No association between catechol-O-methyltransferase (COMT) genotype and attention deficit hyperactivity disorder (ADHD) in Japanese children

Abstract Objective: This study ascertained the association between attention deficit/hyperactivity disorder (ADHD) in Japanese children and a polymorphism of catechol- O -methyltransferase ( COMT ), a dopamine-control gene. The secondary aim of the study was the evaluation of a putative association between methylphenidate (MPH) effect/adverse effects and the COMT genotype. Methods: To ascertain the distribution of the Val158Met variant of COMT , 50 children meeting ADHD inclusion criteria were compared with 32 healthy children. Clinical improvement and the occurrence of adverse effects were measured before and 3 months after MPH administration in children with ADHD, and analyzed for genotype association. Wechsler Intelligence Scale for Children-Third Edition (WISC-III), age, MPH dose were included as co-variables. Results: The occurrence of the COMT Val/Val genotype was significantly higher in children with ADHD ( χ 2 (1) = 7.13, p COMT genotype. Furthermore, no significant difference in MPH effect/adverse effects was observed in association with the COMT genotype in the ADHD group. Conclusions: These results showed a lack of association between the COMT Val/Val genotype and ADHD in Japan.