Prader-Willi Syndrome Symptoms and Treatment

Prader-Willi syndrome is caused by a genetic disorder of chromosome 15. It is a rare disorder present at birth that results in a number of physical, mental, and behavioral problems. A key feature of Prader-Willi syndrome is a constant sense of hunger that usually begins at about 2 years of age.

Girl with head back holding cereal bowl to her mouth
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People with Prader-Willi syndrome want to eat constantly because they never feel full (hyperphagia) and usually have trouble controlling their weight. Many complications of Prader-Willi syndrome are due to obesity.

If you or your child has Prader-Willi syndrome, a team of specialists can work with you to manage symptoms, reduce the risk of developing complications, and improve quality of life.

Prader-Willi occurs in approximately one of every 12,000-15,000 people, in both boys and girls, and in people of all ethnic backgrounds. Prader-Willi syndrome is usually diagnosed by the appearance and behaviors of a child, then confirmed by specialized genetic testing of a blood sample. Although rare, Prader-Willi syndrome is the most common genetic cause of obesity.

Symptoms of Prader-Willi Syndrome

At first, an infant with Prader-Willi syndrome will have trouble growing and gaining weight (failure to thrive). Because of weak muscles (hypotonia), the infant is not able to drink from a bottle and may need special feeding techniques or tube feedings until his/her muscles become stronger. Infants with Prader-Willi syndrome are often behind other children in development.

Between ages 1-6 years the child with Prader-Willi syndrome suddenly develops a tremendous interest in food and starts overeating. It is believed that the child with Prader-Willi never feels full after eating, and may actually go on eating binges. Parents of children with the syndrome often have to lock the kitchen cabinets and refrigerator to restrict the child's access to food. Children gain weight rapidly at this age.

Rate of Growth Slows

In addition to overeating, the child with Prader-Willi stops growing at an abnormal rate, and therefore are shorter than their peers for age and sex. The growth hormone insufficiency is also in part responsible for the change in body composition and increase in amount of fat.

Children with Prader-Willi syndrome have endocrine problems including reduced or absent secretion of sex hormones (hypogonadism) and delayed or incomplete sexual development. Children with the syndrome may also have mild to moderate mental retardation or learning problems and may have behavior problems such as obsession, compulsion, stubbornness, and temper tantrums.

Distinctive Facial Features

Distinctive facial features also identify a child with Prader-Willi syndrome. These include a narrow face, almond-shaped eyes, small-appearing mouth, a thin upper lip with downturned corners of the mouth, and full cheeks. The child's eyes may cross (strabismus).

Treatment of Prader-Willi Syndrome

There is no cure for Prader-Willi syndrome. However, the physical problems caused by the syndrome can be managed. During infancy, special feeding techniques and formulas can help the infant grow. Physical therapy and exercise help improve strength and coordination. Administering human growth hormone (Genotropin, Humatrope, Norditropin) improves muscle mass and growth. Also, sex hormone therapy can be given. Both to treat males with underdevelopment of the testes, and at the time of puberty to stimulate secondary sexual development (for self-esteem and bone density benefit).

Speech therapy can help children who are behind in their language skills to catch up to their peers. Special education services and supports help children with Prader-Willi achieve their full capacity.

As the child grows, eating and weight problems can be controlled through a balanced, low-calorie diet, weight monitoring, external food restriction, and daily exercise.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Genetics Home Reference. Prader-Willi syndrome.

  2. Prader-Willi Syndrome Association (USA). PWS basic facts.

  3. National Health Services. Prader-Willi syndrome.

  4. National Organization of Rare Disorders. Prader-Willi syndrome.

  5. Eunice Kennedy Shriver National Institute of Child Health and Human Development. What are the symptoms of Prader-Willi syndrome (PWS)?

  6. Prader-Willi California Foundation. For therapists: speech and language therapists.

Additional Reading
  • Mayo Clinic. Prader-Willi Syndrome
  • National Organization for Rare Disorders. Prader-Willi Syndrome.
  • Prader-Willi Syndrome Association (USA). Frequently Asked Questions About Prader-Willi Syndrome.
  • Scheimann, A. (2006). Prader-Willi Syndrome. eMedicine. 

By Mary Kugler, RN
Mary Kugler, RN, is a pediatric nurse whose specialty is caring for children with long-term or severe medical problems.