MC4R and obesity due to melanocortin 4 receptor deficiency: The MC4R is the melanocortin receptor subtype responsible for satiety signaling mediated by α-melanocyte stimulating hormone (α-MSH), which is released from proopiomelanocortin (POMC)-containing neurons in the arcuate nucleus, and deficiency in the MC4R results in hyperphasia and blunted thermogenic responses to increased dietary fat, leading to severe obesity [3, 6, 22].