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Prader-Willi syndrome

Prader-Willi Syndrome – Facts and Information

Information provided by Thomas C. Weiss - Published: 2010-02-07

Prader-Willi Syndrome (PWS) involves a disorder of chromosome 15. The disorder affects approximately one out of every twelve to fifteen thousand people from both sexes and all races.

The major characteristics of the disorder include hypotonia, hypogonadism, hyperphagia, cognitive impairment, and difficult behaviors. One of the major medical concerns associated with PWS is morbid obesity.

Defining Prader-Willi Syndrome

While the cause of PWS is complex, the disorder is the most common known genetic cause of life-threatening obesity in children. PWS commonly causes low muscle tone, incomplete sexual development, short stature when not treated with growth hormone, as well as a chronic sense of hunger which, coupled with a metabolism that utilizes far fewer calories than is common, may lead to excessive consumption of food and life-threatening obesity. The compulsion to consume food makes consistent supervision a necessity. The person’s average I.Q. is around seventy, although people with I.Q.’s considered, ‘normal,’ nearly always have learning issues. People with PWS also experience motor and social deficits.


At birth, people with PWS usually have a low birth weight, weak muscles – also referred to as, ‘hypotonia,’ and experience difficulty sucking due to the presence of hypotonia, which can lead to a diagnosis of failure to thrive. Children with PWS move into a second stage of, ‘thriving too well,’ which typically has an onset between the ages of two and five years, although it may occur later. An extreme and unsatisfied drive to consume food, also referred to as, ‘hyperphagia,’ lasts throughout the person’s lifetime. Children with PWS usually have very sweet and loving personalities, yet this phase is also characterized by increased appetite, weight control issues, motor delays, as well as some behavioral issues and unique medical issues.

Causes and Diagnosis of Prader-Willi Syndrome (PWS)

The cause of PWS is genetic, from a loss of genes that are usually contributed by the child’s father, which remain unidentified at this time. What is known is that PWS occurs from three main genetic errors. Approximately seventy-percent of people with the disorder have a non-inherited deletion in the paternally-contributed chromosome 15. Around twenty-five percent have maternal uniparental disomy (UPD), or two maternal 15 and no paternal chromosome 15. Two-to-five percent of people with PWS have an error in the, ‘imprinting,’ process, which renders the paternal contribution non-functional.

Genetic testing is the preferred means of diagnosing PWS. DNA methylation analysis can confirm a diagnosis of the disorder. ‘FISH,’ and DNA techniques may identify the particular gene cause ad associated risk of recurrence. People who have received test results that are either negative or inconclusive should be re-tested. The risk of recurrence is significant only in rare cases with imprinting mutations, inversions, or translocations. Families that have PWS should receive genetic counseling.

Prader-Willi Syndrome – Concerns

There are a number of concerns associated with Prader-Willi Syndrome (PWS). These concerns are related to areas such as weight, behavior, developmental concerns, and additional concerns. What follows are descriptions of some of these concerns.

Appetite Disorder: The cause of a person with PWS’ disordered appetite function is thought to be hypothalamic dysfunction. Obsession with food and compulsive eating commonly start before the person reaches age six. The urge to eat is both overwhelming and physiological, they experience difficulties with controlling this urge and require constant vigilance.

Weight Management Challenge: Adding to the stress of an excessive appetite is the fact that people with PWS use less calories that people without the disorder, commonly between 1,000 and 1,200 kcal per day for adults, because of low muscle mass and inactivity. Doctors often recommend a balanced and low-calorie diet that includes vitamin and calcium supplements for people with PWS, as well as regular weight checks and periodic diet reviews. Due to a tendency to binge, weight control depends on external food restriction and could require locking the kitchen and food storage areas. Daily exercise is also recommended for people with PWS.

Behavior Issues: While infants and young children with PWS are usually loving and happy, exhibiting few behavior problems, older children and adults with PWS may experience difficulties with behavior regulation. Older children and adults with PWS may manifest difficulties with transitions and unanticipated changes. The onset of behavioral symptoms commonly coincide with theonset of hyperphagia, although not all behaviors are food-related. Difficulties often peak while the person is in adolescence or early adulthood. Establishment of daily routines, structure, firm rules and limits – as well as, ‘time-outs,’ and positive rewards work best for management of behaviors.

Psychotropic medications such as serotonin reuptake inhibitors may be beneficial in treating obsessive-compulsive disorder symptoms, perseveration, and mood swings. While depression is common among adults with PWS, psychotic episodes are rare.

Motor Skills: Milestones in motor development are usually delayed in children with PWS by one to two years, although hypotonia improves. Children with PWS may continue to experience deficits in coordination, strength, balance, and motor planning. Physical and occupational therapies can assist in the promotion of skills development and proper functioning. Children with the disorder may require growth hormone treatment. Exercise and sports activities should be encouraged, with adaptations being made as needed.

Oral Motor and Speech: The presence of hypotonia can create problems with feeding in children with PWS, as well as delayed speech and poor oral-motor skills. Children with the disorder may require speech therapy and should be assessed in infancy. Picture communication and sign language may be used in order to reduce frustration and assist communication efforts. Products that enhance the production of saliva can help with articulation problems. Training in social skills may improve a child with PWS’ pragmatic language use. Despite delays verbal abilities often become an area of strength for children with PWS.

Cognition: People with PWS have I.Q.’s that range between 40 and 105, with an average of 70. People with PWS who have, ‘normal,’ I.Q.’s may still experience learning disabilities. Problem areas can include short-term auditory memory, attention, and abstract thinking. Typical strengths among persons with PWS include long-term memory, receptive language, and reading abilities. Early infant stimulation is something that should be encouraged. The need for special education services and supports is something that should be assessed in preschool and beyond.

Growth: A diagnosis of failure to thrive while a child with PWS is in infancy may require tube feeding. Infants need to be monitored closely to ensure they receive an adequate amount of calories and gain weight appropriately. Growth hormone is usually deficient causing short stature, high body fat ratio, and lack of pubertal growth spurt – even in people with PWS who have an average weight. The need for growth hormone therapy is something that should be assessed in both children and adults with PWS.

Sexual Development: Sex hormone levels in people with PWS, both testosterone and estrogen, are commonly low. The presence of,‘Cryptochidism,’ in male infants might require surgery. Children of both genders have good responses to treatment for hormone deficiencies, although side effects have been reported. The appearance of pubic hair at an early age is common, although the onset of puberty is usually late and incomplete.

Other Common Concerns

* Scoliosis
* Strabismus
* Sleep apnea
* Osteoporosis
* Skin picking
* Hypertension
* Dental problems
* Hypoventilation
* Sleep disturbances
* Daytime sleepiness
* Nighttime enuresis
* Stasis ulcers, cellulitis
* Right-sided heart failure
* Skin problems in fat folds
* Diabetes mellitus, type II
* Hypoventilation and desaturation

People with PWS usually experience general good health. If their weight is controlled, their life expectancy may be average, and their health and functioning can be maximized. The constant need to restrict food and manage behavior can be stressful for family members. Family counseling may be needed. Both adolescents and adults with PWS can function well in supported living programs and group environments if the needed diet control and structures are provided. Employment through sheltered workshops and other forms of highly-structured and supervised settings is successful for many people with PWS.

Citation: Disabled World News (2010-02-07) – Prader-Willi Syndrome (PWS) affects approximately one out of every twelve to fifteen thousand people from both sexes and all races.

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