Definition

Prader-Willi syndrome is a rare genetic disorder. It is characterized by:

  • Developmental delays
  • Insatiable appetite leading to obesity by age six
  • Mental disabilities
  • Incomplete sexual development
  • Short adult stature

Causes

Prader-Willi syndrome is believed to be caused by a genetic defect on chromosome 15, passed on by the father.

Genetic Material

Chromosome_DNA
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Risk Factors

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

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
  • Lethargy

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

Diagnosis

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

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.

Treatment:

  • Food restriction and supervision
  • Regular exercise

Behavior Issues

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:

Treatment:

  • Daily structure and routine
  • Firm rules
  • Rewards for good behavior
  • Psychotropic drugs may be necessary

Developmental Issues

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

Treatment:

For certain conditions, such as delayed physical growth or sexual development, growth hormone therapy may be helpful.

Related Health Conditions

The following conditions are associated with Prader-Willi syndrome and will require life-long management:

Prevention

There are no guidelines for preventing Prader-Willi syndrome.