Genetic variants as risk factors for cigarette smoking at an early age and relapse to smoking cessation treatment: A pilot study.

Objectives: Tobacco smoking is a complex and multifactorial disease involving both environmental and genetic factors. In the Mexican mestizo population, single-nucleotide polymorphisms (SNPs) associated with cigarette smoking and a greater degree of nicotine addiction have been identified; however, no possible roles have been explored in regard to the age of onset of smoking or in the success of quitting.

Methods: In this study, 151 Mexican mestizo, who smoke cigarettes, were included. They were grouped according to the age at which they started smoking: those who started smoking before 18 years of age (early smokers, ES) and those who started smoking ≥18 years of age (late smokers, LS). In addition, relapse in smoking was evaluated at the first month after the end of treatment. Genetic association was evaluated characterizing 10 SNPs in 4 genes (CHRNA5, CHRNA3, NRXN1, and HTR2A).

Results: According to the dominant model of genetic inheritance, rs6313 (CT+TT) of the HTR2A gene was associated (p = 0.0201) with cigarette consumption at early ages (OR = 2.68, CI = 1.18-6.07). When the risk of relapse was analyzed one month after the end of treatment, regardless of the age of onset, the T allele (rs6313) of HTR2A appeared to be a risk factor for relapse (OR = 2.92, 95% CI = 1.06-8.11); the T allele was found more frequently in those who relapsed (50.0%) compared with people who maintained abstinence (25.4%) (p = 0.0332).

Conclusions: Our findings suggest that in Mexican mestizos who smoke cigarettes, the presence of the T allele in rs6313 of the HTR2A gene increases the risk for the early onset of cigarette smoking as well as the risk for relapsing one month after completing smoking cessation treatment.