Prader-Willi syndrome is genetic syndrome that affects one in every 12,000-15,000 people of both sexes and all races and ethnic groups. It is caused by a disorder of chromosome 15.

To learn more about genetics and to better understand how genes cause syndromes, see Your Child: Genetic Syndromes.

What are the features of children with PWS?

The major features are obesity, cognitive impairment, behavior problems, poor muscle tone, and less than normal sex hormones (hypogonadism). Other typical features include:

• Low muscle tone (hypotonia or floppy baby).
• Feeding problems and poor weight gain in infancy.
• Extreme hunger, overeating, obsession with food after infancy.
• Big weight gain between one and six years of age. This leads to morbid obesity if no steps are taken to help.
• Distinctive facial features: narrow face, almond shape eyes, small mouth with thin upper lip and down-turned corners.
• Hypogonadism —incomplete sexual development, undescended testicles, small penis, delayed puberty.
• Developmental delay, including mild to moderate mental retardation and learning difficulties.
• Infants and children are typically happy and loving and exhibit few behavior problems.
• Older children and adults have problems with behavior regulation, such as difficulties with transitions and unanticipated changes.
• Other behavior problems may include: temper tantrums, violent outbursts, obsessive/compulsive behavior, stealing, lying and being argumentative, rigid, manipulative and possessive.
• Short stature, small hands and feet.
• Fair skin.
• Speech problems.
• Skin picking, which can cause sores.

What causes Prader-Willi syndrome? Is there a test for it?

The syndrome is caused by genetic deletions on Chromosome 15. The mechanism is a bit complicated. If you want to know more, visit the links below. Genetic testing is available for PWS, and people with the signs and symptoms of PWS should get tested. The types of tests and how they work are reviewed in the following links:

• The Genetics of Prader-Willi Syndrome: An Explanation for the Rest of Us
• Gene Tests-Gene Clinics: Prader-Willi Syndrome has lots of fairly academic information on inheritance, genes, genetic testing, and prenatal testing. You can register for free to get the full review.

• Severe obesity is the major medical problem
• Obesity-related problems—including diabetes, high blood pressure, chronic venous insufficiency (leading to ulcers in legs and feet), cellulitis, and hypoventilation
• Strabismus (crossed eyes) may require surgical correction
• Scoliosis
• Osteoporosis can occur earlier than usual and can cause fractures
• Sleep disturbances and sleep apnea
• Bedwetting
• Dental problems—including soft tooth enamel, thick saliva, poor oral hygiene, teeth grinding

There is no cure for PWS at this time. There are lots of health problems that need to be treated, though. With early diagnosis and a proactive approach, these kids' health, growth, and development can thrive.

• Weight management is a major task of parents of kids with PWS. These kids need a balanced, low calorie diet with vitamin and calcium supplements, along with plenty of exercise. You will probably need to restrict access to food by locking your cabinets and refrigerator. No medication or surgical intervention has been found to eliminate the need for strict dieting.
• Growth hormone is a common medication used in PWS. It increases muscle mass and function, may allow for a higher daily calorie intake, and helps kids grow taller. The brochure, A Comprehensive Team Approach to the Management of PWS is available in English, German and Greek. It discusses the use of Growth Hormone to treat PWS. Please note that the pharmaceutical company that produces growth hormone medication funded this brochure.
• Sex hormone replacement can lead to more normal physical development in puberty.
• Behavioral management—daily routines, structure, firm rules and limits, and positive rewards work best. Psychotropic medications may help with obsessive-compulsive symptoms and mood swings as a last resort if behavior management programs do not work.
• Physical and occupational therapy help promote motor development along with growth hormone. Speech and language therapy may help with speech delays. Early intervention and special education can help your child reach their full potential. Find out everything you need to know about early intervention and special education at YourChild: Developmental Delay.

• YourChild: Genetic Syndromes
• YourChild: Chronic Conditions
• YourChild: Developmental Delay
• YourChild: Siblings of Children with Special Needs
• Prader-Willi on Medline Plus has links to helpful information.
• The Prader-Willi Syndrome Association USA website contains tons of useful information, support groups, conferences/activities, free books and pamphlets, and links to other good websites.
• The International PWS Organization provides basic information on PWS in very many different languages.
• The Foundation for Prader-Willi Research is a group that promotes research into treatment and finding a cure for PWS. Their site offers information on treatment, new treatment trials, research, and action.

Written and compiled by Kyla Boyse, R. N.  Reviewed by faculty and staff at the University of Michigan

Updated October 2006

U-M Health System Related Sites:
U-M Pediatrics
C.S. Mott Children's Hospital

Our editorial policy
The information and links we provide are reviewed by University of Michigan developmental and behavioral pediatricians and child psychologists who are experts in child behavioral health. In choosing the links we provide, we use strict criteria to ensure that the information is accurate, and the source is reputable. As much as possible, we focus on information that is based on research. In areas where there is inadequate research, we include information compatible with prevailing expert opinion.

This website is updated regularly, but because of the dynamic nature of the Internet, we cannot be responsible for misinformation that may be accessed through the links provided. As always, this website is not a tool for self-diagnosis, and is not a substitute for professional care.

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