Prader Willi

What is Prader-Willi Syndrome?

Prader-Willi syndrome is a rare genetic disorder.

It is characterized by physical, mental, and behavioral differences as well as an insatiable appetite which often leads to obesity.

People with PWS have an insatiable appetite that leads to a strong urge to eat. Unfortunately, this can lead to excessive weight gain.

What Causes Prader-Willi Syndrome?

Prader-Willi syndrome is caused by a genetic condition. It typically occurs when there is a deformity in the 15th chromosome. This results in missing or unexpressed genes on that chromosome.

The majority of cases happen as a result of a deletion (loss) of part of the chromosome. It can also be caused by a genetic mutation or a problem with the imprinting of genes on the chromosomes.

What are the Signs and Symptoms of Prader-Willi Syndrome in an Infant?

The signs and symptoms of Prader-Willi Syndrome (PWS) in an infant can be quite varied. Some of the most common symptoms include:

  • Poor muscle tone
  • Weak cry
  • Feeding difficulties
  • Slow growth rate
  • Delayed development milestones
  • Hypotonia (weakness)
  • Poor feeding
  • Obesity
  • Short stature in adulthood
  • Learning disabilities

Many infants with PWS also have a characteristic facial appearance which is usually characterized by:

  • Almond shaped eyes
  • A narrow forehead
  • A turned-up nose

What are the Signs and Symptoms of Prader-Willi Syndrome in a Child?

Signs and symptoms of PWS usually become apparent during early childhood and may include:

  • Hypotonia (decreased muscle tone)
  • Eating excessively, leading to obesity
  • Short stature
  • Development delays, especially in speech and language acquisition
  • Intellectual disability or learning difficulties
  • Behavioral problems, including obsessive-compulsive behaviors and tantrums
  • Difficulty sleeping
  • Scoliosis (a curvature of the spine)
  • Low pain threshold
  • Hypogonadism (not normal functioning of the tests in males or ovaries in females)
  • Facial features may include almond-shaped eyes, a narrow face and forehead, and a thin upper lip.

Risk Factors

Risk factors for Prader-Willi syndrome include:

  • A deletion of genetic material from chromosome 15, inherited from the father.
  • Uniparental disomy (UPD), or two copies of chromosome 15 inherited from the mother instead of one copy from each parent.
  • Imprinting defects, can occur when the genetic material from one parent has been improperly marked.
  • Rare mutations in specific genes associated with Prader-Willi syndrome.

It is important to note that most cases of Prader-Willi syndrome are not inherited. In fact, only about 5 to 10 percent of cases are caused by an identifiable gene mutation or change.

The majority of cases are caused by a random, spontaneous mutation.


Prader-Willi Syndrome (PWS) is usually diagnosed with a physical examination, chromosome testing, and genetic testing.

The physical exam may reveal the characteristic facial features of PWS include:

  • Almond-shaped eyes
  • An undersized jaw
  • Thin upper lip

A doctor may also order chromosome testing to look for the deletion or rearrangement of genetic material.

Once these tests results are done, a diagnosis can be made, and treatment can begin.


The most effective treatment for Prader-Willi syndrome is a combination of the following strategies:

These may include:

  1. Growth hormone therapy to help with growth issues and improve muscle tone
  2. A very strict diet helps control food intake, including portion control and regular meals.
  3. Exercise to help control weight and improve overall health
  4. Behavioral therapies to address problems with impulsivity, aggression, and social interactions
  5. Regular medical monitoring for possible complications like diabetes or sleep apnea
  6. Educational interventions such as speech and occupational therapy
  7. Medications to help manage behavioral issues, such as antipsychotics
  8. Regular genetic counseling and support for the patient and their family to help manage the medical condition


Unfortunately, there is no known way to prevent Prader-Willi syndrome. However, early diagnosis and treatment can help manage the symptoms. It can also reduce complications, and improve the quality of life for individuals with the condition.

Treatment typically involves a combination of medical, educational, social services, and nutritional management.

Medical treatment may include:

  • Hormone replacement therapy (HRT) to stimulate growth and development
  • Medications to control behavioral problems or reduce muscle tone
  • Surgery for some complications

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