Prader-Willi Syndrome (PWS)

Prader-Willi syndrome (PWS) is a rare genetic disorder that occurs in one out of every 15,000 births. It affects both males and females. In Belgium and Luxemburg, 4-5 children are born with PWS every year. PWS is a spectrum disorder and symptoms vary in severity and frequency. 

The symptoms of Prader-Willi syndrome are most likely due to the dysfunction of a portion of the brain called the hypothalamus.  

PWS is caused by a lack of active genetic material in a particular region of chromosome 15 (15q11-q13). Normally, individuals get one chromosome 15 from the mother and one from the father. The genes in the 15q11-q13 region only function when they come from the father. In PWS, a genetic defect causes the inactivity of chromosome 15 from the father (paternal chromosome 15).  

These genetic problems almost always (98%) occur sporadically: this means that they are not present in one of the parents. The chance that this will happen again in the next child is therefore very low, except in specific cases. It is therefore wise to discuss this risk of recurrence with a clinical geneticist. 

A suspected diagnosis of Prader-Willi syndrome is usually put forth by a physician based on clinical symptoms. The diagnosis is then confirmed by a blood test analysed in the genetic laboratory. 

It is characterised by muscle weakness, feeding difficulties during the first years of life followed by obsessive eating and obesity from the age of 4 years, short stature, underdevelopment of the genital organs, mental retardation and behavioural problems. 

There is currently no treatment that can eliminate all symptoms of PWS. The different aspects must therefore be tackled separately. 

A multidisciplinary approach (doctors, nurses, physiotherapists, occupational therapists, speech therapists, dieticians) is highly recommended and can substantially improve the psychomotor development of patients and prevent obesity. 

Growth hormone therapy can help improve muscle weakness and body composition.