Association of DRD4 and COMT polymorphisms with anger and forgiveness traits in healthy volunteers

Although the biological basis of trait anger, anger expression, and forgiveness are not well understood, there has been growing evidence that anger-related dispositions are heritable and associated with genetic polymorphisms. The purpose of the present study was to investigate the possible relationship between anger and forgiveness traits and the dopamine receptor D4 (DRD4) and catechol-O-methyltransferase (COMT) Val158 Met polymorphisms in healthy Korean subjects. Three hundred and thirty-five healthy college students were recruited, and the 308 participants with a complete data set (184 males, 124 females) were included in the data analysis. DNA of the subjects was isolated from whole blood cells, and DRD4 variable number of tandem repeats and COMT Val158 Met polymorphisms were genotyped using polymerase chain reaction. Participants performed the State-Trait Anger Expression Inventory and Trait Forgivingness Scale measuring anger and forgiveness traits. The DRD4 2-repeat (2R) allele group had significantly lower anger in tendency and higher forgiveness traits than the 4R allele group in males. Our results provide evidence that the 2R allele of DRD4 in a Korean sample might have a different function from the 4R allele and a gender-specific role on anger-related traits. The COMT Val158 Met polymorphism had no significant relationship with anger and forgiveness traits. These findings suggest a possible relationship between anger expression styles and forgiveness traits and dopaminergic dysfunction.