Prader-Willi Syndrome (PWS)

This article, discusses about a rare complex genetic condition, which usually begins in infancy. Symptoms include physical mental and behavioral abnormalities. Patient feels excessively hungry from childhood. Signs of poor muscle tone continues through childhood and in few cases gets worse. This condition is termed as Prader-Willi Syndrome (PWS). In this article, we will discuss about the different causes, symptoms, and treatment of Prader-Willi Syndrome (PWS).

Prader-Willi Syndrome (PWS)

How Is Prader-Willi Syndrome (PWS) Defined?

  • Prader-Willi Syndrome (PWS) is a complex genetic disorder, which persistently influences child to eat more food.
  • Child periodically feels hungry and demands more feeding.
  • Over eating result in morbid obesity and causes multiple systemic complications.
  • The disease is observed during infancy.
  • In this condition, there is hypotonia, feeding problems, inadequate growth, and delay in reaching developmental milestones.
  • Infant develops an intolerable appetite, which leads to overeating and results in obesity.
  • There are many instances in which people with Prader-Willi syndrome, especially those who are obese develop diabetes mellitus type II.

Causes of Prader-Willi Syndrome (PWS)

Genetic Causes of Prader-Willi Syndrome (PWS)

Gene Mutation-

  • Prader-Willi Syndrome (PWS) tends to be caused by gene mutation and loss in one specific location or region of chromosome-15.1
  • Prader-Willi Syndrome (PWS) is caused when the region of paternal chromosome 15 containing these genes is not present or missing.1, 2
  • Chromosomal Pair- Individuals in normal instances inherit one copy of this chromosome from the mother and one copy from the father. Some genes get on active only on the paternal copy.
  • Gene Activation- The gene mutation or loss between pair of chromosome results in phenomenon known as genomic imprinting.
  • Research- Several lab researches has identified gene and chromosome which causes Prader-Willi Syndrome. Future researches are directed to find the cure.

Facts about Prader-Willi Syndrome (PWS)

  • Genetic disorder
  • Missing gene is located over chromosome 15.
  • Prader-Willi Syndrome (PWS) usually develops in infants characterized by hypotonia, feeding problems and growth retardation.
  • As the child grows, there may be development of obesity and diabetes mellitus.
  • Individuals with Prader-Willi syndrome usually have moderate form of intellectual learning disabilities.
  • Behavioral symptoms- Child suffering with Prader-Willi Syndrome often exhibit abnormal behavioral symptoms temper tantrums and compulsive behavior.
  • People who have Prader-Willi Syndrome have distinct facial features. They are of short stature with small hands and feet. They tend to have underdeveloped genital areas. Most of the people with Prader-Willi Syndrome tend to be infertile.

Symptoms of Prader-Willi Syndrome (PWS)

Individuals with Prader-Willi Syndrome (PWS) as stated have symptoms of learning disabilities.They also tend to have behavioral issues with temper tantrums, compulsive behaviors etc. Sleep disorder is also a major symptom in individuals with Prader-Willi Syndrome. Some of the other symptoms of Prader Willi Syndrome are short stature, abnormally fair skin.

How Is Prader-Willi Syndrome (PWS) Diagnosed?

Some of the signs and symptoms that may warrant a blood draw to confirm Prader-Willi Syndrome (PWS) are:


  • Severe hypotonia with weak cry
  • Feeding issues
  • Narrowing of head
  • Developmental delays
  • Infant Obesity


Skeletal System

  • Short stature
  • Low motor or muscle tone- causing weakness
  • Strabismus (cross eye)
  • Scoliosis
  • Extremely flexible muscles and joint

Central Nervous System Abnormal Symptoms-

  • Excessive sleeping
  • Learning disability
  • Speech delay
  • Delayed milestone

Gonadal Development-

  • Under developed genitals
  • Delayed puberty

Weight Gain-

  • Excessive weight gain- obesity
  • Appetite- excessive eating


Central Nervous System

  • Learning disability
  • Delayed motor function

Skeletal System

  • Hypotonia
  • Extremely flexible
  • Prominent nasal bridge
  • Small hand, feet, toes and fingers.


  • Multiple bruises
  • Thin upper lips
  • Light skin
  • Less hair on skin


  • Like shape of the almond, is oblonged or almond shape.

Gonadal Development

  • Hypogonadism
  • Infertility
  • Sparse Pubic hair
  • Sexual organs under developed

Endocrinal Dysfunction

  • Diabetes mellitus

Weight Gain

  • Morbidly obese
  • Predominant central obesity

Behavioral Abnormalities

  • Excessive eating associated with excellent appetite to eat.
  • Anxiety mostly afraid of not getting enough to eat.

Psychiatric Symptoms

  • Few patients may suffer with hallucination and depression.

What is the Diagnostic Test?

Genetic Test- Diagnosis is confirmed by genetic test. Genetic test is performed to identify abnormal chromosome responsible to cause Prader-Willi Syndrome.

Treatment for Prader-Willi Syndrome (PWS)

Early clinical and lab diagnosis is important to prevent developmental complications.

Prader-Willi Syndrome (PWS) Treatment Approach-

  • Early diagnosis
  • Consult neonatologist or pediatrician if there is any doubt regarding infant's rapid weight gain.

Adequate Nutrition:

  • Since infants with Prader-Willi Syndrome have difficulty feeding due to inadequate muscle tone hence a high calorie diet is recommended for adequate weight gain and growth of the infant.

Human Growth Hormone Treatment:

  • Human growth hormone is helpful in stimulating growth and development and acts as a catalyst in converting food into energy.
  • This treatment also helps improve growth and improves muscle tone.
  • Growth hormone treatment in children helps to develop normal growth in adult.2

Sex Hormone Treatment:

  • Hormone replacement therapy is suggested for both males and females to increase the sex hormone levels, especially when they reach puberty.
  • It also reduces the risk of the child developing osteoporosis.


  • It is imperative that children with Prader-Willi Syndrome have a healthy diet habit so as to keep the child's weight under control and ensure appropriate nutrition.
  • Reduced calories and adequate protein as well as vitamin supplement improves weight control.2

Endocrinal Treatment-

  • Diabetes and hypothyroidism is treated with insulin and thyroid hormones.3

Treatment of Sleep Disorders: Treating sleep disorders promptly allows improvement in behavioral issues and promotes adequate sleep.


1.Prader-Willi syndrome and chromosome 15. A clinical discussion of 20 cases.
Mattei JF, Mattei MG, Giraud F.
Hum Genet. 1983;64(4):356-62.

2. Endocrine manifestations and management of Prader-Willi syndrome.
Emerick JE1, Vogt KS.
Int J Pediatr Endocrinol. 2013 Aug 21;2013(1):14.

3. A reduced-energy intake, well-balanced diet improves weight control in children with Prader-Willi syndrome.
Miller JL1, Lynn CH, Shuster J, Driscoll DJ.
J Hum Nutr Diet. 2013 Feb;26(1):2-9.

4. What is the value of growth hormone therapy in Prader Willi syndrome?
Arch Dis Child. 2014 Feb;99(2):166-70.

Written, Edited or Reviewed By:


Last Modified On: May 2, 2016

Pain Assist Inc.

Pramod Kerkar
  Note: Information provided is not a substitute for physician, hospital or any form of medical care. Examination and Investigation is necessary for correct diagnosis.

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