Prader-Willi syndrome

Last updated:

Reviewed by:

Dr Bryony Henderson

, Lead GP at Livi

Medically reviewed

Prader-Willi syndrome is a rare chromosome abnormality causing a wide range of symptoms. Find out about the symptoms, causes and management.

What is Prader-Willi syndrome?

Prader-Willi syndrome is a rare condition when some of your genetic information on chromosome 15 is missing. It’s present from birth and can affect males and females of all ethnicities. People with Prader-Willi syndrome are normally diagnosed soon after birth or in early childhood. 

What are the symptoms of Prader-Willi syndrome?

Symptoms are different in each person, but typical symptoms include:

  • Excessive hunger and overeating

  • Shorter than normal height

  • Low muscle tone – babies may be ‘floppier’ than usual at birth

  • Mild to moderate learning difficulties

  • Incomplete sexual development

  • Emotional and social immaturity that can cause behavioural difficulties

  • Skin picking that can cause sores, scarring and infection

At the beginning of life, babies may have some feeding difficulties. As they grow up, their appetite typically grows significantly. People with Prader-Willi syndrome can still feel hungry after they’ve eaten enough food. If appetite isn’t managed, it can lead to obesity. 

Children with Prader-Willi syndrome can have difficulties managing their emotions, which can lead to emotional distress. 

Adults with Prader-Willi syndrome can live independent lives. While most people will still need the right support and care, they can still work and have active social lives.

How common is Prader-Willi syndrome?

Prader-Willi syndrome occurs in about 1 in every 10,000–30,000 births. In the UK there are about 2,000 people living with Prader-Willi syndrome and between 350,000 to 400,000 people worldwide.

What causes Prader-Willi syndrome?

Prader-Willi syndrome occurs by chance when some of the genetic information on chromosome 15 is missing. There is nothing a parent could do to cause or prevent it from happening.

Human cells have 46 chromosomes, organised into 22 pairs and the sex chromosomes, X and Y. Prader-Willi syndrome occurs when a part of chromosome 15 is either not present or not working.

How is Prader-Willi syndrome diagnosed?

After birth, health care professionals may notice typical signs of Prader-Willi syndrome, particularly floppiness. A doctor will evaluate the child and if Prader-Willi syndrome is suspected, a sample of blood is taken and analysed in a lab to look for missing DNA.

Receiving a new diagnosis of Prader-Willi syndrome in your child can feel overwhelming. The Prader-Willi syndrome association has lots of resources and support for parents who have received a new diagnosis for their child.

How is Prader-Willi syndrome managed?

There is currently no cure for Prader-Willi syndrome, but your child will have support from your local child development team and a paediatrician.

Here are some examples of how common problems can be managed:

Feeding support for babies: Babies with Prader-Willi syndrome may need a feeding tube that goes up the nose and into the stomach. This may need to be in for a few months until they can feed from a bottle or breast. You will be supported by dieticians and feed specialists.

Exercise: Encourage short and regular activities. People with Prader-Willi syndrome may experience low energy levels, so doing 5-10 minutes of exercise at a time can help. Your care team can help to recommend a suitable exercise plan.

Hormone treatments: Children can be given human growth hormone. This can make them grow taller and develop more muscle mass which can help with exercise.

Managing skin picking: It’s important to keep nails short, wear long clothes, and spot infections early for antibiotic treatment. Therapy and antidepressants can also help in older children.

Managing weight and diet: This is very important when caring for someone with Prader-Willi syndrome and can be one of the biggest challenges. You can access lots of support and advice from experts and charities to help with this. Some general advice includes:

  • Follow a healthy balanced diet with regular mealtimes from an early age

  • Avoid sweets, sugary items, and high-calorie snacks

  • Serve small portions of carbohydrates like pasta, rice, and bread

  • Increase vegetables, salads, and fruits

  • Avoid eating food outside of mealtimes, potentially by locking cupboards, fridges, and bins if needed

The Prader-Willi syndrome association has lots of detail on their website about support you can give your child and how this will change as they grow up.

Life expectancy for Prader-Willi syndrome

Sadly, people with Prader-Willi syndrome have a reduced life expectancy. The average life expectancy is 30 years, but people have been known to live into their 60s.

When should I speak to a doctor?

Once diagnosed, you should be connected with a care team who will see you regularly. If you are worried about any symptoms in your child or changes then it is important that you call your GP or your care team immediately for advice.

If you suspect your child may have Prader-Willi syndrome you can see a doctor who will be able to assess the need for further testing.

Last updated:
Reviewed by:
Dr Bryony Henderson, Lead GP at Livi