Prader-Willi syndrome is a rare genetic condition that affects many body systems. It often results in obesity and mild to moderate cognitive disability. The genetic change that causes PWS occurs at random when the baby is in the womb. Infants with PWS typically have low muscle tone (the muscles have less than normal resistance to movement), growth problems, and trouble sucking or feeding. They also experience delays reaching developmental milestones, such as walking, talking, learning new things, and social skills. A defining feature of PWS is an appetite that the child cannot satisfy. This desire to eat more often develops between ages 3 and 8 years and results in major weight gain. People with PWS often have behavior problems, such as anxiety and compulsive habits, like picking at their skin. In the United States, PWS affects about 1 in 16,000 to 20,000 live births. It affects people of all genders and ethnic backgrounds worldwide.

Physical therapists work with children who have PWS and their families to address physical, mental, and behavioral challenges. Children with PWS may see a physical therapist to help improve their balance, strength, coordination, and endurance.

Physical therapists are movement experts. They improve quality of life through hands-on care, patient education, and prescribed movement. You can see a physical therapist directly for evaluation and treatment without a physician’s referral.* To find a physical therapist in your area, visit Find a PT.

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*A referral may still be required by your insurance policy, corporate policies, or state practice laws (some states limit the type of treatment or number of visits without a referral).

On this page

• What Is Prader-Willi Syndrome?
• Signs and Symptoms
• How Is It Diagnosed?
• How Can a Physical Therapist Help?
• Can This Injury or Condition Be Prevented?
• What Kind of Physical Therapist Do I Need?

What Is Prader-Willi Syndrome?

Prader-Willi syndrome is a genetic disorder first described in 1956. A defective or missing gene causes the disorder, which occurs randomly. The severity of symptoms varies from person to person.

With careful weight management strategies and a good support system, people with PWS can remain healthy and live a normal lifespan. But related obesity can lead to:

• Problems breathing
• Diabetes
• High blood pressure
• Heart disease
• Sleep apnea (breathing stops and starts)
• Atherosclerosis (buildup of fatty material in the arteries)
• Early death

People with PWS have the best chance for managing their weight successfully and an increasing lifespan with:

• Healthy diet and nutritional education
• Controlled access to food
• Growth hormone treatment
• Exercise programs
• Early diagnosis, especially in the newborn period

Signs and Symptoms

The severity of symptoms of PWS varies widely from person to person. People with PWS have distinct facial and body features, including:

• Almond-shaped eyes
• Short height with small hands and feet
• A downturned mouth
• Lighter hair color and fairer skin than their family members

They may also have sleep problems with excessive daytime sleepiness, decreased reaction to pain, and behavior problems.

PWS has two stages.

First Stage: Birth to About 2 Years

The first stage of PWS is marked by:

• Hypotonia (low muscle tone)
• Developmental delays
• Feeding problems due to difficulty sucking and using the mouth muscles

Second Stage: Between 1 and 4 Years and Into Adulthood

In the second stage of PWS, children develop hunger they can't satisfy (called hyperphagia). This type of hunger often begins between 3 and 8 years and leads to rapid weight gain. Children with PWS never feel full. They have a constant need to eat and find food. In fact, however, people with PWS need less food per day to meet their caloric needs than those without it.

Other symptoms that may occur during Stage 2 include:

• Hypotonia (low muscle tone)
• Hip dysplasia (problems with the formation of the hip joint)
• Osteoporosis (low bone mass)
• Short height (due to growth-hormone deficiency), with small hands and feet
• Problems breathing when sleeping (such as sleep apnea)
• Absent or incomplete puberty
• Behavior problems, including anxiety, obsessive-compulsive symptoms, impulse control, and skin picking
• Learning problems
• Scoliosis (curvature of the spine)
• Vision problems
• Lack of response to pain, which can mask other symptoms

How Is It Diagnosed?

Medical doctors diagnose PWS based on traits reported by a family member, another caregiver, or a physical therapist or noted by the doctor during a checkup. Newborns and infants with PWS always have low muscle tone. Infants who have problems feeding or who are failing to thrive will need further testing. Health care providers consider PWS in any infant born with unexplained low muscle tone. A doctor-ordered blood test, which detects 99% of cases, can confirm the diagnosis. Early diagnosis can improve quality of life. Your child may have a team of health professionals, including a physical therapist, to help.

How Can a Physical Therapist Help?

Your physical therapist will serve as a valuable partner to help your child reach their potential. Physical therapists play an important role in the overall medical management of PWS. Managing PWS includes:

• Proper diet
• Exercise
• Growth hormone treatments
• Strategies to address behavior and learning problems

Physical therapists may provide treatment services in the home, at school, or in an outpatient clinic. The goal of physical therapy is to improve strength, endurance, coordination, and movement. Your physical therapist will focus on different goals at each stage of your child's life to help them take part in family, school, and community activities.

Your physical therapist will perform an evaluation that includes:

• Parental concerns. Your physical therapist will ask about your concerns and goals for your child.
• Birth and developmental history. Your physical therapist will ask about your child's birth, hospital treatment, and motor development. Motor development includes skills, such as head control, rolling, sitting on their own, crawling, and walking.
• Medical history/health and behavioral concerns. Your physical therapist will ask about other medical conditions your child may have. They also will ask questions to learn what a typical day looks like for your child.
• Physical exam. Your physical therapist will do a physical exam to identify your child's abilities. This includes examining strength, muscle tone, endurance, and developmental milestones.
• Your physical therapist will work with other members of your child's health care team. They also will coordinate care to ensure that your child's needs and goals are addressed in the safest, most effective way possible.

Physical Therapy in the Early Years: Birth to Age 4

Physical therapists educate parents about their infant's condition. They teach activities parents can do with their child to promote movement and muscle strength. Children at this age learn through play. Your physical therapist will develop a fun, play-focused treatment plan. It will be based on your child's specific strengths and weaknesses. They will also address your goals and help you to include these activities in your daily family routines. Most infants 6 months and younger need help feeding. Some infants may need specialized nipples, feeding tubes, and specific feeding positions.

Physical Therapy in the School Years: Ages 5 to 17

As children with PWS age, they often will struggle with obesity and inactivity. Exercise can help throughout your child’s life to protect against muscle loss, maintain bone strength, and manage weight. Your physical therapist may suggest a fitness program or provide strategies to promote physical activity and improve fitness. Regular physical activity in children with PWS increases lean body mass and makes bones stronger. Some children with PWS may receive human growth hormone, or rhGH, therapy from their doctor. rhGH combined with physical activity has the greatest benefits. Scoliosis is also common in children with PWS. This condition may be partially managed with physical therapy.

Physical Therapy Into Adulthood: Age 18+

For adults with PWS, inactivity and obesity-related health issues can result in:

• Decreased mobility
• Less independence
• Decreased participation in typical activities at home and in their community

Up to 25% of adults with PWS develop Type 2 diabetes. A physical therapist can continue to provide an exercise program and targeted training to help adults with PWS:

• Improve daily activity.
• Keep and improve overall mobility.
• Sustain quality of life.
• Get access to devices to assist with walking and moving later in life.

Can This Injury or Condition Be Prevented?

Because the genetic change that causes PWS happens at random when the baby is developing in the womb, there is no way to prevent it. Expectant mothers may get genetic testing during pregnancy if there is concern for a genetic disorder.

PWS affects many aspects of health. Improvements in care mean many people with PWS can now live a full lifespan. Physical therapists and other health care providers can help lessen some of the effects of the syndrome, including obesity and a potential inactive lifestyle.

What Kind of Physical Therapist Do I Need?

Every physical therapist is trained by education and practical experience to treat a wide variety of conditions and injuries. Some things to consider as you choose a physical therapist for people with PWS include:

• A physical therapist who focuses on treating infants and children.
• A physical therapist with experience treating obesity and its associated chronic health conditions.
• A physical therapist who is a board-certified clinical specialist or who has completed a residency or fellowship in pediatric physical therapy. This physical therapist will have clinical expertise, knowledge, and experience that may apply to developmental conditions such as PWS.

You can find physical therapists in your area with these credentials and clinical expertise on Find a PT, a tool built by the American Physical Therapy Association.

General tips when you are searching for a physical therapist (or any health care provider):

• Ask family, friends, or other health care providers for recommendations.
• When you contact a physical therapy clinic or agency, ask about the physical therapists' experience in treating children with PWS, or other developmental or genetic conditions.
• Be prepared to describe your child's symptoms and motor skills in as much detail as possible during your first visit.

The APTA Academy of Pediatric Physical Therapy contributed to this consumer resource. It is for informational purposes only and is not intended to represent the position of APTA Pediatrics.