Prader-Willi syndrome – Pictures, Symptoms, Causes, Treatment, Life Expectancy

What is Prader-Willi syndrome?

It is an uncommon congenital condition that is characterized by presence of varied mental, physical, and behavioral abnormalities. One of the main features of Prader-Willi syndrome is a perennial sense of hunger which typically commences a year after birth.

Individuals affected by Prader-Willi syndrome have a constant desire to keep eating and are generally unable to manage or control their weight. Most of the health complications associated with Prader-Willi syndrome arise due to obesity.

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Parents with Prader-Willi syndrome affected children need to consult an array of specialists to manage the varied signs and symptoms as well as prevent the susceptibility to development of medical complications.

Symptoms of Prader-Willi syndrome

The signs and symptoms of Prader-Willi syndrome typically occur in 2 stages. Infants may elicit the below listed symptoms in the 1st year of life:

  • Affected infants may show unique facial features such as tapering of the head near the temples, eyes shaped liked almonds, thin upper lip, and downward facing mouth.
  • Prader-Willi syndrome affected children may also exhibit hypotonia or poor muscle tone. Babies may feel like rag dolls or floppy when held. They may rest on loosely stretched knees and elbows.
  • Reduced muscle tone can result in poor sucking reflex leading to feeding difficulties. This eventually leads to slow gain of weight and failure to flourish.
  • Unusual tiredness, weak cry, difficulties in waking up, and poor response to stimulation are also noticed.
  • Prader-Willi syndrome affected babies may also suffer from strabismus wherein the eyes may lack coordination or may not move together. Hence, the eyes may wander to the side, or be cross.

The below listed signs and symptoms may appear between one to four years of age:

  • Babies with Prader-Willi syndrome will have a continuous craving for food leading to rapid weight gain. As affected children are perennially hungry, they may frequently consume large portions of food. Abnormal food seeking behaviors like eating frozen food or garbage, or hoarding food is also observed.
  • Poor physical development and growth is evident. The feet and hands may be shorter along with overall reduced muscle mass. Prader-Willi syndrome affected adults are typical shorter than other members of the family.
  • The testes and ovaries may secrete minimal or no sex hormones thereby causing a disorder called hypogonadism, eventually resulting in partial growth at puberty, underdeveloped sex organs, and infertility in almost all Prader-Willi syndrome patients. Men may elicit decreased or no facial hair and their voices may never deepen fully. Women may never menstruate or commence menstruating only in their thirties.
  • Minor to moderate cognitive impairment is evident in all patients. Some form of learning disabilities is present even in patients with no substantial cognitive deficits.
  • Affected children may experience speech delays. Speech may occur only after two years. Poor diction and other speech problems may persist.
  • Prader-Willi syndrome affected toddlers usually elicit delays in motor development and in reaching different developmental milestones. Sitting without assistance may occur after 12 months while walking may take 24 months or more.
  • Different behavioral problems such as stubbornness and temper tantrums, particularly when denied food, may be noticed. Affected children may also develop OCD which causes repetitive behaviors or unnecessary recurrent thoughts, or both. Rectal gouging, skin picking, and other mental health conditions may also develop.
  • Lots of children affected by Prader-Willi syndrome may develop scoliosis or abnormal curve of the spine
  • Sleep apnea, disturbances in the usual sleep cycles, and other kinds of sleep disorders may occur in some infants with Prader-Willi syndrome. Obesity can aggravate sleep anomalies.

Other uncommon signs and symptoms associated with Prader-Willi syndrome include:

  • Myopia or nearsightedness
  • High tolerance for pain
  • A lighter skin tone as opposed to other family members


Prader-Willi syndrome is a genetic condition caused due to mutations in a specific gene or genes. Doctors are not aware of the exact gene that is responsible for causing Prader-Willi syndrome. However, it is known that the defective gene occurs in a certain area of chromosome 15.

All genes, other than the sex genes, form in pairs wherein each copy of the gene is inherited from the father and mother. Both the copies are generally active or expressed. On the other hand, some gene types may also act alone wherein only one copy needs to be active.

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Prader-Willi syndrome is caused when some paternal genes that should be active remain unexpressed due to following reasons:

  • Inheritance of two copies of chromosome 15 from the mother and none from the father
  • Missing paternal genes on chromosome 15
  • The paternal genes on chromosome 15 may be mutated, defective, or have errors.

The genetic abnormality associated with Prader-Willi syndrome affects normal functioning of the hypothalamus. It is a part of the brain which regulates different bodily functions like thirst and hunger and also secretes hormones which causes release of certain substances essential for growth and sexual development. Hypothalamus malfunction, arising out of Prader-Willi syndrome genetic defect, thus causes different problems in the above listed functions leading to deficient growth, insatiable hunger, sex-organ irregularities and other distinctive features of this genetic disorder.

Life expectancy of Prader-Willi syndrome

There is no standard life expectancy for people affected by Prader-Willi syndrome. Patients who are able to adhere to a diet and control their weight, thereby avoiding obesity altogether, are more likely to live a complete life. Controlling obesity is of paramount important as extreme obesity can result in cardiac and lung failure as well as fatalities. Proper treatment to control hunger pangs can allow patients of Prader-Willi syndrome to live longer.

Treatment of Prader-Willi syndrome

Treatment of Prader-Willi syndrome in infants includes the following:

  • Growth hormone treatment for enhancing metabolism, thereby increasing growth, decrease body fat, and better muscle tone.
  • A high-calorie formula may be needed to overcome feeding difficulties and help the baby gain weight. Older children may need a healthy, low-calorie diet to prevent obesity.
  • Children with Prader-Willi syndrome may also need hormone replacement therapy to replenish the decreased levels of sex hormones. This therapy can also reduce the risk to developing osteoporosis
  • Varied therapies such as speech therapy to enhance articulation and verbal skills, physical therapy to aid movements, and occupational therapy for imparting everyday skills may also help.
  • Mood disorders, OCD, and other mental health problems may require the assistance of a psychiatrist or a psychologist.

Adults with Prader-Willi syndrome may also require supervision and specialized care for the remainder of their lives.

 Prader-Willi syndrome pictures

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