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

These 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 (hypotonia)
  • learning difficulties
  • lack of sexual development
  • behavioural problems, such as temper tantrums or stubbornness

Read more about problems associated with Prader-Willi syndrome.

What causes Prader-Willi syndrome?

Prader-Willi syndrome is caused by a genetic defect on chromosome number 15, which happens purely by chance.

The condition 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.

Read more about the causes of Prader-Willi syndrome.

Diagnosing Prader-Willi syndrome

Prader-Willi syndrome can usually be confirmed by carrying out genetic tests.

A checklist of symptoms that are typical of Prader-Willi syndrome is often used to identify children who should be tested.

Read more about how Prader-Willi syndrome is diagnosed.

Living with Prader-Willi syndrome

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

Trying to get your child to stick to a healthy, balanced diet and maintain a normal weight is one of the most important parts of caring for a child with Prader-Willi syndrome. It's also probably one of the most challenging and frustrating.

If children are allowed to eat as much as they want, they'll quickly become dangerously overweight. A child with the syndrome can eat three to six times more than other children of the same age and 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.

Read more about managing Prader-Willi syndrome.


While Prader-Willi syndrome itself isn't life- threatening, the compulsive eating and resulting weight gain can be.

Young adults with the syndrome often develop obesity-related conditions usually seen in older adults, such as type 2 diabetes and heart failure. If the obesity isn't treated, a person with the syndrome 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. Due to the potential risk of choking, all parents of a child with Prader-Willi syndrome are advised to learn the Heimlich manoeuvre. 

Read more about what to do if someone is choking.

If a child with Prader-Willi syndrome is able to follow a restricted diet and control their weight, there's no reason why they can't 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's unlikely they'll be able to live fully independent lives.


The Prader-Willi Syndrome Association UK (PWSA UK) provides information and support for people whose lives are affected by PWS. You can call the PWSA helpline on 01332 365676.

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

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: 28/11/2014

Next review due: 28/11/2016