Prader-Willi syndrome is a rare genetic disorder. It is characterized by:
- Developmental delays
- Insatiable appetite leading to obesity
Prader-Willi syndrome is believed to be caused by a genetic defect on chromosome 15, passed on by the father.
A risk factor is something that increases your chance of getting a disease or condition. Since Prader-Willi syndrome is caused by a random genetic defect, there are no known risk factors. However, in about 1% of cases, this defect may recur in the same family. Some genetic counselors recommend testing of affected children to identify very rare situations where the risk of recurrence might be 50%.
Symptoms of an infant born with Prader-Willi syndrome may include:
- Poor muscle tone
- Poor reflexes
- Small to normal size
- Inability to suck well
- A weak, squeaky cry
As a toddler, new symptoms may include:
- Delay of normal development, such as language skills and walking
- Behavior problems, such as temper tantrums and stubbornness
As the child gets older, symptoms may include:
- Insatiable hunger, resulting in compulsive eating and often obesity
- Continuing behavior problems, such as anger and inflexibility
- Learning disabilities
- Low to normal IQ
- Incomplete sexual development, and infertility as an adult
- High threshold for pain
- Insensitivity to temperature extremes
The diagnosis is usually evident shortly after birth based on symptoms and a characteristic physical appearance:
- Almond-shaped eyes
- Strabismus (misalignment of the eyes)
- Thin upper lip
- Narrow forehead
- Down-turned mouth
- Lighter coloring compared with other family members
Diagnosis can be confirmed by genetic testing of a blood sample.
Treatment, which continues into adulthood, is managed by the parents or caregivers of children with Prader-Willi syndrome. Key areas include:
Appetite and Weight
Perhaps the most important concern is managing food intake. People with Prader-Willi syndrome are unable to resist food. This is due to a defect in the part of the brain that controls the normal feelings of fullness when the body has had enough food. In addition, people with Prader-Willi syndrome have a slow metabolism. These traits can cause excessive weight gain, morbid obesity, and other related health problems. Research into the use of novel anti-obesity medications is underway.
- Food restriction and supervision
- Regular exercise
Infants and young children with Prader-Willi syndrome are typically happy and loving. But as they get older, you may notice behavior changes. Common behaviors include:
- Temper tantrums
- Difficulty with transitions
- Mood swings
- Obsessive-compulsive habits
- Daily structure and routine
- Firm rules
- Rewards for good behavior
- Psychotropic drugs may be necessary
Children with Prader-Willi syndrome may experience the following:
- Delay in motor skill development
- Cognitive delay or limits
- Delays in physical growth
- Incomplete sexual development in adolescence
For certain conditions, such as delayed physical growth or sexual development, growth hormone therapy may be helpful.
March of Dimes
Prader-Willi Syndrome Association (USA)
Foundation for Prader-Willi Research
The Hospital for SICK Kids
Missouri Developmental Disability Resource Center website. Available at: http://www.moddrc.org/ .
Smith’s Recognizable Patterns of Human Malformation . 6th Edition. Elsevier Saunders, 2006.
Wattendorf DJ, Muenke M. Prader-Willi syndrome. Am Fam Physician . 2005; 72(5):827-830.
Last reviewed November 2008 by
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