Prader-Willi Syndrome (PWS)

Prader-Willi syndrome (PWS) is a rare, neurobehavioral condition that presents congenitally. PWS affects many different organs and systems of the body, including the heart, nervous system, musculoskeletal system, lungs, reproductive organs, and endocrine system (hormones).¹ 

Some of the first features that are noticeable during infancy include poor muscle tone, which causes a baby to appear “floppy,” and problems with sucking and feeding, which may contribute to poor growth and development. Many infants also have very small, underdeveloped sex organs. The symptoms of PWS vary widely in affected individuals and also vary over time.¹

Genetic Cause of PWS

PWS is caused by missing genetic material on chromosome 15. Normally, the father’s genes are expressed on chromosome 15, while the mother’s genes remain inactive.² PWS may develop as a result of the following changes or mutations to genes on chromosome 15¹:

• Missing (or deleted) copies of the father’s genes on chromosome 15
• Presence of 2 copies of the mother’s chromosome 15 genes and no copies from the father
• Defects or changes to the father’s genes on chromosome 15

Read more about PWS genetics

Early Interventional Treatment for PWS

Children with PWS greatly benefit from immediate and early interventions.¹ 

Dietary Restrictions

A careful supervision of diet and nutrition is critical to controlling weight gain and preventing obesity. A strict diet plan and limited access to food are required, and an exercise plan can complement this discipline and build muscle.¹

Limiting access to food and controlling weight will allow a child with PWS to live a healthier, more comfortable life.^1,3 Parents must lock refrigerators and cabinets in which food is stored to prevent unsupervised access. Alarms on locked storage spaces in the kitchen are meant to protect children with PWS, keeping them safe and preventing the following³:

• Binge eating, which may lead to death from choking or result in overexpansion and possible rupture of the stomach
• Rapid weight gain, which can lead to morbid obesity, obesity-related medical complications, and poor health
• Feelings of anxiety and guilt, which develop when the children are able to access food they know they should not be eating
• Distraction of food sources, which draws them away from beneficial activities, such as sleeping and exercising

Locks and alarms on kitchen cabinets and the refrigerator relieve parents of the need to be on constant guard to prevent access to food sources. It is also important that parents and other family members of children with PWS keep food out of sight to reduce temptation, frustration, anger, and distraction.³

Read more about PWS diet and nutrition

Growth Hormone Therapy

Growth hormone therapy is a primary treatment tool for PWS, with a strong record of safety and efficacy. Treatment can be started as soon as PWS is suspected, and can be initiated in patients as young as 3 months. This therapy not only improves linear growth but also improves muscle strength, psychomotor development, metabolic state, and cognitive function.⁴

Read more about somatropin

Physical and Social Therapies

Physical, occupational, and speech therapy help them build strength and reach developmental milestones, which are often delayed.¹ 

Behavioral therapy, social skills training, and mental health counseling are important interventions to manage some of the complex behavioral issues associated with PWS.¹

Read more about PWS treatment

Educational Interventions

Individualized Education Programs (IEPs) may be helpful in meeting the needs of children with PWS and in managing learning disabilities and behavioral problems that cannot be addressed in traditional educational environments.^1,5 

The parents of children with PWS must educate school staff and teachers about the behavioral characteristics and intellectual disabilities that may manifest during the school day. These can include generalized weakness, low arousal, day sleepiness, outbursts of emotion, stubbornness, obsessive-compulsive behaviors, and most importantly, aggressive food-seeking behaviors and insatiable appetite. Children with PWS must not have easy access to food in the school environment, including food served in cafeterias and food found in trash cans. Additional supervision of children with PWS is required during school mealtimes.⁵  

Children with PWS require a structured schedule and predictable routine, as unfamiliar routines or alterations in the daily schedule may prove emotionally stressful and result in outbursts of anger.⁵

Read more about PWS care team

Choking Prevention and Education

Given their compulsive consumption of food, individuals with PWS tend to rush while eating, eat large quantities of food all at once, or eat surreptitiously. This insatiable desire for food is often complicated by poor oral muscle control, related to overall decreased muscle tone (hypotonia).⁶ Hypotonia presents in patients with PWS as early as birth, causing a lack of coordination, motor control and strength, and effective swallowing (dysphagia).⁶ 

Additionally, individuals with PWS produce low quantities of saliva, which is not only sparse but very thick and sticky, making it even more difficult to digest and swallow food properly.^6,7 

These clinical features predispose individuals with PWS to choking, which can be fatal if mealtimes are not supervised. Caregivers of individuals with PWS must be trained in the management of life-threatening choking, including cardiopulmonary resuscitation (CPR) and the Heimlich maneuver.⁶ 

Measures to prevent choking include⁶:

• Cutting food into small pieces
• Avoiding foods that increase the risk of choking
• Scheduling careful meal supervision, including verbal instructions to eat slowly

Emergency Situations and PWS-Related Complications

Vomiting and abdominal pain are rare in individuals with PWS because of their decreased ability to vomit and their relatively high pain threshold. Caregivers and families should be aware of the rarity of these signs and symptoms so that if they do occur, they immediately seek emergency medical services.⁸ 

The symptoms of vomiting and abdominal pain may indicate acute gastric dilation, which may also be accompanied by anorexia nervosa, bulimia, gastric hemorrhage, binge eating, and acute pancreatitis. Acute gastric dilation can eventually lead to complications like stomach rupture. Vomiting and abdominal pain may be caused by an enlarged stomach that has ruptured or become necrotic (death of tissues) as a consequence of overeating.⁸ 

Other possible complications of PWS include type 2 diabetes, bone fractures due to osteoporosis/osteopenia, heart failure, sleep apnea, lung problems, hypertension, mild-to-moderate cognitive impairment, and behavioral problems. Individuals with food compulsion may require constant supervision due to life-threatening complications associated with severe obesity and cardiac insufficiency.^9,10

Read more about PWS complications

Support Groups and Organizations

Patients with PWS and their families and caregivers can find helpful educational information, PWS-related research, and community support by joining organizations such as the Prader-Willi Syndrome Association (www.pwsausa.org) and the Foundation for Prader-Willi Research (www.fpwr.org). 

References

1. Prader-Willi syndrome. Mount Sinai. Accessed July 27, 2023.
2. What causes Prader-Willi syndrome (PWS)? NIH – Eunice Kennedy Shriver National Institute of Child Health and Human Development. Accessed July 27, 2023.
3. Food security – locks and alarms. Prader-Willi Syndrome Association USA. Accessed July 27, 2023.
4. Szabadi S, Sila Z, Dewey J, Rowland D, Penugonda M, Ergun-Longmire B. A review of Prader–Willi syndrome. Endocrines. 2022; 3(2):329-348. doi.org/10.3390/endocrines3020027
5. Chedd N, Levine K, Wharton RH. Educational considerations for children with Prader-Willi syndrome. In: Greenberg LR, Alexander RC, eds. Management of Prader-Willi Syndrome. 2nd ed. New York, NY: Springer-Verlag; 1995:302-316. 
6. Brind’Amour K. Choking education an important element of care for Prader-Willi syndrome families. Pediatrics Nationwide. Published July 31, 2020. Accessed July 27, 2023.
7. Munné-Miralvés C, Brunet-Llobet L, Cahuana-Cárdenas A, Torné-Durán S, Miranda-Rius J, Rivera-Baró A. Oral disorders in children with Prader-Willi syndrome: a case control study. Orphanet J Rare Dis. 2020;15:43. doi:10.1186/s13023-020-1326-8
8. Stevenson DA, Heinemann J, Angulo M, et al. Gastric rupture and necrosis in Prader-Willi syndrome. J Pediatr Gastroenterol Nutr. 2007;45(2):272-274. doi:10.1097/MPG.0b013e31805b82b5
9. Prader-Willi syndrome. NORD. Updated July 12, 2023. Accessed July 27, 2023.
10. van Abswoude DH, Pellikaan K, Rosenberg AGW, et al. Bone health in adults with Prader-Willi syndrome: clinical recommendations based on a multicenter cohort study. J Clin Endocrinol Metab. 2022;108(1):59-84. doi:10.1210/clinem/dgac556

Reviewed by Debjyoti Talukdar, MD, on 7/29/2023.

---

Maria Arini Lopez, PT, DPT, CSCS, CMTPT, CIMT

Maria Arini Lopez, PT, DPT, CSCS, CMTPT, CIMT is a freelance medical writer and Doctor of Physical Therapy from Maryland. She has expertise in the therapeutic areas of orthopedics, neurology, chronic pain, gastrointestinal dysfunctions, and rare diseases especially Ehlers Danlos Syndrome.