Hyperphagia, commonly observed in individuals with PWS, is associated with a defect in the hypothalamic arcuate nucleus, which is the major action site of multiple complex interactions between neuropeptide Y (NPY), agouti-related peptide (AgRP), proopiomelanocortin (POMC), and leptin, regulating the food intake and body weight (85, 86). This evidence concerns the gene NPY and Polyphagia.