Prospective association of dopamine-related polymorphisms with smoking cessation in general care

Aims: Genetic contributions to nicotine dependence have been demonstrated repeatedly, but the relevance of individual polymorphisms for smoking cessation remains controversial. Materials & methods: We examined genotypes at two dopamine-related loci, DRD2/ANKK1 (rs1800497) and DBH (rs77905), in 577 heavy smokers participating in a prospective study of smoking cessation in general care in Germany. Results: Smoking status after 1 year was significantly associated with DRD2/ANKK1, odds of abstinence being 4.4-fold (95% CI: 1.5-12.9) increased in TT- versus CC-homozygous subjects (p = 0.008). No effect was observed for the DBH genotype. The smoking cessation drug bupropion appeared to be particularly effective in CC-homozygotes (among CC subjects there was a 28% higher cessation probability among those taking buproprion; among T carrier subjects there was an increase only by 12%). Conclusion: The large effects observed for DRD2/ANKK1 might be related to our study design, in which individual therapy was decided by the physician. Further studies are needed to clarify the genetic effects of DRD2/ANKK1 especially in 'real-life' settings outside clinical trials.