No association between CYP2D6 polymorphisms and personality trait in Japanese

What is already known about this subject • CYP2D6 mediates, to some extent, the synthesis of the neurotransmitters, serotonin and dopamine in the brain. A positive relationship between CYP2D6 activity and personality has been suggested, while other studies have failed to find a relationship. • Therefore, because of these inconsistent findings, the association between CYP2D6 polymorphism and interindividual variability in personality has not yet been resolved. What this study adds • The detailed genotypes for CYP2D6 were identified using DNA tip in a large number of Japanese subjects. However there were no correlations between scores of personality and CYP2D6 genotypes. • This study demonstrated that there was no significant association between CYP2D6 activity and personality trait in the Japanese population. Aims The polymorphic enzyme CYP2D6 is expressed not only in liver but also in brain at low concentrations. CYP2D6 mediates, to some extent, the synthesis of the neurotransmitters, serotonin and dopamine. We investigated a possible association between the genetic polymorphism of CYP2D6 and individual personality trait. Methods Mentally and physically healthy volunteers were recruited ( n = 342). Temperament and Character Inventory (TCI) and CYP2D6 genotyping were performed in all subjects. We detected mutated alleles which were identified using the Amplichip CYP450 DNA chip. Results The number of phenotypes, assumed by genotype for ultrarapid metabolizers (UM), extensive metabolizers (EM), intermediate metabolizers (IM) and poor metabolizers (PM) were 4 (1.1%), 262 (76.6%), 75 (21.9%) and 1 (0.3%), respectively. There were no differences in scores for novelty seeking, harm avoidance, reward dependence or persistence among the CYP2D6 phenotypes. The number of mutated alleles for CYP2D6 did not differ for scores of novelty seeking, harm avoidance, reward dependence or persistence. In subitem analyses, only RD3 (attachment) had a significant difference both in the CYP2D6 phenotype ( P < 0.05) and genotype ( P < 0.05). Conclusions This study did not demonstrate a significant association between CYP2D6 activity and personality trait because of the small interindividual variability in CYP2D6 activity within the Japanese population.