<i>COMT</i> Val ¹⁵⁸ Met polymorphism protects the impact of a mother's history of childhood trauma on emotional and behavioural problems in preschool children

Childhood trauma has a well-established negative impact on mental health outcomes across the lifespan. Cumulative evidence suggests an intergenerational transmission of trauma to descendants. In this way, considering the child's COMT Val¹⁵⁸Met (rs4680: G > A) variant, the study aims to investigate the interactive effect of maternal childhood trauma on the emotional/behavioural problems of their offspring in preschoolers age (4-5 and 11 years old) from a population-based dyad of pregnant adolescent women. The behaviour problems of 310 children were assessed using the Child Behaviour Checklist (CBCL) instrument, and maternal trauma was assessed with the Child Trauma Questionnaire (CTQ) between the 20 to 22° gestational weeks. Maternal childhood trauma increases the risk for all emotional/behavioural problems in the offspring, and no direct association between the child's Val¹⁵⁸Met genotypes with emotional/behavioural problems. Interestingly, in moderation analysis adjusted by sex, age and skin colour, children of mothers exposed to childhood trauma, carrying the Val/Met genotype, are less likely to develop externalising (p = .020) and total problems (p = .041) when compared to homozygous (Val/Val and Met/Met). Thus, our findings reinforce evidence on the intergenerational impact of maternal trauma on emotional/behavioural problems and demonstrate that this risk is influenced by the genetic background of the individual, varying according to the functional COMT genotype, which confers a protective profile for the development of externalising and total problems.