Prader-Willi Syndrome. (Ask the Doctor)
Butler, Merlin G., The Exceptional Parent
Prader-Willi syndrome (PWS) includes a collection of signs or symptoms characterized by hypotonia in infancy, obesity in early childhood, mental retardation, small hands and feet, underdevelopment of the sex organs, and a particular facial appearance.
Prader-Willi syndrome is due to a chromosome 15 abnormality, usually a deletion on chromosome number 15 involving the long arm. The deletion includes several dozen genes. Interestingly, those individuals who have PWS as a result of the deletion of part of chromosome 15 inherit that deletion from their fathers. Other people with Prader-Willi syndrome have maternal uniparental **disomy in which both chromosome 15s come from the mother. A small percentage of individuals have an imprinting mutation of genetic material or DNA from chromosome 15 that controls the activity or expression of genes.
In the majority of PWS families the recurrence risk is low (less than 1 percent), but in rare instances a father may carry an imprinting mutation and have a higher risk (possibly 50 percent) of passing on the mutation to a child with PWS. We recommend that families with PWS consult a medical geneticist to assess their risk for other children with PWS.
The major health concern in PWS is obesity, a cardinal feature. If the obesity is left uncontrolled it becomes life threatening. To successfully avoid or control obesity, a diet plan including an exercise program should be designed specifically for the individual, to meet growth needs and ensure overall good health and development.
Dietitians should be consulted regularly to assist in weight management and caloric intake. Generally the diet is calculated on the basis of the height of the child with PWS. For example, to maintain weight and achieve growth, a diet should consist of 10-12 calories per centimeter of height. About 8 calories per centimeter of height should produce weight loss.
Diet control and exercise programs are needed for people of all ages with PWS, to prevent obesity and its life threatening complications. The complications include diabetes, hypertension, breathing difficulties, heart disease and skeletal problems. Use of medications and appetite suppressants have met with only limited success.
Recently the use of growth hormone has been approved for treating people with PWS and has met with success in treating short stature and reducing fat mass. Growth hormone therapy also appears to increase muscle mass, strength and endurance, allowing for more physical activity. Exercises to increase coordination and balance are important, but should be kept simple and low in number at the beginning and increase over time. …