Prader–Willi syndrome (PWS) is a genetic disorder due to loss of function of specific genes. In newborns symptoms include weak muscles, poor feeding, and slow development. Beginning in childhood the person becomes constantly hungry which often leads to obesity and type 2 diabetes. There is also typically mild to moderate intellectual impairment and behavioral problems. Often the forehead is narrow, hands and feet small, height short, skin light in color, and those affected are unable to have children.