Influence of physical activity on the association between the FTO variant rs9939609 and adiposity in young adults

Objectives To investigate in a population sample of Portuguese young adults the association of the FTO variant rs9939609 with obesity, BMI, and body-fat and interaction with physical activity (PA) on obesity-susceptibility. Methods SNP rs9939609 A/T was genotyped in 550 subjects (231 males and 319 females; 18–36 years old; mean age 21 years old) by TaqMan assay. PA was assessed with a validated self-reported questionnaire of IPAQ. Results We replicated the association of rs9939609-A risk allele with BMI (P = 0.04) and fat-mass (P = 0.031), and with overweight (including obesity) under a recessive model (P = 0.034). Stratified analyses showed (i) a significant association with overweight/obesity in inactive individuals (P = 0.02) but not in a group reporting participation in sports (P = 0.97). Spearman's correlation test suggested that the impact of a successive increase in PA was a decrease in the body-fat percentage (r = −0.16; P = 0.0002), which is accentuated for homozygous AA (r = −0.34; P = 0.002), and an increase in BMI (r = 0.14; P = 0.001), with a statistically significant correlation for homozygous TT (r = 0.22; P = 0.002). Conclusions This study reveals interactions between rs9939609 and PA on obesity indices in Portuguese young adults, suggesting a change in the different body components (lean and fat mass) depending on the FTO genotypes. Am. J. Hum. Biol. 27:734–738, 2015. © 2015 Wiley Periodicals, Inc.