Maternal prenatal smoking and offspring emotional problems: No moderating effect of maternal or child 5‐HTTLPR genotype

Abstract

In a recent paper, Cents and others (2012) demonstrated a novel interaction effect of a polymorphism in the serotonin transporter gene (5-HTTLPR) and maternal prenatal smoking on offspring emotional (internalizing) problems at age 3 in a sample of 1,529 Dutch mother-child dyads. The 5-HTTLPR polymorphism has previously been shown to moderate effects of stressful life-events and childhood maltreatment on depression (Karg and others, 2011). Cents and others (2012) extended those findings to the period of fetal life using maternal prenatal smoking as the environmental risk factor, and offspring emotional problems at age 3 as the outcome measure. Cents and others (2012) did not find a significant main effect of the 5- HTTLPR genotype or maternal prenatal smoking on offspring emotional problems, but detected an interaction effect. Having the short allele of the 5-HTTLPR polymorphism in combination with maternal smoking during pregnancy was associated with increased emotional problems at age 3 as rated by the mother. A similar interaction was observed for maternal 5-HTTLPR genotype and this effect was independent of the child’s genotype, suggesting that maternal serotonin levels influence fetal development. The interactions remained significant after correction for maternal educational level, maternal psychopathology, and age and sex of the child. Maternal rater bias was controlled for by alternatively using paternal ratings of offspring emotional problems which showed comparable results. Moreover, when Cents and others (2012) repeated the analyses using paternal prenatal smoking as a predictor instead of maternal prenatal smoking, no interaction with 5-HTTLPR was observed, providing additional support for a direct effect of prenatal tobacco exposure as opposed to confounding effects.