Genomic DNA was extracted and variants in <i>DBC1</i> (rs17060940), <i>SIRT1</i> (rs7895833 and rs1467568), <i>UCP2</i> (rs660339), <i>PPARG</i> (rs1801282) and <i>ADRB2</i> (rs1042713 and rs1042714) genes were genotyped by PCR allelic discrimination using TaqMan<sup>®</sup> assays.<h4>Results</h4>Our findings indicated that <i>SIRT1</i> rs7895833 polymorphism was a risk factor for severe obesity development in the overdominant model. The gene discussed is PPARG; the disease is obesity due to melanocortin 4 receptor deficiency.