Prader-Willi Syndrome

What is Prader-Willi Syndrome?

Resulting in reduced muscle tone, decreased sex hormone levels, and overeating due to a lack of fullness and an inability to control hunger sensations, Prader-Willi Syndrome (PWS) is a rare genetic condition characterized by weight and muscle coordination issues. PWS is caused by a genetic abnormality generally affecting parental genes in chromosome 15 and often requires lifelong care and supervision.

What are the Symptoms of Prader-Willi Syndrome?

Children born with PWS often display signs of weak muscle tone and sometimes have difficulty nursing. Testicles may not descend on boys. Babies with PWS tend to have poor eye coordination and distinct facial features such as a noticeable narrowing of the head near the temples and almond-shaped eyes.

Additional signs of PWS may include:

  • Unexplained weight gain
  • Learning disabilities
  • Below average height
  • Poor motor skills
  • Poor responsiveness
  • Difficulty sleeping

Prader-Willi Syndrome Causes

Prader-Willi Syndrome is caused by an error occurring in one or more genes. The error itself is that some paternal genes that should have expressed themselves are not doing so. These genes are located in a specific region of chromosome 15, and there are three primary reasons why they do not express themselves.

  • All of the paternal genes that are supposed to be located in chromosome 15 are missing.
  • There are two copies of chromosome 15 from the mother and none from the father.
  • The paternal genes on chromosome 15 have an error or defect.

While doctors know the reason why this error occurs, they do not know all of the mechanisms that contribute to the error occurring.

Prader-Willi Syndrome is no more likely to occur in one gender versus another. Ethnicity is not thought to be a factor in the error occurring, although there is evidence that suggestions people of African descent are less severely affected than others.

Many, but not all, cases of Prader-Willi syndrome occur randomly.

How is Prader-Willi Syndrome Treated?

In addition to weight monitoring, treatment may include serotonin reuptake inhibitors to minimize obsessive-compulsive behaviors, sex hormone replacement, dietary counseling, and speech therapy. Diagnosis is based on presented symptoms and confirmed by a blood test. Growth hormone therapy may increase flexibility and help offset development and muscle coordination issues. Surgery is sometimes performed to correct genital abnormalities.

Physical and Behavioral Therapy

Muscle weakness is often addressed with physical therapy and exercise recommendations based on ability. Regular exercise has been shown to encourage normal motor development in younger children and develop more lean muscle mass in older children. Behavioral therapy is sometimes recommended to deal with emotional issues and teach lifestyle management strategies.

PWS isn’t curable, although the condition is considered manageable. Since most health issues linked to PWS are weight-related, regular exercise and monitoring of eating habits is often necessary to reduce the risk of obesity due to food-seeking tendencies. Some people with the condition experience eye problems and have a noticeable curvature of the spine (scoliosis).

Prader-Willi Syndrome Prevention

Prader-Willi syndrome is a genetic disorder that is present at birth. There is no way to prevent it from happening, but some complications of the condition can be reduced or prevented by working with a care team to create a lifetime management plan.

For parents of children with Prader-Willi syndrome, the plan set in place will likely include the following:

  • hormone level management
  • keeping to a strict meal plan schedule
  • regular daily activity
  • setting firm daily schedule and behavior expectations
  • regular medical care

Parents who already have a child with Prader-Willi are encouraged to get genetic counseling before having any more children to assess the risk of having another child with the condition, as are individuals with a family history of the condition.

Last Reviewed:
October 09, 2016
Last Updated:
January 11, 2018