Catechol-O-methyltransferase Val108/158Met gene and alcoholism in Turkish subjects

Aim: To determine if the functional Val108/158Met polymorphism causes a tendency toward alcohol addiction in Turkish cases. This polymorphism of the catechol-O-methyltransferase (COMT) gene has been associated with many psychiatric disorders, as well as with alcoholism. Materials and methods: The allele and genotype associations of the Val108/158Met polymorphism in 110 Turkish alcoholics and 330 healthy subjects were investigated, constituting our study and control groups, by polymerase chain reaction-restriction fragment length polymorphism. Results: Distribution of the Met/Met genotype was 16.4% to 20.6% and frequency of the Met allele was 36.8% to 39.5% in the study group compared to the control group. The results did not show any signifi cant differences in the genotype distribution and allele frequencies of the polymorphism, neither between the study and the control groups (c^2 = 0.985, P = 0.611 and c^2 = 0.517, P = 0.472) nor between female (c^2 = 0.247, P = 0.884 and c^2 = 0.115, P = 0.735, respectively) and male (c2 = 0.728, P = 0.695 and c^2 = 0.485, P = 0.486, respectively) alcoholics. The power of the study for genotype analysis was set at 79.1%. Conclusion: The present study shows that the polymorphic Met allele of the COMT polymorphism is not associated with alcoholism in Turkish cases; however, due to the lack of statistical power, this research should be evaluated again with an enlarged study group to confirm the possible association between the polymorphism and alcoholism.