Association study of monoamine oxidase and catechol-O-methyltransferase genes with smoking behavior.

OBJECTIVE: The genes of catalytic enzymes of dopamine, including monoamine oxidase (MAOA and MAOB) and catechol-O-methyltransferase (COMT), have been major candidates for genes that affect smoking behavior. In this study, we investigated the relationship between smoking behavior and four polymorphisms of these genes, the MAOA variable number tandem repeat polymorphism, the MAOA 1460 T/C polymorphism, the MAOB intron 13 G/A polymorphism, and the COMT Val158Met polymorphism. The association between the MAOB polymorphism and personality traits was also explored.

PARTICIPANTS AND METHODS: The polymorphisms were genotyped in 451 healthy Japanese volunteers. Data on smoking habits were obtained from structured interviews. In addition to testing the association between each polymorphism and smoking status, epistatic and additive effects between two polymorphisms were also investigated.

RESULTS: A significant association was observed between the COMT Val158Met polymorphism and smoking status. Male participants with the Val/Val genotype had a significantly higher risk of heavy smoking compared with those with other genotypes, although no significant association was observed in female participants. No evidence was obtained for an association between the MAO genes and smoking behavior, including epistatic or additive effects. No significant association was observed between the MAOB polymorphism and personality traits.

CONCLUSION: This study may suggest a role of the COMT Val158Met polymorphism in smoking behavior in Japanese individuals.