Association between the FTO gene polymorphism and obesity in Brazilian adolescents from the Northeast region

Abstract

Objective: To investigate the association between the FTO gene polymorphism with obesity in Brazilian adolescents from the Northeast region. Method: This was a case–control study with adolescents aged 18 to 19 years. The case group consisted of 378 obese individuals and the control group of 378 non-obese individuals. Obesity was measured by percentage of body fat using the air displacement plethysmography technique. The study variables included data on socioeconomics, demographics, lifestyle, physical activity, waist circumference, waist-to-height ratio, and body mass index. To identify the rs9939609 polymorphism of the FTO gene, blood samples were obtained for genomic DNA extraction by the real-time PCR (Polymerase Chain Reaction) technique. Categorical variables were compared between the groups by the chi-squared test. The normality of the anthropometric measurements body mass index, waist circumference, waist-to-height ratio, and percentage of body fat was evaluated by the Shapiro–Wilk test. Comparison of the anthropometric measurements, stratified by the polymorphism genotypes, was performed by the Kruskal–Wallis test. The Hardy–Weinberg equilibrium was calculated. The significance level was set at 5%. Results: The variables gender, age, and physical activity showed significant differences between the groups (p < 0.001). The samples of obese and non-obese adolescents were in Hardy–Weinberg equilibrium (p = 0.0515). There was no significant difference between the genotypic (p = 0.719) and allelic frequencies (p = 0.812) regarding the case and control groups. When comparing the anthropometric measurements according to the genotypes (AA, AT, and TT), no significant difference was observed for body mass index (p = 0.337), waist circumference (p = 0.3473), percentage of body fat (p = 0.7096), and waist-to-height ratio (p = 0.2584). Conclusion: The excess adiposity of the study adolescents was not influenced by their genotype.