Symptoms of Prader-Willi Syndrome

Symptoms of Prader-Willi syndrome include:

  • Global hypotonia (weak muscle tone) in infancy resulting in poor suck reflex
  • Decreased fetal movement / weak cry and lethargy in infancy
  • Failure to thrive in infancy / feeding difficulties requiring special feeding techniques
  • Excessive weight gain (crossing two centile channels) between ages 1 and 6
  • Hypogonadism (reduced production of testosterone hormone)
  • Global developmental delays / learning difficulties
  • Hyperphagia (excessive appetite) / obsession with food / food foraging
  • Decreased fetal movement / weak cry and lethargy in infancy
  • Behavioral problems such as temper tantrums, violent outbursts, and obsessive/compulsive behavior; tendency to be argumentative, oppositional, rigid, manipulative, possessive, and stubborn; perseverating, stealing, and lying
  • Sleep disturbance or sleep apnea
  • Short stature (compared to the family)
  • And more (see the Diagnostic Criteria Sheet for more details)

It should be noted that symptoms such as weak muscle tone, developmental delay, short stature, and excessive weight can be significantly improved with recombinant human growth hormone medication.

How is Prader-Willi syndrome diagnosed?

A blood test can confirm a diagnosis in most cases. If you suspect your child (or you) has Prader-Willi syndrome print the Diagnostic Criteria sheet and mark the traits you have observed then discuss with your doctor. Consultation with a geneticist is recommended. Ideally you should start with a methylation test which detects approximately 99% of PWS cases. If the methylation test is positive you will then need either a FISH test or a PCR test to determine the sub-type, deletion or UPD respectively. There have been numerous instances when a negative FISH test results in a family being told their child does not have PWS only later (sometimes much later) to discover via a methylation or PCR test that their child has the UPD sub-type.