Prader-Willi syndrome is a disease that is present from birth (congenital). It affects many parts of the body. People with this condition feel hungry all the time and become obese. They also have poor muscle tone, reduced mental ability, and underdeveloped sex organs.
Prader-Willi syndrome is caused by a missing gene on chromosome 15. Normally, parents each pass down a copy of this chromosome. The defect can occur in a couple of ways:
- The father's genes are missing on chromosome 15
- There are defects or problems with the father’s genes on chromosome 15
- There are two copies of the mother's chromosome 15 and none from the father
These genetic changes occur randomly. Persons who have this syndrome usually do not have a family history of the condition.
Signs of Prader-Willi syndrome may be seen at birth.
- Newborns are often small and floppy
- Male infants may have undescended testicles
Other symptoms may include:
- Trouble feeding as an infant, with poor weight gain
- Almond-shaped eyes
- Delayed motor development
- Narrowed head at the temples
- Rapid weight gain
- Short stature
- Slow mental development
- Very small hands and feet in comparison to the child's body
Children have an intense craving for food. They will do almost anything to get food, including hording. This can result in rapid weight gain and morbid obesity. Morbid obesity may lead to:
Exams and Tests
Genetic testing is available to test children for Prader-Willi syndrome.
As the child grows older, lab tests may show signs of morbid obesity, such as:
- Abnormal glucose tolerance
- High insulin level in the blood
- Low oxygen level in the blood
Children with this syndrome may not respond to luteinizing hormone releasing factor. This is a sign that their sex organs are not producing hormones. There also may be signs of right-sided heart failure and knee and hip problems.
Obesity is the greatest threat to health. Limiting calories will control weight gain. It’s also important to control a child’s environment to prevent access to food. The child’s family, neighbors, and school must work together, because the child will try to get food wherever possible. Exercise can help a child with Prader-Willi syndrome gain muscle.
Growth hormone is used to treat Prader-Willi syndrome. It can help:
- Build strength and agility
- Improve height
- Increase muscle mass and decrease body fat
- Improve weight distribution
- Increase stamina
- Increase bone density
Taking growth hormone therapy may lead to sleep apnea. A child who takes hormone therapy needs to be monitored for sleep apnea.
Low levels of sex hormones may be corrected at puberty with hormone replacement.
Mental health and behavioral counseling are also important. This can help with common problems such as skin picking and compulsive behaviors. Sometimes, medicine may be needed.
The following organizations can provide resources and support:
- Prader-Willi Syndrome Association:
- Prader Willi California Foundation:
- Foundation for Prader Willi Research:
The child will need the right education for their IQ level. The child will also need speech, physical, and occupational therapy as early as possible. Controlling weight will allow for a much more comfortable and healthy life.
Complications of Prader-Willi can include:
- Type 2 diabetes
- Right-sided heart failure
- Bone (orthopedic) problems
When to Contact a Medical Professional
Call your health care provider if your child has symptoms of this condition. The disorder is frequently suspected at birth.
Cooke DW, Divall SA, Radovick S. Normal and aberrant growth in children. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 13th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 24.
McCandless SE; Committee on Genetics. Clinical report - health supervision for children with Prader-Willi syndrome. Pediatrics. 2011;127(1):195-204. PMID: 21187304
Last reviewed on: 4/19/2016
Reviewed by: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.