Prader-Willi Syndrome

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Prader-Willi syndrome is a congenital (present at birth) disease. It affects many parts of the body. A key feature of this syndrome is the person wants to eat all the time and usually has trouble with weight. Many other problems with this condition include reduced muscle tone and mental ability, and sex glands that produce little or no hormones.

This syndrome is caused by a missing gene on chromosome 15. Normally, your parents each pass down a copy of this chromosome. Most patients with Prader-Willi are missing the genetic material from the father’s chromosome. Patients with this condition often have two copies of the mother’s chromosome 15.


Signs and symptoms usually occur in two stages.

Signs that may be present in the first year of life include:

  • Poor muscle tone. Infants may feel “floppy” when held.
  • Distinct facial features including:
    • Almond-shaped eyes
    • Narrow head at the temple
    • Turned-down mouth
    • Thin upper lip.
  • Failure to thrive. Infants may have poor sucking reflex because of poor muscle tone.
  • Lack of eye coordination. Eyes may not move together so they may cross or wander to the side.
  • Poor responsiveness. A baby may seem unusually tired, respond poorly to stimulation, wake with difficulty or have a weak cry.

Signs from about 1-4 years of age include:

  • Food craving and weight gain. Child is always hungry, eats frequently and eats a lot. Unusual food-seeking behaviors such a hoarding food, eating things like garbage or frozen food.
  • Underdeveloped sex organs.
  • Poor growth and physical development. They may have short hands and feet, and are usually shorter than other family members.
  • Learning disabilities.
  • Delayed motor development. Sitting up may be delayed until 12 months and walking 24 months.
  • Speech problems.
  • Behavior problems. At times may be very stubborn or throw temper tantrums, have obsessive-compulsive disorder, or other mental health disorders.
  • Sleep disorders.
  • Scoliosis.
  • Nearsighted.
  • Light skin compared to other family members.
  • High pain tolerance.

Tests and Diagnosis

In infants, signs that may be a reason for the doctor to request a blood test include:

  • Poor muscle tone
  • Almond-shaped eyes
  • Narrowing of the head at the temple

In older children, the doctor may request a blood test if your child has weight gain or behavior problems.

Treatment and drugs

Most children will need the following care:

  • Good infant nutrition
  • Growth hormone treatment
  • Sex hormone treatment
  • A healthy diet
  • A range of therapies including physical therapy, speech therapies and developmental therapy.
  • Mental health care.

Home care

Tips to care for your child with Prader-Willi syndrome:

  • Carefully pick up the child because of their poor muscle tone.
  • Help prevent binge eating. Avoid purchasing high-calorie snacks; store food out of childs reach; lock areas where you store food; use small dishes when serving food so it will appear like a larger portion is being served.
  • Give supplemental vitamins or minerals if the child is on a restricted calorie diet.
  • Schedule the appropriate screening tests for complications of Prader-Willi syndrome such as diabetes, osteoporosis, and an abnormally curved spine (scoliosis).