PWS is a complex genetic disorder, identified by short stature, incomplete sexual development, characteristic behavior problems, low muscle tone, and an involuntary urge to eat constantly, which, coupled with a reduced need for calories, leads to obesity. About 1 in 14,000 people are estimated to have PWS and it’s one of the 10 most common conditions seen in genetics clinics. Although PWS is associated with an abnormality of chromosome 15, it is considered not to be an inherited condition, but rather a spontaneous genetic birth defect. PWS is found in people of both sexes and all races.

Eating problem associated with PWS begin at birth do not begin at birth. N ewborns with PWS are typically described as "floppy" and are unable to suck well enough to get sufficient nutrients -- due to the low muscle tone (hypotonia). Often they must be fed through a tube for several months after birth, until muscle control improves. Sometime in the following years however, usually by preschool age, children with PWS develop an increased interest in food and quickly gain excessive weight if calories are not restricted.

People with PWS have a flaw in the part of their brain (the hypothalamus) that determines hunger and satiety (fullness). These people never feel full enough, so they have a continuous urge to eat. People with this problem, need considerably fewer calories than normal to maintain an appropriate weight. The obesity that results is the major cause of illness in this disorder. As in the general population, obesity in PWS can cause high blood pressure, respiratory difficulties, diabetes and other problems.

Unfortunately, no appetite suppressant has worked consistently for people with PWS. Most must be on an extremely low-calorie diet all their lives and must have their environment designed so that they have very limited access to food. For example, many families have to lock the kitchen or the cabinets and refrigerator. This is where behaviour problems develop.

In addition to sometimes extreme attempts to obtain food, people with PWS are prone to temper outbursts, stubbornness, rigidity, argumentativeness, and repetitive thoughts and behaviors. Strategies to deal with these problems usually include structuring the person's environment, implementing behavioral management techniques, reward systems and occasionally drug therapy.

Early diagnosis of Prader-Willi syndrome gives parents an opportunity to manage their child's diet and avoid obesity and its related problems from the start. Since infants and young children with PWS typically have developmental delays in all areas, diagnosis may facilitate a family's access to critical early intervention services and help identify areas of need or risk.

People with PWS can accomplish many of the things their peers do: attend school, enjoy activities, get jobs, and even move away from home. However, they need a lot of help. School children with PWS are likely to need special education and related services, such as speech and occupational therapy. In community, work and residential settings, adolescents and adults often need special assistance to learn and carry out responsibilities and to get along with others. In all settings, people with PWS need around-the-clock food supervision. Get information and support from professionals and other families who are dealing with the syndrome.