MC4R and obesity due to melanocortin 4 receptor deficiency: Genes encoding leptin (LEP), leptin receptor (LEPR), melanocortin 4 receptor (MC4R), proprotein convertase subtilisin/kexin type 1 (PCSK1), proopiomelanocortin (POMC), kinase suppressor of ras 2 (KSR2), adenylate cyclase 3 (ADCY3), and others contribute to the development and progression of obesity [7].