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

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.