Relationship between rs9939609 FTO polymorphism with waist circumference and body fat is moderated by ponderal index at birth in youth

Objective The goal of this study was to analyze whether the relationship between the rs9939609 polymorphism of the fat mass and obesity‐associated gene (FTO) with nutritional status is moderated by the ponderal index (PI) at birth in children and adolescents. Methods A cross‐sectional study evaluated 382 schoolchildren aged 6–17 years. Anthropometric variables such as waist circumference (WC), body mass index (BMI) and body fat percentage (BF%) were used to assess nutritional status. Weight and height at birth were used for the PI calculation, which was divided into tertiles (lower, middle and upper). To compare the continuous variables between genotypes of the rs9939609 polymorphism, a recessive model (TT/AT vs. AA) and covariance analysis (ANCOVA) were used. Results The AA genotype of the rs9939609 polymorphism was associated with higher WC in schoolchildren born with lower PI (β = 4.40; p = .048). However, for BF%, the genotype association was found in the upper PI tertile (β = 7.35; p = .040). Conclusion The relationship between WC and BF% with rs9939609 polymorphism (FTO) seems to be moderated by PI at birth. This is an important insight, since the data for intrauterine growth, genetic factors and the presence of obesity in children and adolescents are still contradictory.