About Prader-Willi Syndrome (PWS)

What is PWS?

The term PWS refers to a genetic disorder that affects many parts of the body. Genetic testing can successfully diagnose nearly all infants with PWS.1

The syndrome usually results from deletions or partial deletions on chromosome 15 that affect the regulation of gene expression, or how genes turn on and off. Andrea Prader and Heinrich Willi first described the syndrome in the 1950s.2

One of the main symptoms of PWS is the inability to control eating. In fact, PWS is the leading genetic cause of life-threatening obesity. Other symptoms include low muscle tone and poor feeding as an infant, delays in intellectual development, and difficulty controlling emotions.

There is no cure for PWS, but people with the disorder can benefit from a variety of treatments to improve their symptoms. These treatments depend on the individual's needs, but they often include strict dietary supervision, physical therapy, behavioral therapy, and treatment with growth hormone, among others. As adults, people with PWS usually do best in special group homes for people with this disorder. Some can work in sheltered environments.

Scientists do not know what increases the risk for Prader-Willi syndrome. The genetic error that leads to Prader-Willi syndrome occurs randomly, usually very early in fetal development. The syndrome is usually not hereditary.3


  1. Cassidy, S. B., Schwartz, S., Miller, J. L., & Driscoll, D. J. (2011). Prader-Willi syndrome. Genetics in Medicine, 14, 10-26.
  2. Prader, A., Labhart, A., & Willi, H. (1956). [A syndrome characterized by obesity, short stature, cryptorchidism, and oligophrenia following a myotonia-like condition in infancy]. Schweizerische Medizinische Wochenschrift, 86, 1260.
  3. McCandless, S. E.; Committee on Genetics. (2010). Clinical report-health supervision for children with Prader-Willi syndrome. Pediatrics, 127, 195-204.
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