Prader-Willi syndrome

Prader-Willi syndrome is a rare genetic condition that causes a wide range of physical symptoms, learning difficulties and behavioural problems. It's usually noticed shortly after birth.

Symptoms of Prader-Willi syndrome

Typical symptoms of Prader-Willi syndrome include:

Read more about symptoms of Prader-Willi syndrome.

Causes of Prader-Willi syndrome

Prader-Willi syndrome is caused by a fault in a group of genes on chromosome number 15. This fault leads to a number of problems and is thought to affect part of the brain called the hypothalamus, which produces hormones and regulates growth and appetite.

This may explain some of the typical features of Prader-Willi syndrome, such as delayed growth and persistent hunger.

The genetic cause happens purely by chance, and boys and girls of all ethnic backgrounds can be affected.

It's extremely rare for parents to have more than one child with Prader-Willi syndrome.

Diagnosing Prader-Willi syndrome

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

Children may be recommended for genetic testing if they have the symptoms of Prader-Willi syndrome. Testing may be done in babies who are very floppy at birth.

Managing Prader-Willi syndrome

There's no cure for Prader-Willi syndrome, so treatment aims to manage the symptoms and associated problems. This includes managing the child's excessive appetite and behavioural problems.

One of the most important parts of caring for a child with Prader-Willi syndrome is to try to maintain a normal weight. The child should have a healthy, balanced diet, avoiding sweet treats and high-calorie items right from the start.

If children are allowed to eat as much as they want, they'll quickly become dangerously overweight. A child with the syndrome can eat 3 to 6 times more than other children of the same age and still feel hungry.

Limiting food intake can be very challenging for families. Children may behave badly to get extra food, and their hunger can make them hide or steal food.

Read more about managing Prader-Willi syndrome.

Long-term problems caused by Prader-Willi syndrome

Prader-Willi syndrome itself isn't life-threatening. However, compulsive eating and weight gain can cause young adults with the syndrome to develop obesity-related conditions such as:

If obesity is not prevented by controlling food intake, people with the condition are likely to die a lot younger than would normally be expected. If their diet is well controlled and they don't become overweight, adults can have a good quality of life and probably a normal life expectancy.

Many adults with Prader-Willi syndrome take part in activities such as voluntary or part-time work but, because of their behavioural problems and learning difficulties, it's unlikely they'll be able to live fully independent lives.

The increased appetite also means there is an increased risk of choking on food, so carers of a child with Prader-Willi syndrome are advised to learn what to do if someone is choking.


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

Information about your child

If your child has Prader-Willi syndrome, your clinical team will pass information about them on to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS).

This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.

Find out more about the register.

Video: Prader-Willi syndrome