what is the life expectancy of PWS
People with Prader-Willi syndrome (PWS) can live well into adulthood. Causes of mortality are usually obesity-related cor pulmonale and respiratory failure

People diagnosed with Prader-Willi syndrome (PWS) usually live well into adulthood. The most common causes of mortality are obesity-related cor pulmonale and respiratory failure. 

People with PWS who are not treated with growth hormone have been seen to have a mortality rate of about 3% every year between the ages of 6-56, compared to 0.13% in the general population under age 55.

What is Prader-Willi syndrome?

Prader-Willi syndrome is a genetic disorder that causes poor muscular tone (severe hypotonia), feeding problems, and delayed growth in infants. Affected children often begin to eat excessively because they are always hungry and develop obesity in later infancy or early childhood. 

PWS is caused when chromosome 15 genes are either missing or inactive. The majority of cases are not inherited and occur at random. A genetic mutation that causes PWS can be inherited in a small percentage of cases.

What are the signs and symptoms of Prader-Willi syndrome?

Short stature, hypogonadism, developmental delays, cognitive impairment, and specific behavioral features such as temper tantrums, stubbornness, and obsessive-compulsive tendencies are common signs and symptoms. 

Signs and symptoms vary according to age.

Fetal stage or during birth

  • Reduced fetal movements 
  • Abnormal fetal position 
  • Cesarean birth 
  • Hypotonia 
  • Difficulty breathing 
  • Hypogonadism

Early childhood

  • Reduced intellect
  • Excessive sleeping 
  • Speech delay 
  • Short stature 
  • Obesity 
  • Increased hunger 
  • Poor psychomotor development 
  • Delayed puberty 
  • Crossed eyes
  • Poor genital development 


  • Infertility 
  • Hypogonadism 
  • Increased susceptibility to diabetes mellitus
  • Less pubic hair 
  • Decreased intelligence 
  • Obesity 
  • Incomplete sexual development 

Additional accessory features

  • Prominent nasal bridge 
  • Almond eyes 
  • Narrow forehead 
  • Stretch marks 
  • Thin upper lip 
  • Excessive body fat 

Predisposed to behavioral disorders

How is Prader-Willi syndrome diagnosed?

Previously, diagnosis of PWS was made solely based on clinical presentation. Now, however, diagnosis is made with advanced genetic testing, which can detect the presence or absence of the PWS gene on chromosome 15. One such method is DNA-based methylation testing to detect the absence of the paternally contributed PWS/Angelman syndrome region on chromosome 15. 

Sometimes, PWS is misdiagnosed as Down’s syndrome.

How is Prader-Willi syndrome treated?

As a genetic condition, Prader-Willi syndrome has no cure. However, certain treatment options can help lessen the severity of the disorder:

  • During infancy, the child should receive physiotherapy and rehabilitation therapy to reduce the effect of hypotonia. 
  • During childhood, focus should be made on intellectual development.
  • Access to food, especially junk food, should be limited to control increased hunger and prevent obesity.
  • Growth hormone therapy can help promote normal physical development.
  • If there is sleep apnea due to severe obesity, positive airway ventilation may be administered.
  • Medications that increase brain serotonin levels can help manage anger issues.
  • Healthy eating habits along with regular exercise should be encouraged.

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Medically Reviewed on 10/1/2021