Prader-Willi syndrome is a disability associated with a severe eating disorder typically leading to obesity and associated health problems such as diabetes, high blood pressure, and heart problems. PWS is named after the Swiss doctors who discovered this condition in 1956.
The specific features of PWS vary from person to person, but nearly all people with this condition have a voracious appetite over which they have little control. To control their food intake, many people with PWS are placed in specialized treatment centers or state institutions (despite their substantial cognitive abilities) because, at present, there is no known medical or psychological treatment for Prader-Willi syndrome.
People have 23 pairs of chromosomes in each of their body's cells. Chromosomes determine our eye color and height, as well as other traits. Chromosomes also regulate thousands of other bodily functions, which can have serious adverse health effects or even be fatal if the chromosomes' signals go awry.
PWS is a disorder caused by a defect on chromosome 15. PWS is called a contagious gene syndrome, meaning that several genes on chromosomes located near one another produce the cluster of features commonly seen among people with PWS.
Children and adolescence with PWS often display other unusual behavior problems. Hiding others' personal items such as treasured photographs and toiletries is common. Parents of adolescents with PWS report problems with obstinacy, argumentativeness, and hypersensitivity to what the youngsters perceive to be unfair treatment (e.g., adult attention given to another child in the family or another student in school). Children and youth with PWS often pick their skin, causing bleeding and sores that may not heal properly. as they grow into adulthood, people with PWS appear to have more problems with depression than their peers without PWS. It is unclear whether this is secondary to problems associated with excessive overeating and obesity or whether it is a primary feature of the syndrome.
One in 10,000 to 15,000 babies is born with PWS, which makes it about one-tenth as common as Down syndrome, the most familiar developmental disability. Babies with PWS are inactive and have a poor sucking reflex. They usually have to be tube fed. As they reach 10 months to 2 years of age, their appetites change radically. Suddenly, they have an insatiable appetite. Typical developmental milestones are delayed in children with PWS. On average, toddlers with PWS learn to walk when they are about 18 months old. By the time they enter kindergarten, they are nearly always overweight and are short for their age. About half of the children with PWS have very light skin and hair color (some are albinos), and the colored part of their eyes (the iris) is very pale. Some have nystagmus, a condition in which the eyes scan rapidly from side to side.
About half of children with PWS function in the low normal intellectual range (70-100 IQ), while the other half function in the mild to moderate range of mental retardation (50-70 IQ). Many children with PWS begin their schooling in mainstream settings.
By elementary school age, it is common for children with PWS to steal or hide food at home and school. They may take food from other children's lunch boxes or hide food left over from dinner under the bed to be eaten later.
Because of behavior problems surrounding food and mealtimes, children with PWS are often referred for special education services. In addition, many children with PWS have difficulties learning to read and in developing math skills. It is not clear whether these are specific learning disabilities associated with PWS or reflect a more general cognitive delay.
Youngsters with PWS do not mature sexually as rapidly as their peers. External signs of adulthood (beards and larger genitals in boys, underarm and pubic hair, enlargement of breasts in girls) may not be apparent or are delayed. As a result, adolescence and young adults with PWS look young for their chronological age. Typical adolescent rebelliousness is often exaggerated by the constant struggle with parents and teachers over assess to food.
By late adolescence, some youth with PWS begin stealing food from stores and rummaging through discarded lunch bags or trash cans to find partially eaten left-over food. Some parents find it necessary to lock the refrigerator and all cabinets containing food to prevent their daughter or son from excessive eating. Despite these precautions, youth with PWS often pry open locked cabinets to gain access to food. Adolescents with PWS may weigh 250 to 300 pounds by their late teens.
The Vanderbilt Kennedy Center for Research on Human Development is one of a network of national centers for research on mental retardation and other developmental disabilities. Its aims are to better understand human development, to prevent and solve developmental problems, and to enable persons with developmental disabilities to lead productive, independent lives.
Prader-Willi syndrome: correlates of compulsivity--National Institute of Child Health and Human Development (2002-2007)
Elisabeth Dykens, Ph.D., Principal Investigator
The Prader-Willi Syndrome Association
Prader-Willi syndrome - Health Library