FTO rs9939609: T>A Variant and Physical Inactivity as Important Risk Factors for Class III Obesity: A Cross-Sectional Study

Background: The prevalence of obesity has been increasing worldwide. It has been reported that physiological and environmental factors such as diet, culture, physical activity, and genetics are the principal factors related to obesity. The fat mass and obesity-associated (FTO) gen variant (rs9939609: T>A) has been associated with class III obesity. The A variant has been correlated with anthropometric and metabolic alterations. Therefore, the purpose of this study was to analyze the association of the FTO rs9939609: T>A variant and environmental factors with clinical, anthropometric, and biochemical variables in subjects with class III obesity.

Results: The A variant frequency was higher in the class III obesity group compared with the normal weight group (44% vs. 25%, p < 0.001). Subjects with the AA genotype had a higher body mass index (BMI) than those with the AT genotype (35.46 kg/m² (31-39.8) vs. 26.91 kg/m² (23.7-30), p = 0.005). Women with the AA genotype showed higher waist circumferences than the AT group (101.07 cm (90.9-111.1) vs. 85.45 cm (77-93.8) p = 0.047). The FTO A variant increases the risk by 3.54 times and physical inactivity increases the risk by 6.37 times for class III obesity.

Conclusions: Our results suggest that among the studied variables, those most related to class III obesity were the FTO risk genotype (A allele) and physical inactivity.