Does the FTO Gene Interact with the Socio‐Economic Status on the Obesity Development Among Young European Children? Results from the IDEFICS Study

Various twin studies revealed that the influence of genetic factors on psychological diseases or behavior is more expressed in socio‐economically advantaged environments. Other studies predominantly show an inverse relation between socio‐economic status (SES) and childhood obesity in western developed countries. The aim of this study is to investigate whether the FTO gene
interacts with the socio‐economic status (SES) on childhood obesity in a subsample of the IDEFICS cohort (N=4406). A structural equation model (SEM) is applied with the latent constructs obesity,
dietary habits, physical activity and fitness habits, and parental SES to estimate the main effects of the latter three variables and a FTO polymorphism on obesity. Further, a multiple group SEM is used
to explore whether an interaction effect between the single nucleotide polymorphism rs9939609 within the FTO gene and SES exists. Overall model fit was inconsistent (RMSEA=0.05; CFI=0.79).
Significant main effects are shown for SES (standardized βs=‐0.057), the FTO homozygous risk genotype AA (βs=0.177) and physical activity and fitness habits (βs=‐0.113). The explained variance of obesity is about 9%. The multiple group SEM shows that SES and FTO interact in their effect on childhood obesity (Δχ2=7.3, df=2, p=0.03) insofar as children carrying the protective TT genotype are more susceptible to a favorable social environment.