Purpose: The decline of physical activity in children is considered an important determinant to explain the rising rates of obesity. However, this risk may be augmented in children who are genetically susceptible to increased weight gain. We hypothesized that a sedentary lifestyle and moderate activity will interact with genetic loci, resulting in differential effects in relation to obesity risk.
Methods: We recruited 643 European children born to participants in the New Zealand-based Screening for Pregnancy Endpoints (SCOPE) study. Seventy gene variants were evaluated by the Sequenom assay. Interaction analyses were performed between the genetic variants and the activity type derived from actigraphy, in relation to percentage body fat.
Results: We found a statistically significant association between increased proportions of sedentary activity with increased percentage body fat scores (P = .012). The OLFM4-9568856 (P = .01) and GNPDA2-rs10938397 (P = .044) gene variants showed genotype differences with proportions of sedentary activity. Similarly, the OLFM4-9568856 (P = .021), CLOCK-rs4864548 (P = .029), and LEPR-1045895 (P = .047) showed genotype differences with proportions of moderate activity. We found evidence for unadjusted gene-by-activity interactions of SPACA3/SPRASA-rs16967845, PFKP-rs6602024, and SH2B1-rs7498665 on percentage body fat scores.
Conclusions: These findings indicate a differential effect of physical activity in relation to obesity risk, suggesting that children genetically predisposed to increased weight gain may benefit from higher levels of moderate activity.
Keywords: BMI z scores; childhood obesity; genetics; moderate activity; percentage body fat; sedentary behavior.