Prader-Willi syndrome (PWS) mainly attracts attention from the media and the public because of
its association with obesity and overeating. It is very common to see headlines such as “My child is
eating himself to death”.

While these headlines may grab attention, parents and people with PWS know that there is far
more to the syndrome than this, and are often upset by such sensationalism. Many families are
under incredible stress and feel that the general public would be far more sympathetic if they
knew the whole story, rather than part of it.

 

 

Communicating the facts

What is Prader-Willi syndrome?

Prader-Willi syndrome is a complex genetic disorder that is usually not hereditary. It can occur in
any family and, in most cases, only one child will have it. It is not an illness or a disease. It is
typically characterized by low muscle tone, short stature (when not treated with growth
hormone), incomplete sexual development, disturbed sleep patterns, cognitive disabilities,
behavioural problems, and a chronic feeling of insatiable hunger that can lead to excessive eating
and life-threatening obesity.

How common is Prader-Willi syndrome?

Different researchers have estimated that between 1 in 12,000 and 1 in 22,000 people is born with
Prader-Willi syndrome. Prader-Willi syndrome is found in people of both sexes and in all races.

How and why does Prader-Willi syndrome occur?

In each cell in our body there are 46 chromosomes. The DNA in our chromosomes determines how
we develop. Most cases of Prader-Willi syndrome are attributed to a spontaneous genetic error
that occurs at or near the time of conception. The occurrence of Prader-Willi syndrome is due to
the absence of several genes on one of an individual's two chromosome 15s - 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 15s from the mother (uniparental disomy). In a very small percentage
of cases (2 percent or less), a genetic mutation that does not affect the parent is passed on to the
child, and in these families, more than one child may be affected.