Prader-Willi Syndrome (PWS) is a non-inherited genetic disorder that occurs in approximately one out of every 15,000 births. PWS affects males and females with equal frequency and affects all races and ethnicities. It is caused by a group of inactive genes on the 15th chromosome. PWS is a spectrum disorder and symptoms vary in severity and occurrence among individuals.

Symptoms of PWS are believed to be caused by dysfunctions of a portion of the brain called the Hypothalamus. The Hypothalamus is a small Endocrine Organ at the base of the brain that plays a crucial role in many bodily functions, including hunger and satiety, temperature and pain regulation, fluid balance, puberty, emotions, small hands and feet, Scoliosis, sleep disturbances with excessive daytime sleepiness, and fertility. Behavior difficulties may include obsessive-compulsive symptoms, picking at the skin, and controlling emotions.
 

In the first stage, infants with PWS are hypotonic or "floppy" with very low muscle tone. Weak cry and a poor suck reflex are typical. Babies with PWS usually are unable to breastfeed and frequently require tube feeding. "Failure to thrice" becomes an issue if not closely monitored. As these children grow older, strength and muscle tone generally improve. Motor milestones are achieved, but are usually delayed.
 

Between the ages of 2 and 6 an insatiable hunger begins regardless of food intake. Individuals with PWS lack normal hunger and satiety cues. They are not able to control their food intake and will over eat if not closely supervised. Due to the hunger and obsession with food, those with PWS will go to extreme measures to find food. Another underlying problem is a slower metabolism which causes individuals with the disorder to not burn calories sufficiently. Left untreated, the combination of these problems will lead to morbid obesity and other complications.