What is PWS?

PWS was first described by Swiss doctors Andrea Prader, Alexis Labhart, and Heinrich Willi in 1956 based on the clinical characteristics of nine children they examined. The common characteristics defined in the initial report included small hands and feet, abnormal growth and body composition (small stature, very low lean body mass, and early-onset childhood obesity), hypotonia (weak muscles) at birth, insatiable hunger, extreme obesity, and intellectual disability. PWS results from an abnormality of chromosome 15, and definitive diagnosis is based on genetic testing.

The symptoms of Prader‐Willi syndrome are likely due to dysfunction 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 regulating hunger and satiety, body temperature, pain, sleep‐wake balance, fluid balance, emotions, and fertility. Although hypothalamic dysfunction is believed to lead to the symptoms of PWS, it is not yet clear how the genetic abnormality causes hypothalamic dysfunction.