Significant decrease of NPY and tendency to decreased NPY mRNA expression in all obese subjects, including PWS, but consistent with literature on inhibition on NPY in obesity.No significant difference in AGRP and NPY staining, or NPY mRNA expression, between PWS and obese adults without PWS.NPY/AGRP neurons show appropriate functioning. The gene discussed is NPY; the disease is obesity due to melanocortin 4 receptor deficiency.