PCSK1 and obesity due to melanocortin 4 receptor deficiency: One additional medication, setmelanotide [99], is FDA-approved for youth aged 6 and older with one of four rare genetic conditions leading to severe early-onset obesity: pro-opiomelanocortin (POMC) deficiency, proprotein subtilisin/kexin type 1 (PCSK1) deficiency, leptin receptor (LEPR) deficiency, and Bardet–Biedl Syndrome (BBS).