TCF7L2 and obesity due to melanocortin 4 receptor deficiency: To further assess whether the presence of specific SNPs with a high frequency in the Mexican population that have been associated with obesity and IR could explain the metabolic phenotype, particularly the serum insulin levels and HOMA-IR, we analyzed the SNPs for ABCA1, FTO, GFOD2, PPARγ, and TCF7L2 in subjects with IR or MetS.