The impact of genetic variation in DRD2 and SLC6A3 on smoking cessation in a cohort of participants 1 year after enrollment in a lung cancer screening study

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Abstract
Smoking cessation strategies continue to have disappointing results. By determining the interindividual genetic differences that influence smoking behaviors, we may be able to develop tailored strategies that increase the likelihood of successful cessation. This study attempts to determine genetic influences on the relationship between the dopamine pathway and smoking cessation by examining associations with a variable number tandem repeat variation in SLC6A3 and the DRD2 variants TaqIA (A2 vs. A1) , TaqIB (B2 vs. B1) , C957T (C vs. T) , and −141C Ins/Del (C vs. Del) . Baseline smokers in the Pittsburgh Lung Screening Study who provided information on smoking status 1 year later were evaluated. We frequency‐matched those who were not abstinent at 1 year to those who were abstinent at 1 year by gender, decade of age, and time of enrollment (3‐month intervals) in a 3:1 ratio (N = 881). Logistic regression was used to identify the effect of genotype on abstinence at 1 year. In a model containing the matching variables and other genotypes, DRD2 TaqIA was significantly associated with being abstinent at 1 year (P = 0.01). Compared to participants who were homozygous for the TaqIA major allele (A2A2 ), participants who carried at least one minor allele (A1 ) were less likely to quit (Odds Ratio: 0.47, 95% CI: 0.24–0.94). The other dopamine receptor genotypes and the SLC6A3 genotype were not associated with smoking status at 1 year. The association between DRD2 TaqIA and smoking cessation supports the hypothesis that genetic variation in the dopamine pathway influences smoking cessation.