Fewer studies have examined associations of CYP2A6 with smoking cessation. Retrospective studies have demonstrated that individuals with the low activity alleles of CYP2A6 are twice as likely to quit smoking (Gu et al., 2000) and are less likely to experience severe withdrawal after a quit attempt (Kubota et al., 2006), compared to smokers with the wild-type genotype. As discussed in more detail below, further studies have begun to explore the relationship of inherited variation in nicotine-metabolizing enzymes in clinical trials of pharmacotherapies for nicotine dependence.
