Several genes, such as pro-opiomelanocortin (POMC), leptin receptor (LEPR), leptin (LEP), proconvertase 1 prohormone convertase 1 (PC1), and melanocortin 4 receptor (MC4R), have been confirmed as harboring mutations that are casual to the onset of monogenic obesity, together accounting for 3–5% of non-syndromic cases [8], although there is evidence that genetic variants in LEP, LEPR, and MC4R explain 30% of severe obesity in children from consanguineous populations [9]. The gene discussed is LEP; the disease is obesity due to melanocortin 4 receptor deficiency.