Health Topic

Prader-Willi Syndrome

Prader-Willi Syndrome (PWS) is a rare genetic disorder. It causes poor muscle tone, low levels of sex hormones and a constant feeling of hunger.

Reviewed Reviewed by a registered pharmacistGeneral information

Also called: PWS

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Prader-Willi Syndrome

Prader-Willi Syndrome (PWS) is a rare genetic disorder. It causes poor muscle tone, low levels of sex hormones and a constant feeling of hunger. The part of the brain that controls feelings of fullness or hunger does not work properly in people with PWS. They overeat, leading to obesity.

Babies with PWS are usually floppy, with poor muscle tone, and have trouble sucking. Boys may have undescended testicles. Later, other signs appear. These include:

  • Short stature
  • Poor motor skills
  • Weight gain
  • Underdeveloped sex organs
  • Mild intellectual and learning disabilities

There is no cure for PWS. Growth hormone, exercise, and dietary supervision can help build muscle mass and control weight. Other treatments may include sex hormones and behavior therapy. Most people with PWS will need specialized care and supervision throughout their lives.

It sits within Mental Health and Behavior and Genetics/Birth Defects.

The lead U.S. institute for this subject is the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Prader-Willi Syndrome

152 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

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Genetics

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Prader-Willi Syndrome. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Prader-Willi Syndrome, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.