MC4R and obesity due to melanocortin 4 receptor deficiency: For example, setmelanotide, a melanocortin-4 receptor agonist, has shown efficacy in patients with impaired leptin-melanocortin signaling—a defect that may occur in patients with non-syndromic obesity (e.g., POMC deficiency) as well as in those with additional features (e.g., Bardet-Biedl syndrome) [16, 17].