Supplementary Material for: Association of Genetic Polymorphisms for Glutathione Peroxidase Genes with Obesity in Spanish Children

Background/Aims: Altered expression and activity of the antioxidant enzymes glutathione peroxidases (GPXs) have been observed in obesity in human and animal studies. We aimed to study 59 single nucleotide polymorphisms (SNPs) for GPX1-7 genes and to characterize their association with prepubertal childhood obesity and its associated biomarkers. Methods: This case-control study included 193 obese and 191 normal-weight prepubertal Spanish children, in whom anthropometry, biochemical parameters, adipokines, antioxidant enzyme erythrocyte activities and biomarkers of oxidative stress, inflammation and cardiovascular risk were measured. The genotype analysis was performed in the Illumina platform. PLINK and SPSS were used for statistical analyses. Results: We found SNPs rs757228 and rs8103188 (GPX4) to be negatively associated and rs445870 (GPX5) and rs406113 (GPX6) to be positively associated with obesity in children. The variant rs2074451 (GPX4) increased GPX activity in erythrocytes. Although we did not find significant differences in erythrocyte GPX activity between obese and normal-weight children, GPX activity was found to be positively and significantly correlated with blood pressure, adipocyte fatty acid-binding protein and high-sensitivity C-reactive protein. Conclusions: The GPX variants rs757228, rs8103188, rs445870 and rs406113 were associated with prepubertal childhood obesity. However, erythrocyte GPX activity was not altered in obese prepubertal Spanish children.