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Aims: There is a growing body of data suggesting the gene-environment interaction in the characterization of personality traits, but variation in ordinary parental rearing among environmental factors has not been focused yet. We examined the effects of the interaction between the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism and parental rearing on personality traits. Methods: Subjects were 710 Japanese healthy volunteers. Perceived parental rearing was assessed by the Parental Bonding Instrument (PBI), which consists of the care and protection factors. Personality assessment was performed by the Temperament and Character Inventory (TCI), which has 7 dimensions, i.e., novelty seeking, harm avoidance, reward dependence, persistence, self-directedness, cooperativeness, and self-transcendence. The BDNF Val66Met polymorphism was detected by the PCR-RFLP method. Results: Parental rearing has significant main effects on all TCI dimensions except novelty seeking, while no significant main effects of the BDNF genotype on the TCI scores were found. The interaction between the BDNF genotype and maternal care of the PBI had significant effects on harm avoidance and self-directedness of the TCI. Post-hoc analyses showed that decreased maternal care was correlated with increased harm avoidance and decreased self-directedness in most of the genotype groups, and for both personality traits the correlation was highest in the Met/Met genotype and lowest in the Val/Val genotype and that for the Val/Met genotype was in between the two values. Conclusion: The present study suggests that the BDNF Val66Met polymorphism moderates the effects of parenting rearing, especially maternal care, on harm avoidance and self-directedness in healthy subjects. [ABSTRACT FROM AUTHOR]

Introduction: Dopamine and norepinephrine are implicated in the characterization of personality traits. Dopamine-β-hydroxylase (DBH) is the enzyme responsible for conversion of dopamine to norepinephrine. Previous studies have shown that the -1021C/T polymorphism of the DBH gene promoter influences plasma DBH activity. Few studies investigated the association between this polymorphism and personality traits. Aim: To examine the association between the -1021C/T DBH polymorphism and personality traits in healthy volunteers. Methods: The participants were 627 Japanese unrelated volunteers. The subjects with present psychiatric disorders or past history of psychiatric disorders according to the DSM-IV were excluded. The DBH genotypes were identified by a PCR-RFLP method, and personality traits were assessed by the Temperament and Character Inventory (TCI). The study protocol was approved by the Ethics Committee of Yamagata University School of Medicine, and all subjects provided written informed consent to participate. Results: In the two-factor analysis of covariance with the DBH genotype and sex as factors and with age as a covariate, there was no main effect of the DBH genotype on any TCI score, while the interaction between the factors was significant in harm avoidance. In the post-hoc analysis, the group with the T allele predictive of lower DBH activity had higher scores of harm avoidance than that without the T allele in females (p=0.006), but not in males. Conclusion: The present study suggests that the -1021C/T DBH polymorphism affects the personality trait of harm avoidance in healthy females. [ABSTRACT FROM AUTHOR]