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. Also, mild to moderate intellectual impairment and behavioural problems are typical. Often, the forehead is narrow, hands and feet are small, height is short, skin is light in colour, and most of the affected are unable to have children.