Prader-Willi Syndrome (PWS) is a genetic disorder that occurs in approximately one in every 12,000 to 15,000 births. The disorder develops in two stages. Infants have muscle weakness, feeding difficulties and poor growth. During childhood, this is replaced by an insatiable appetite, slow metabolism, behavioral problems, and learning difficulties. Severe, life-threatening obesity results if food intake is not strictly controlled.
PWS is caused by a gene missing on chromosome 15. Most individuals with PWS are missing genetic material on part of the father's chromosome. Others with this condition have two copies of the mother's chromosome 15. PWS is the most common genetically-identified cause of life-threatening obesity in humans.
Currently there is no cure for PWS, and most research to date has been targeted towards treating specific symptoms. For many individuals affected by the disorder, the elimination of some of the most difficult aspects of the syndrome, such as the insatiable appetite and obesity, would represent a significant improvement in quality of life and the ability to live independently.