Prader-Willi syndrome

Prader-Willi syndrome is a rare genetic condition that affects growth and development.

Key points about Prader-Willi syndrome

  1. Prader-Willi syndrome is caused by a genetic problem with chromosome number 15.
  2. Around 1 in 10,000–20,000 children are born with the condition.
  3. People with this syndrome are short, want to eat all the time and have cognitive (thinking) and behavioural difficulties.
  4. Weight gain from uncontrolled eating can cause obesity and diabetes.
  5. People with Prader-Willi syndrome can lead healthy, fulfilling lives.

What causes Prader-Willi syndrome?

Prader-Willi syndrome occurs when several genes on chromosome 15 are deleted or not expressed. This happens by chance and is not passed down in families. Why it happens is unknown. This genetic change affects the part of your brain (the hypothalamus) that regulates hormones and appetite, as well as the development of muscle tone and expression of emotions. 

(Prader-Willi Syndrome Association NZ, 2015)

What are the symptoms of Prader-Willi syndrome?

Babies tend to be floppy and have trouble sucking. By about 2 years old, children with Prader-Willi syndrome tend to be short for their age, with small hands and feet, and want to eat all the time.

They may have slow physical and mental development, be slower to learn to walk and talk, be stubborn and have temper tantrums.

Other problems develop during later on, such as obesity due to over-eating, osteoporosis, sleep and breathing issues, and lack of sexual development.

How is Prader-Willi syndrome diagnosed?

Talk to your doctor if you are concerned your child has Prader-Willi syndrome. A genetic test is needed to diagnose the condition.

What is the treatment for Prader-Willi syndrome?

Treatment aims to manage the symptoms associated with this condition.

This includes:

  • a strict diet
  • exercise to build muscle mass
  • behaviour management.

Growth hormone treatment may be an option. This may lead to cognitive and other benefits as well.

Most people with Prader-Willi syndrome need specialised care and support from their families/whānau and healthcare providers throughout their lives.

Following the advice of healthcare providers in caring for your family member with Prader-Willi syndrome makes it easier for you and for them. This includes keeping food out of sight, sticking to a routine and being clear and firm in your instructions.

How can I care for myself when looking after someone with Prader-Willi syndrome?

Remember to take care of your own needs for sleep, exercise, healthy eating and time for yourself. Counselling can help. Talk to your doctor for a recommendation or find a counsellor here

It’s important that you get support for yourself (see the support options below).

Image: iStock


Prader-Willi Syndrome Association NZ Freephone 0800 4 PWS HELP
Disability services funded by the Ministry of Health 

Learn more

Prader-Willi syndrome NHS, UK
Prader-Willi Syndrome Association Australia
International Prader-Willi Syndrome Association


  1. Prader-Willi syndrome Better Health Channel, Australia, 2014
  2. Prader-Willi Syndrome Association Australia Australia, 2017
  3. Human growth hormone treatment for Prader-Willi syndrome in adolescent and adult patients – clinical evidence, safety, and guidelines Canadian Agency for Drugs and Technologies in Health, 2015
  4. Cognitive and adaptive advantages of growth hormone treatment in children with Prader-Willi syndrome Dykens EM, Roof E, Hunt-Hawkins H. J Child Psychol Psyc. 2017 Jan;58 (1): 64–74. 

Information for healthcare providers

Professional resources Prader-Willi Syndrome Association, NZ
Prader-Willi Syndrome Patient Info Professional, UK, 2015

Reviewed by

Dr Sharon Leitch is a general practitioner and Senior Lecturer in the Department of General Practice and Rural Health at the University of Otago. Her area of research is patient safety in primary care and safe medicine use.
Credits: Health Navigator Editorial Team. Reviewed By: Dr Sharon Leitch, GP and Senior Lecturer, University of Otago Last reviewed: 08 Dec 2020