Prader-Willi syndrome (PWS) is a rare genetic condition that causes a wide range of symptoms.

Symptoms may include:

  • a constant desire to eat food, which seems driven by a permanent feeling of hunger and can easily lead to dangerous weight gain
  • restricted growth, leading to short stature
  • reduced muscle tone
  • learning difficulties
  • lack of secondary sexual development
  • behavioural problems, such as temper tantrums or stubbornness

Read more about symptoms of Prader-Willi syndrome.

Who is affected?

PWS is rare, affecting no more than one in every 15,000 children born in England. Boys and girls of all ethnic backgrounds may be affected.

There are no known factors that make giving birth to a child with PWS more likely. It is caused by a fault in the child's chromosomes, which happens purely by chance.

Read more about the causes of Prader-Willi syndrome.

Living with Prader-Willi syndrome

There is no cure for PWS, so treatment aims to manage the symptoms and associated problems. For parents, this includes dealing with their child's behavioural problems and excessive eating.

Read more about managing Prader-Willi syndrome.

Restricting your child's diet is a particularly important part of managing their condition. If children with PWS are allowed to eat as much as they want, they will quickly become dangerously overweight. They will eat three to six times more than other children of the same age, and will probably still feel hungry.

However, restricting a child's diet is not easy. They can be highly obsessive when it comes to eating, and their hunger can cause them to hide or steal food.


While PWS itself is not life threatening, the compulsive eating and resulting weight gain can be.

Younger adults with PWS often develop obesity-related conditions usually seen in older adults, such as type 2 diabetes and heart failure. If the obesity is not treated, an adult with PWS will probably die a lot younger than would normally be expected.

Compulsive eating can also cause health problems such as an abnormally expanded stomach and choking. Because of the potential risk of choking, all parents of a child with PWS are advised to learn the Heimlich manoeuvre. 

Read more about what to do if someone is choking.

If a child with PWS manages to follow a restricted diet and control their weight, there is no reason why they cannot enjoy a good quality of life and take part in activities such as voluntary or part-time work. However, because of their behavioural problems and learning difficulties, it is unlikely they will be able to live fully independent lives.

Prader-Willi syndrome

Prader-Willi syndrome is a rare genetic disorder that causes characteristics such as obesity due to an excessive appetite. A psychiatrist explains the different symptoms. Also find out how Sharon copes with her daughter Daisy’s condition, and how she prevents Daisy from overeating.

Media last reviewed: 27/03/2014

Next review due: 27/03/2016


The Prader-Willi Syndrome Association (PWSA UK) helps provide information and support for those whose lives are affected by PWS.

You can also contact the PWSA through their helpline on 01332 365676.

Special needs in children

If your child has a health condition or disability, they may need specialised healthcare and help at school

Page last reviewed: 22/11/2012

Next review due: 22/11/2014