Prader-Willi Syndrome or PWS, is a genetic condition that affects children. It is the most common genetic cause of life-threatening obesity. The exact cause is quite complex, but in simple terms, it is an abnormality in the 15th chromosome that causes the disease.
Children with PWS usually have very poor muscle tone. In addition to this, they have incomplete sexual development, short stature (which can be dealt with with growth hormone), and a chronic feeling of insatiable hunger. They also suffer from learning disabilities and motor skills problems.
There is no cure for PWS, but children with the disease can grow up to be adults.