Important

It is possible that the main title of the report Prader Willi Syndrome is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.

Synonyms

• Cryptorchidism-Dwarfism-Subnormal Mentality
• HHHO
• Hypogenital Dystrophy with Diabetic Tendency
• Hypotonia-Hypomentia-Hypogonadism-Obesity Syndrome
• Labhart-Willi Syndrome
• Prader-Labhart-Willi Fancone Syndrome
• Willi-Prader Syndrome

Disorder Subdivisions

None

General Discussion

Prader-Willi syndrome is a genetic disorder characterized by diminished muscle tone (hypotonia), feeding difficulties, and failure to grow and gain weight (failure to thrive) during infancy; short stature; genital abnormalities; and mental retardation. In addition, beginning at approximately age six months to six years, affected individuals may develop excessive body weight (obesity), especially in the lower regions of the body (e.g., lower abdomen, thighs, buttocks). Progressive obesity results from lack of physical activity and excessive intake of food, which may be associated with no feeling of satisfaction (satiety) after completing a meal, an obsession with eating, unusual food rituals, and binge-type eating habits. Individuals with Prader-Willi syndrome may also have a characteristic facial appearance due to certain features, including almond-shaped eyes, a thin upper lip, and full cheeks. Additional abnormalities may include crossing of the eyes (strabismus); unusually small hands and feet; sideways curvature of the spine (scoliosis); or mild, moderate, or severe mental retardation. Children with the disorder may also tend to have an unusual, nasal voice; difficulties articulating speech; and outbursts of anger and other behavioral abnormalities. Without appropriate treatment, individuals with severe progressive obesity may have an increased risk of cardiac insufficiency; a condition in which there is insufficient secretion of the hormone insulin (diabetes mellitus); or other serious conditions that may lead to potentially life-threatening complications.

In most affected individuals, Prader-Willi syndrome appears to occur spontaneously (sporadically) for unknown reasons. However, some familial cases have been reported. Sporadic and familial cases are thought to be caused by deletion or disruption of certain adjacent genes on the long arm (q) of chromosome.