Prader-Willi Syndrome - FAQ

Who has Prader-Willi syndrome (PWS)?

Anyone can be born with PWS. It is found in males and females throughout the world.

What is PWS?

PWS is a complex genetic disorder affecting appetite, growth, metabolism, cognitive function, and behavior. Individuals with PWS typically have low muscle tone, short stature, incomplete sexual development, cognitive disabilities, problem behaviors, and the hallmark characteristics - involuntary and uncontrollable feelings of hunger and a slowed metabolism that can lead to excessive eating and life-threatening obesity. Those who have PWS need intervention and strict external controls, which may include padlocking access to food, to maintain normal weight and to help save their lives.

When does PWS occur?

It is estimated that PWS occurs in one in 12,000 to 15,000 births. Although considered a "rare" disorder, PWS is one of the common conditions seen in genetic clinics and is the most common genetic cause of obesity identified thus far.

Why does PWS occur?

Most cases of PWS are attributed to a spontaneous genetic error that occurs at or near the time of conception for unknown reasons. In a small percentage (< 2%) of individuals with PWS, a genetic mutation from the parent causes PWS in the child. It is important to identify these children as other children in the family may also be affected. A PWS-like disorder, 'acquired PWS' can also develop after birth if a part of the brain called the hypothalamus is damaged by injury or surgery.

How does the genetic error cause PWS?

The occurrence of PWS is due to the lack of several genes on one of an individual's two chromomosome 15s - the one normally contributed by the father. In most cases, there is a deletion - the critical genes are somehow missing from the chromosome. The critical paternal genes lacking in individuals 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 the defect may be helpful not only to those with PWS but to understanding obesity in otherwise normal individuals. See the Genetics section above for more information (in the Description section).

Individuals with PWS have a flaw in the part of their brain called the hypothalamus, which normally registers feelings of hunger and satiety. While the problem isn't fully understood, it is apparent that people with this flaw never feel full; they have a continuous urge to eat that they can't learn to control. To compound this problem, children with PWS need less food than typically-developing children because their bodies have less muscle and tend to burn fewer calories. Parts of the hypothalamus are also related to rage and other behavior problems.

How is PWS diagnosed?

Suspicion of the diagnosis is first assessed clinically (based on direct observation of the patient), then confirmed by specialized genetic testing on a blood sample.

What does human growth hormone (HGH) do for people with PWS?

Use of HGH is becoming standard of care for children with PWS. It should be prescribed with appropriate precautions by an experienced endocrinologist. HCH increases growth rate, particularly in the first year of treatment, and improves body composition so that muscle mass is increased and fat mass is decreased. Children treated with HGH have improved energy and physical activity levels, improved strength, agility and endurance, and improved respiratory function. For unknown reasons, it may also help with cognitive development.

What is "Food Security"?

The psychological concept of food security is an essential component of the management of individuals with PWS; the goal is to maintain food security across all settings. Food security is one of the most basic skills taught to the family or other caretakers.

Food security is achieved when food access is controlled to the extent that three criteria are established:

1. There is no doubt when, what, and how much the person with PWS will eat;
2. There is no hope of receiving any more; and
3. There is no disappointment due to false expectations.

Food security = No doubt + No hope + No disappointment.

When food access is restricted, individuals with PWS require no doubt about their meals and snacks. Menus are planned ahead and posted; calories are controlled, but the amount of food presented can still be generous. Although the timing of the meals and snacks remains fixed, it is not focused on the clock; it is set by the sequence of activities across the day. This concept is critical to the achievement of flow through the day.

Does the overeating with PWS begin at birth?

No, in fact newborns with PWS often have difficulty obtaining enough nourishment because low muscle tone impairs their sucking ability. They may be said to have "failure to thrive", which means not gaining expected growth. Many require special feeding techniques or tube feeding for several months or more after birth until muscle control improves. Sometime in the following years, usually before school age, children with PSW develop an intense interest in food and can quickly gain excess weight if calories aren't restricted.

Do diet medications work for the appetite problems in PSW?

Unfortunately, no appetite suppressant has worked consistently for people with PWS. Most require an extremely low calorie diet all their lives and must have their environments designed so that they have very limited access to food.

What is the Red, Yellow, Green System of weight management?

The Red, Yellow, Green System (RYG) was originally developed for obesity management in preteens. The system has been adapted for individuals with PWS as a way to put necessary limits and structure in place. RYG is effective for the prevention and treatment of obesity and also decreases food-centered behaviors.

What kinds of behavior problems do people with PWS have?

In additon to their involuntary focus on food, and food-centered behaviors, individuals with PWS tend to have obsessive/compulsive behaviors not related to food, including repetitive thoughts and verbalizations, collecting and hoarding of possessions, picking at skin irritations, and a strong need for routine and predictability. Frustration or changes in plans can easily set off a loss of emotional control in someone with PWS, ranging from tears to temper tantrums to physical aggression. The essential strategies for minimizing difficult behaviors in PWS are careful structuring of the person's environment and consistent use of positive behavior management and supports.

Does early diagnosis help?

While there is no medical prevention or cure, early diagnosis of PWS gives parents time to learn about and prepare for the challenges that lie ahead and to establish family routines that will support their child's diet and behavior needs from the start.

How do I help my other children deal with having a sister or brother with Prader Willi syndrome?

Research on families with children with various disabilities often finds that children are strengthened, not harmed, by having a sibling with special needs, although having a sibling with disabilities makes life more complicated. Sibling workshops have been designed to help with those problems (for example see Sibshops: workshops for siblings of children with special needs) and, for some problems, individual or family counseling may be necessary. For an interesting viewpoint, see the book The Normal One, written by a typically-developing sibling of a child with disabilities. [Safer: 2002]

What does the future hold for people with PWS?

With help, individuals with PWS can expect to accomplish many of the things their "normal: peers do - complete school, participate in their outside areas of interest, be a productive worker under the right conditions, even move away from the family home. They do, however, need a significant amount of support from their families and from school, work, and residential service providers, both to achieve these goals and to avoid obesity and the serious health consequences that accompany it. Even those with IQs in the normal range need lifelong diet supervision and protection from food availability. Although in the past many people with PWS died in adolescence or young adulthood, prevention of obesity can offer those with the syndrome the probability of having a normal life span.

How can I get more information about PSW?

Contact Prader-Willi Syndrome Association (USA).