MC4R and obesity due to melanocortin 4 receptor deficiency: Briefly, the terms “melanocortin 4 receptor,” “MC4R,” “leptin receptor,” “LEPR,” “proopiomelanocortin,” “POMC,” “Bardet-Biedl syndrome,” “BBS,” and/or “PCSK1” were used in combination with “obesity” with the case reports filter applied to identify studies reporting on patients with hyperphagia in populations of interest.