Prader Willi Syndrome

What is Prader Willi Syndrome?

Prader Willi Syndrome is a genetic disorder caused by a lack of genetic material in chromosome 15. The genetic defect causing inactivity of chromosome 15 can occur in one of three ways:

  1. Most often, part of the chromosome 15 that was inherited from the person’s father is missing, or deleted.
  2. An individual inherits two chromosome 15’s from their mother, and none from the father.
  3. A small genetic mutation causes the genetic material in chromosome 15 to be inactive.

The symptoms of Prader-Willi syndrome are believed to be caused by dysfunction of a portion of the brain called the hypothalamus. The hypothalamus is a small endocrine organ at the base of the brain that plays a crucial role in many bodily functions, including hunger and satiety, temperature and pain regulation, fluid balance, puberty, emotions, and fertility. Although hypothalamic dysfunction is believed to lead to the symptoms of PWS, it is unclear how the genetic abnormality causes hypothalamic dysfunction.

There are two generally recognized stages of the symptoms associated with PWS:

Stage 1:

  • Infants are hypotonic or “floppy”, with very low muscle tone.
  • Weak cry and a poor suck reflex are typical.
  • Usually unable to breastfeed and frequently require tube feeding.
  • May suffer from “failure to thrive” if feeding difficulties are not carefully monitored and treated.
  • As these children grow older, strength and muscle tone generally improve.
  • Motor milestones are achieved, but are usually delayed.

Stage 2:

  • This stage most commonly begins between ages 2 and 6 years old.
  • An unregulated appetite is common.
  • Lack normal hunger and satiety cues.
  • They usually are not able to control their food intake and will overeat.
  • Food seeking behaviors are very common.
  • Metabolic rate is lower than normal.

Other potential symptoms include:

  • Learning disabilities
  • Difficulty with speech
  • Obsessive-compulsive behaviours
  • Skin picking
  • Irregular sleep patterns
  • Higher pain threshold
  • Difficulty controlling emotions