It is known that the coexistence of other genetic variants related to energy metabolism such as melanocortin receptor (MC4R), obesity protein and associated fat mass (FTO), pro-opiomelanocortin (POMC), interleukin 6 (IL6), uncoupling protein 1 (UCP1), perilipine 5 (PLIN 5) agouti-related peptide (AGRP), leptin (LEP) may increase the influence of Pro12Ala on body composition. The gene discussed is POMC; the disease is obesity due to melanocortin 4 receptor deficiency.