treatment conditions, and this reduced genetic effect in the context of active pharmacological treatments suggests that cessation treatments differ in effectiveness across the haplotypes and mitigate the genetic risks for cessation difficulty. Pharmacological cessation treatment significantly increased the likelihood of abstinence in individuals with the high-risk haplotype H3, but exerted little effect in individuals with the low-risk haplotype H1.
