By dopamine release, nicotine reinforces continued use, so genes encoding enzymes responsible for dopamine metabolism are candidates for dependence. rs4680 is a functional polymorphism of COMT (catechol-O-methyl-transferase), determining a high activity Val158 (H, G1497) and low activity Met158 (L, A1497) variant. Though results found have been contradictory, it has been suggested that Val158 carriers are at increased risk to develop addiction. There are differences between the populations, and to our best knowledge no study in the local population has been carried out in this respect. In a case-control study we analyzed rs4680 by PCR-RFLP using Nla III in association with the characteristics of nicotine dependence estimated by NDSS, HSI and FNDS adapted for the local population in 147 smokers and 109 non-smokers. Though genotype associated risk for smoking was not statistically significant (GG vs AA: OR = 1.96, CI95%: 0.5-5.2, p >0.05; GG vs GA+AA: 1.54, CI95%: 0.5-4.3, p > 0.05), the overall scores of dependence and its certain components, namely drive and priority, showed significant differences across the genotypes (p<0.05). In conclusion, COMT appears as a risk modifier involved in the development of nicotine dependence rather than a susceptibility gene for the development of smoking. Further investigations in this respect could have direct practical importance in increasing the efficacy of cessation attempts on an individual basis.
Keywords: nicotine dependence, COMT gene polymorphism.