Prader-Willi Syndrome

Prader-Willi Syndrome (PWS) is an uncommon genetic disorder. It causes poor muscle tone, low levels of sex hormones and a constant feeling of hunger. The part of the brain that controls feelings of fullness or hunger does not work properly in people with PWS. They overeat, leading to obesity.

Babies with PWS are usually floppy, with poor muscle tone, and have trouble sucking. Boys may have undescended testicles. Later, other signs appear. These include

Short stature
Poor motor skills
Weight gain
Underdeveloped sex organs
Mild mental retardation and learning disabilities

There is no cure for PWS. Growth hormone and exercise can help build muscle mass and control weight.

National Institute of Child Health and Human Development

Prader-Willi Syndrome on Wikipedia

'''Prader-Willi syndrome''' is a genetic disorder in which seven genes (or some subset thereof) on chromosome 15 are missing or unexpressed (chromosome 15q partial deletion). It was identified in 1956 by Andrea Prader, Heinrich Willi, Alexis Labhart, and Guido Fanconi of Switzerland. Prader-Willi syndrome (PWS) is characterized by severe hypotonia and feeding difficulties in early infancy, followed in later infancy or early childhood by excessive eating and gradual development of morbid obesity, unless externally controlled. All patients have some degree of mental retardation and distinctive behavioral problems. Hypogonadism is present in both males and females. Short stature is common.

Diagnosis/testing

Accurate consensus clinical diagnostic criteria exist, but the mainstay of diagnosis is genetic testing, specifically DNA-based methylation testing to detect the absence of the paternally contributed Prader-Willi syndrome/Angelman syndrome (PWS/AS) region on chromosome 15q11.2-q13. Such testing detects over 99% of patients. Methylation-specific testing is important to confirm the diagnosis of PWS in all individuals, but especially those who are too young to manifest sufficient features to make the diagnosis on clinical grounds or in those individuals who have atypical findings.

Genetics

PWS is caused by absence of the paternally derived PWS/AS region of chromosome 15 by one of several genetic mechanisms, including uniparental disomy, imprinting mutations, chromosome translocations, and gene deletions. The genes responsible for Prader-Willi syndrome are expressed only on the paternal chromosome. (Interestingly, a deletion on the maternal chromosome causes Angelman syndrome.) This is the first known instance of imprinting in humans. The risk to the sibling of an affected child of having PWS depends upon the genetic mechanism which caused the disorder. The risk to siblings is <1% ... [ Read More ]

External Resources

Prader-Willi Alliance of New York - Represents the interests of individuals in New York State with Prader-Willi syndrome, their families, and the professionals who provide services to the Prader-Willi population.

Prader-Willi Syndrome Association of Victoria (Australia) - Includes details about the organization, a diagnosis/infant guide, a general guide, members stories and links.

Williams Syndrome and Prader-Willi Syndrome - Diagnostic assessment, selected treatment services and opportunities to participate in research from the Yale University Child Study Center.

Prader-Willi Syndrome Association (USA) - Characteristics include hypotonia, insatiable appetite, obesity if food intake is uncontrolled, hypogonadism and incomplete sexual development, developmental delays, variable degrees of mental retardation or functional retardation, short stature (adult), small hands and feet, mild dysmorphology, and behavior problems which can be severe.

Ontario Prader-Willi Syndrome Association - OPWSA provides support and information to all those interested in finding out about this syndrome. A special emphasis on Canadian content.

Prader-Willi Syndrome - Suite101 - A forum to provide a support base for PWS without having to join one of the national or international associations, and to make people more aware of PWS.

The Prader-Willi Syndrome Association (UK) - Information and resources about this chromosomal disorder.

Gretton Homes - Information about the organization that offers residential care for people with Prader-Willi Syndrome.

The New Jersey Chapter of the Prader-Willi Syndrome Association - Includes news, important dates, fund raising, maps and links.

Prader-Willi Syndrome Association of South Africa - Informative regarding PWS, its symptoms, causes, prevention and treatment.

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