About PWS

Symptoms of PWS        FAQs       Medical Issues 

What is Prader-Willi Syndrome (PWS)?

PWS is a rare complex genetic disorder that typically causes low muscle tone, short stature, incomplete sexual development, cognitive disabilities, problem behaviors, and a chronic feeling of hunger that can lead to excessive eating and life-threatening obesity. It is estimated that only one in  15,000 people has PWS. PWS is found in people of both sexes and all races.Those with PWS need strict environmental adaptations and intervention which could including locking food items in order to maintain normal weight and to help save their lives There is no cure for Prader Willi Syndrome yet.

What is the Cause of Prader-Willi Syndrome?

Basically, the occurrence of PWS is due to lack of several genes on one of an individual’s two chromosome 15’s – the one normally contributed by the father.  In the majority of cases, there is a deletion – the critical genes are somehow lost from the chromosome.  In some of the remaining cases, the entire chromosome from the father is missing and there are instead two chromosome 15’s from the mother (uniparental disomy).  The critical paternal genes lacking in people with PWS have a role in the regulation of appetite.  This is an area of active research in a number of laboratories around the world, since understanding this defect may be very helpful not only to those with PWS, but to understanding obesity in otherwise normal people.

People with PWS have a flaw in the hypothalamus part of their brain, which normally registers feelings of hunger and satiety.  While the problem is not yet fully understood, it is apparent that people with this flaw never feel full; they have a continuous urge to eat that they cannot learn to control.  To compound this problem, people with PWS need less food than their peers without the syndrome because their bodies have less muscle and tend to burn fewer calories. (Courtesy PWSA USA)

How is Prader-Willi syndrome diagnosed?

A blood test can confirm a diagnosis in most cases. 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. (credit PWCF)