MC4R and obesity due to melanocortin 4 receptor deficiency: The non-syndromic form consists of monogenic obesity (POMC, NPY, LEP, LEPR, MC3R, MC4R, FTO, PC1, GHSR, etc.)and polygenic obesity (UCP1, UCP2, UCP3, ADRB1, ADRB2, ADRB3, SLC6A14, etc.)[16].