Prader-Willi Syndrome: a complex condition caused by a chromosomal imbalance

Fat baby

PWS is a genetic condition which affects many parts of the body. It’s challenging for the young person with PWS and their families. Currently, there is no cure.

A complex genetic disorder, Prader-Willi syndrome (PWS) affects appetite, growth, metabolism, cognitive function and behaviour. Globally, an estimated one in 15 000 people have PWS.[i] It is recognised as the most common genetic cause of life-threatening childhood obesity. There is no known cause. Like all syndromes, PWS is not a disease and cannot be cured; it is present from birth, can occur in any family, affects all genders and races, and cannot be prevented.

PWS is caused by a lack of active genetic material in chromosome 15.[ii] This leads to dysfunction in the hypothalamus — which contains cells that regulate hunger and satiety — and other regions of the brain.[iii]  While the problem is not yet fully understood, it is apparent that people with this condition never feel full; they have a continuous urge to eat that they cannot learn to control. To compound this problem, people with PWS need less food than their peers without the syndrome because their bodies have less muscle and tend to burn fewer calories.[iv]

fat black babyPWS is typically characterised by low muscle tone (hypotonia), short stature (when not treated with growth hormone), incomplete sexual development, cognitive disabilities, behavioural problems, and the hallmark characteristics – chronic feelings of insatiable hunger and a slowed metabolism that can lead to excessive eating and life-threatening obesity if appetite is not controlled.[v]

According to Dr Engela Honey, a paediatrician based at the department of genetics at the University of Pretoria (UP), PWS is relatively rare compared to Down syndrome, for example, and the features in the neonate are also not as distinctive as Down syndrome. It is therefore often missed. “The most important reason for the non-diagnosis of PWS is the lack of awareness and the fact that doctors and other medical health professionals don’t know about the syndrome,” she says.

Early diagnosis and management make all the difference

All over the world researchers work hard to understand the extremely complex nature of this disorder. However valuable these efforts may be, it is the management of the syndrome that is of vital importance, Honey stresses. Those who have PWS need intervention and strict external controls, sometimes including padlocking access to food, to maintain normal weight and to help save their lives.

Janet Legemaate, whose son Luke has PWS, recalls that it took two years and eight months to receive a correct diagnosis. “Our son showed all the symptoms of PWS at birth. He was very floppy, non-responsive and unable to suckle. He was tested for almost every possibility, and then we had a chance discussion with a friend who had a child in her class with PWS. Our son had a FISH test, to detect any genetic abnormalities, but it came back negative. At age two, Luke started to pick up weight; we had a DNA methylation analysis done and we finally got the definitive diagnosis. He started growth hormone therapy three months later.”

Diagnosis of PWS is based on clinical suspicion and further genetic testing to confirm, says Honey. “The DNA methylation test for PWS detects 99% of cases. Given that early diagnosis, along with appropriate food security and early stimulation, helps to improve in the long term many of the symptoms and signs of PWS – such as constant food seeking and obesity as well as the delay in development and learning problems – this is a crucial test.”

A multi-disciplinary approach is important

PWS A5 flyer BackHoney advises that a multidisciplinary approach, including a paediatrician, a psychologist, an endocrinologist, a dietician, and occupational-, physio- and speech therapists, is key to helping parents cope.

Senior clinical psychologist, Molelekeng Sethuntsa adds that caring for a person with PWS can be time-consuming, and physically and emotionally exhausting, which is why it’s important for the caregiver to have adequate support systems.

“The most challenging behaviours observed in people with PWS are stress and change-related temper tantrums, food seeking, stealing associated with food, stubbornness, manipulation, skin-picking and lying,” says Sethuntsa. “Some may express all of these behaviours, while others will display only a few. In each case, professional support can help with overall management of PWS, including the improvement of school, social and psychological functioning.”

She advises parents of children with PWS to obtain information from the treating healthcare professionals so that they can learn more about management of the syndrome, and also feel that they are involved in the care and treatment plan for the patient.

It is important to always remember that behind the syndrome, there is a sensitive human being, a person in his or her own right with an individual personality and a complex emotional life, who deserves to be accepted by the community for what he or she is.

“Many parents of children with special needs find that family and friends are unwilling to try to understand the seriousness of the child’s condition, making it even more difficult to navigate the path we are on,” says Legemaate. “We have lost friends because our son is our priority. However, as a result, he is presently doing exceptionally well in many areas, including academically. Physically, he battles terribly to do what other youngsters his age do, but our work on that is ongoing.”

Her advice to parents of children with PWS? “After our initial devastation, we decided to do our best to help Luke reach his full potential. We did not do or allow anything that we would need to change later and that could cause stresses for Luke. We pre-empted situations that could have become uncomfortable or dangerous. Also, it is important to make time for yourself and your spouse. You have to build a mutual support system to help you as the years go by, and to give you that little respite, especially if your child is more severely affected by PWS.”

Looking to the future

prader willi syndrome

There is constant ongoing research on the management of PWS and the prevention of obesity. “The positive role of growth hormone replacement has been a major breakthrough and the administration of growth hormone is now becoming standard practice in children,” says Honey. “It is unfortunately costly and therefore not available to all patients. Drugs such as Oxytocin to suppress appetite have been the scope of much research.”

If you suspect your child may have a genetic disorder, contact your nearest health facility and ask the doctor to examine the child and do appropriate genetic testing.

[i] Rare obesity syndrome therapeutic target identified. Columbia University Medical Center. ScienceDaily. (Internet). 2017 March 13. Available from:
[ii] Questions & Answers on Prader-Willi Syndrome. The Foundation for Prader-Willi Research. Internet. 2017 March 13. Available from:
[iii] PWS Basic Facts. Prader-Willi Syndrome Association (USA). 2017 March 13. Available from
[iv] PWS Basic Facts. Prader-Willi Syndrome Association (USA). 2017 March 13.Available from:
[v] PWS Basic Facts. Prader-Willi Syndrome Association (USA). 2017 March 13.Available from: