MC4R and Prader-Willi syndrome: Some evidence also suggests chromosome 15q11-13 deletion common to Prader-Willi syndrome (PWS) may also impact the MC4R pathway through deletion of MAGEL2 or SNORD116, which alter leptin receptor signaling and expression of serotonin 2 C receptors involved in activation of POMC neurons, respectively [11, 38–42].