Abstract:

The influencing factors and underlying mechanisms of aggressive behavior are important fundamental issues in research on human aggression. With the advancement of molecular genetics, the research on the mechanisms of aggression has reached molecular level in recent years. Recent studies using candidate gene strategy have demonstrated that the COMT (catechol-O-methyltransferase) gene was significantly associated with human aggression. However, existing research mainly focused on physical aggression, while the genetics mechanism of relational aggression has scarcely been investigated. To our knowledge, only two studies examined the genetic underpinnings of the two specific subtypes of aggression by examining the direct associations between COMT gene Val158Met polymorphism and both physical and relational aggression, but these studies failed to investigate the gene-environment interaction. Recent research has revealed a new functionally single nucleotide polymorphism rs6267 in the COMT gene which also plays an important role in individual’s development, but its possible interaction with environment on aggressive behavior remains unclear. The present study aimed to extend the previous research by examining the association between COMT gene rs6267 polymorphism and both physical and relational aggression among Chinese children and adolescents, with a particular focus on the possible moderating effects of maternal parenting behavior and gender on the association. One thousand two hundred and fifty eight children (male = 649) from 40 classes of 14 primary schools in Jinan City were followed from grade 4 till to grade 7. The subjects’ physical and relational aggression were obtained through peer rating, and the maternal parenting behavior was measured by mother report. DNA was extracted from saliva. In detail, genotype at rs6267 polymorphism in the COMT gene was performed for each participant in real time with MassARRAY RT software version 3.0.0.4 and analyzed using the MassARRAY Typer software version 3.4 (Sequenom). Pearson correlation and hierarchical regression analyses were conducted to examine the effect of rs6267 polymorphism and maternal parenting behavior on adolescent aggression. The main findings of the present study were as follows: Rs6267 polymorphism in the COMT gene significantly interacted with maternal parenting behavior in predicting adolescent physical aggression, but this interaction was observed only among males, such that maternal warmth negatively predicted male adolescent physical aggression among carriers of GG homozygote but not T allele. Similarly, maternal rejection and punishment only positively predicted male adolescent physical aggression among carriers of GG homozygote but not T allele. However, the interaction between rs6267 polymorphism in the COMT gene and maternal parenting behavior on adolescent relational aggression was not significant. The findings of the present study indicate that gene-environment interactions on adolescents’ aggression may vary across physical and relational aggression and across gender, and thereby provide additional support for the dichotomy of these two subtypes of aggression. Besides, by elaborating the moderating effect of maternal parenting behavior and gender, the present study enriches the literature of the relation between COMT gene and aggression.

Key words: COMT gene, physical aggression, relational aggression, gene-environment interaction, parenting behavior