Diabetes. 2013 Oct 15.
Lourenço BH, Qi L, Willett WC, Cardoso MA; for the ACTION Study Team.
Public Health Nutrition Program, School of Public Health, University of São Paulo, São Paulo, Brazil.
Previous evidence suggests that variants in the fat mass and obesity-associated gene (FTO) affect adiposity in an age-dependent fashion in children, and nutritional factors may modify genotype effects. We assessed the effect of FTO rs9939609 on BMI and BMI-for-age Z score changes during childhood in a population-based longitudinal study in the Brazilian Amazon and investigated whether these effects were modified by vitamin D status, an important nutritional factor related to adiposity. At baseline, 1088 children aged <10 years had complete genotypic and anthropometric data; 796 were followed up over a median 4.6 years. Baseline vitamin D insufficiency was defined as <75 nmol/L.
We observed a 0.07 kg/m2/y increase in BMI and a 0.03 Z/y increase in BMI-for-age Z score per rs9939609 risk allele over follow-up (P = 0.01).
Vitamin D status significantly modified FTO effects (P for interaction = 0.02). The rs9939609 risk allele was associated with a 0.05 Z/y increase in BMI-for-age Z score among vitamin D insufficient children (P = 0.003), while no significant genetic effects were observed among vitamin D sufficient children. Our data suggest that FTO rs9939609 affects child weight gain, and genotype effects are more pronounced among children with insufficient vitamin D levels.