• Prader-Willi Syndrome

    (Prader-Labhart-Willi Syndrome)


    Prader-Willi syndrome (PWS) is group of symptoms caused by a rare genetic disorder. It can cause a variety of problems with growth and development. The severity can and specific symptoms are different for each person. A signature sign of PWS is an extreme urge to eat. This can lead to obesity and other health problems.


    PWS is caused by a random genetic defect. The defect is most often caused by a gene from the father.
    Genetic Material
    Chromosome DNA
    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 eyes
    • Strabismus (misalignment of the eyes)
    • Thin upper lip
    • Downturned mouth
    • Narrow forehead
    Other symptoms of PWS can change as the child ages.
    As an infant the child may have:
    • Difficulty feeding
    • Failure to thrive (not growing as expected)
    • Decreased muscle tone
    • Decreased reflexes
    • 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 leading to early-onset obesity
    As the child gets older, additional symptoms may include:
    • Insatiable hunger, resulting in compulsive eating and often obesity
    • Continuing behavior problems, such as:
    • Learning disabilities
    • Low to normal IQ
    • Incomplete sexual development, and infertility as an adult
    • Sleep problems
    • Tire easily
    • High threshold for pain
    • Insensitivity to temperature extremes


    The doctor may suspect PWS based on your child's symptoms. Some symptoms are very 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 "shut off" 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 can not 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 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

    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 your child's development.
    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 guidelines for preventing PWS.


    March of Dimes http://www.modimes.org

    Prader-Willi Syndrome Association http://www.pwsausa.org


    Foundation for Prader-Willi Research http://www.onesmallstep.ca/

    The Hospital for SICK Kids http://www.sickkids.ca/


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

    Missouri Developmental Disability Resource Center website. Available at: http://www.moddrc.org/ .

    Prader-Willi syndrome. American Family Physicians website. Available at: http://www.aafp.org/afp/2005/0901/p827.html . Published September 2005. Accessed December 13, 2012.

    Prader-Willi syndrome. Brain Foundation website. Available at: http://brainfoundation.org.au/a-z-of-disorders/48-prader-willi-syndrome . Accessed December 13, 2012.

    Prader-Willi syndrome. Foundation for Prader-Willi Research website. Available at: http://fpwr.org/about-prader-willi-syndrome . Accessed December 13, 2012.

    Smith’s Recognizable Patterns of Human Malformation . 6th ed. Elsevier Saunders, 2006.

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

    5/17/2012 DynaMed's Systematic Literature Surveillance DynaMed's 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 Apr 16. [Epub ahead of print]

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