Leptin is a 167-amino acid product produced by the obesity gene and is primarily secreted by adipose tissue as an anorexigenic hormone that transmits satiety signals to the central nervous system.33 Leptin reduces food intake by upregulating anorexigenic signals such as POMC and MC4R and downregulating orexigenic signals such as NPY and AgRP34 (Figure 5). Here, LEP is linked to obesity due to melanocortin 4 receptor deficiency.