Background: Previous research suggests that early life socioeconomic stress and certain genetic polymorphisms may be partly associated with increased adiposity; however, research on both genetic and environmental predictors fail to account for the dramatic increase in obesity over that last several decades. Hypothesis: It was hypothesized that a GxE interaction between DRD2-related SNPs and parental education would predict trunk and total fat mass. This same interaction would also predict total calories from a 24-hour diet recall, which would mediate its effect on trunk and total fat mass. Sample: The current study analyzed genetic and psychosocial data from 697 participants collected for the Family Heart Study, an investigation examining the relationship between psychosocial behaviors and cardiovascular risk factors. Methods: Interactions were assessed between four single nucleotide polymorphisms (SNPs) in the D2 receptor and ANKK1 genes and tertiles of parental education predicting DXA-scan-measured trunk and total body fat mass. A measure of total calories, as assessed by a 24-hour diet recall, was tested as a mediator of this effect. Results: An interaction between mother;;s education and RS1116313 SNP predicted trunk fat (F(4,191)=2.94, p=0.022) and total body fat (F(4, 191)=3.94, p=0.004). The effects were driven by a reduction in trunk and total fat mass among C/C or T/T homozygotes with a high mother;;s education, which was not observed among C/T heterozygotes. Father;;s education was neither an interactive nor a main effect predictor in any models. Interactions predicting total calories were also non-significant, and no support for mediation was found. Post-hoc analyses revealed that leisure activity was also not a mediator. Alternatively, certain dietary components were predicted by the interactions between mother;;s education and RS1124492 and between mother;;s education and RS1800498. Conclusions: Trunk and total body fat composition are predicted by an interaction between mother;;s education and the RS1116313 SNP. This effect does not appear to be mediated by total calories or leisure activity. Other SNPs associated with the D2 receptor interact with mother;;s education to predict dietary components.
