Prader-Willi syndrome (PWS) is group of symptoms caused by a rare genetic problem. It can cause a variety of problems with growth and development.


PWS is caused by a random genetic defect. The defect is most often caused by a gene from the father.

Genetic Material

Copyright © Nucleus Medical Media, Inc.

Risk Factors

There are no known risk factors. About 1% may have a family history.


Some physical features common in people with PWS include:

  • Almond-shaped eyelid openings
  • Misalignment of the eyes
  • Thin upper lip
  • Downturned mouth
  • Narrow forehead
  • Small hands and feet

Other symptoms of PWS can change as the child ages.

As an infant, the child may have:

  • Difficulty feeding
  • Slow growth
  • Inability to suck well
  • A weak, squeaky cry
  • Sleepiness

As a toddler, symptoms may include:

  • Delay of normal development, such as language skills and walking
  • Behavior problems, such as temper tantrums and stubbornness
  • Short stature compared to family
  • Increased appetite

As the child gets older, additional symptoms may include:

  • Insatiable hunger
  • Continuing behavior problems, such as:
  • Learning disabilities
  • Sleep problems
  • Fatigue
  • High threshold for pain
  • Insensitivity to temperature extremes


PWS may be suspected based on your child's symptoms. Some symptoms are general. They may be associated with other types of illness. As a result, the diagnosis may not be made until early childhood.

A genetic test can help to confirm the diagnosis. This test is done with a sample of blood.


PWS will require lifetime treatment. It is managed by the caregivers of children with PWS. Key areas of treatment include:

Appetite and Weight Management

In the first year of life, children with PWS often have trouble eating enough food. Your doctor may recommend giving special formula through a tube. This will provide enough nutrition so your child can grow as expected. However, the appetite generally begins to grow out of control after the first year of life. Treatment then becomes focused on preventing obesity.

PWS affects the part of the brain that tells us that we are full. As a result, people with this syndrome will never feel full. Without this signal, anyone can easily eat too much food. In addition, people with PWS have a slow metabolism. Both of these factors can lead to excessive weight gain and obesity. This weight gain increases the risk of heart disease, diabetes, and other serious health problems.

In this case, excess eating is not a will power problem. People with PWS cannot be trained to manage their appetite. Instead, caretakers need to limit access to food. Any exposure to food needs to be supervised. Regular exercise should also be encouraged. This can help manage the weight and decrease the risk of other obesity-related health problems.

Behavior Issue Management

Infants and young children are often happy and loving. Difficult behaviors tend to develop as children with PWS get older. Some steps that may help you manage these behaviors include:

  • Daily structure and routine
  • Firm rules
  • Rewards for good behavior
  • Psychotropic drugs may be necessary

Poor sleep can also affect a child's behavior. Your doctor may be able to recommend a plan to help your child sleep. People with PWS may also tire easily. Naps during the daytime may help.


Developmental issues may be treated in a variety of ways. Growth hormones can help with poor physical growth. Your child will also have a team of specialists to monitor development.

Early Intervention

Early intervention can help to address delays in physical skills, speech, and language. The program can also assist as your child moves through school.

Additional Support

Your child may also need specialist care for other symptoms associated with PWS. This may include an eye doctor, bone specialist, or dentist.


There are no current guidelines for preventing PWS. Some side effects may be preventable with treatment.


March of Dimes

Prader-Willi Syndrome Association


About Kids Health—The Hospital for Sick Children

Foundation for Prader-Willi Research


About Prader-Willi syndrome. Foundation for Prader-Willi Research website. Available at: Accessed March 20, 2018.

McCandless SE, Committee on Genetics. Clinical report-health supervision for children with Prader-Willi syndrome. Pediatrics. 2011;127(1):195-204.

Prader-Willi syndrome. EBSCO DynaMed Plus website. Available at: Updated March 28, 2017. Accessed March 20, 2018.

Wattendorf D, Muenke M. Prader-Willi syndrome. Am Fam Physician. 2005;72(5):827-830.

5/17/2012 DynaMed Plus Systematic Literature Surveillance Siemensma EP, Tummers-de Lind van Wijngaarden RF, et al. Beneficial effects of growth hormone treatment on cognition in children with Prader-Willi syndrome: A randomized controlled trial and longitudinal study. J Clin Endocrinol Metab. 2012;97(7):2307.

Last reviewed March 2018 by EBSCO Medical Review Board Kari Kassir, MD  Last Updated: 5/11/2013