Gender Differences in the Interaction of Monoamine Oxidase­A and Childhood Adversity as Risk Factors for Conduct Disorder

A sub­sample of 578 males and 720 females, ages 8­17 years from the longitudinal Virginia Twin Study of Adolescent and Behavioral Development (VTSABD) was assessed for MAO­A genotype, exposure to childhood adversity, parental antisocial personality disorder (ASPD), and CD. Mixed models were fitted specifying fixed additive effects on CD of genotypes at the MAO­A locus together with the main effect of adversity, parental ASPD, and the interaction of additive genotypic effects with adversity (Mather, K and Jinks, L, 1982, Biometrical Genetics: The Study of Continuous Variation, 3 rd ed., Chapman and Hall, London). Random residual effects of twin resemblance and repeated measurement were accommodated using the GEE algorithm incorporated in the SAS GENMOD procedure on the simplifying assumption of constant correlation between measures within clusters. In males and females, the analysis revealed significant main effects of increasing childhood adversity as well as maternal, but not paternal ASPD on CD. Marginally significant main effects of genotype and GxE were detected, depending on the precise model adopted for measurement of childhood adversity. These results suggest higher sensitivity to increasing childhood adversity in the presence of high activity MAO­A genotype among females and low activity MAO­A genotype in males.