What is Prader-Willi syndrome?
Prader-Willi syndrome (PWS) is a rare genetic condition that affects how the body grows and develops. It can cause weak muscle tone, learning difficulties, problems with hormone production and an overwhelming feeling of hunger that can lead to excessive weight gain.
PWS occurs when certain genes on chromosome 15, which should be active in the copy inherited from the father, do not work as expected. This usually happens because a small section of the father's chromosome is missing or because both copies of chromosome 15 have been inherited from the mother.
Less commonly, the genes are present but do not function correctly. These genetic changes affect the part of the brain that helps regulate hunger, growth and hormone production.
What is the prognosis of Prader-Willi syndrome?
Prader-Willi syndrome is a lifelong condition with no cure, but early diagnosis and appropriate care can improve quality of life and long-term health. Without effective management, excessive eating can lead to severe obesity, type 2 diabetes, cardiovascular disease and breathing difficulties.
With appropriate support, many people can maintain a healthier weight and live well into adulthood.
What are the symptoms of Prader-Willi syndrome?
Symptoms vary with age and may include:
- In infancy: weak muscle tone (hypotonia), poor sucking, feeding difficulties and delayed development.
- In childhood: persistent hunger, excessive food-seeking behaviour, delayed speech, learning difficulties and short stature.
- During adolescence and adulthood: delayed or incomplete puberty, reduced fertility, low muscle mass and behavioural difficulties, including anxiety, emotional outbursts and repetitive behaviours.
How is Prader-Willi syndrome diagnosed?
Diagnosis is confirmed through genetic testing, usually using a blood sample to identify the characteristic changes affecting chromosome 15. Testing may be recommended when a baby has marked muscle weakness or feeding difficulties, or when an older child shows excessive hunger, developmental delays or other characteristic features.
What causes Prader-Willi syndrome?
PWS is caused by the loss of activity of certain genes on chromosome 15 that should be active in the copy inherited from the father. The genetic change usually occurs by chance and is rarely inherited. Genetic counselling can help families understand the cause and the likelihood of the condition occurring in future pregnancies.
Can Prader-Willi syndrome be prevented?
Prader-Willi syndrome cannot generally be prevented because it usually results from a random genetic change. Genetic counselling may be appropriate for families who have a child with PWS or concerns about recurrence in future pregnancies.
What are the treatments for Prader-Willi syndrome?
Treatment focuses on managing symptoms, supporting development and preventing complications. A multidisciplinary team may recommend:
- Growth hormone therapy: can improve growth, body composition, muscle strength and physical function.
- Nutritional management: a balanced, calorie-controlled diet, structured mealtimes and secure food storage to help prevent excessive eating and obesity.
- Physical and developmental support: physiotherapy, speech and language therapy, occupational therapy and educational support.
- Behavioural and psychological support: structured routines and strategies to manage anxiety, emotional difficulties and food-related behaviours.
- Hormone replacement: treatment for deficiencies in sex hormones and delayed puberty, when appropriate.
- Treatment of associated conditions: management of sleep apnoea, scoliosis, undescended testicles and other complications as required.
Which specialist should you see for Prader-Willi syndrome?
A consultant paediatric endocrinologist should be involved early to assess growth, hormone function and suitability for growth hormone treatment. Ongoing care may involve a paediatrician, clinical geneticist, dietitian, physiotherapist, psychologist and other specialists according to the person's needs.
