What is PWS?

Prader-Willi syndrome (often called PWS) is a complex medical condition that affects both males and females throughout their lives. People with PWS may need extra support with health and development and in the areas of education and work.

People with PWS may present some challenging learning and emotional behaviours and unusual medical issues. The syndrome typically causes low muscle tone with motor development delays, short stature if not treated with growth hormone, and incomplete sexual development. Most people with PWS are floppy at birth with initial difficulties in feeding, but then in early childhood begin to show increased appetite which can lead to excessive eating and life-threatening obesity.

Although PWS presents a group of features that occur together, it is important to remember that every child is an individual. Not every person with PWS will have all of these characteristics. Presentations will also vary in intensity from person to person. Increasingly, early diagnosis gives our children a more positive start with prompt intervention and sensible eating plans.

The name of the syndrome is derived from the names of two of the doctors who first described the pattern of characteristics associated with PWS in 1956.


“My child is just like his peers in so many ways – diverse, active and able to achieve!”


Why does PWS happen?

If your baby has just received a new diagnosis of PWS you might be feeling upset and confused. Or, if you have an older child, you might have just got the answer to years of not understanding why they seem a little different from their peers. You may be asking, why has my child got PWS?

It is important to know that a diagnosis of PWS is not your fault. Chromosomes come in pairs, and PWS is simply due to the baby failing to receive active paternal genes from a specific section of one chromosome 15. There are three main ways that this can happen.

• If your child has a ‘deletion’ (about 70% of all cases of PWS) it means that part of the chromosome 15 inherited from the child’s father is missing.

• If your child has ‘maternal uniparental disomy (UPD)’ (about 25% of cases) it means they have taken both copies of chromosome 15 from one parent — the mother.

• If you are told that your child has an ‘imprinting defect’ (less than 5% of cases) it means that the ‘PWS genes’ on the father’s chromosome 15 are present but do not work because the imprinting process is faulty. (Further testing and genetic counselling are especially important for families who have a child with an imprinting defect.)

Neither deletion nor UPD types of PWS are hereditary and neither type is likely to reoccur in the family.


Although there is currently no cure for PWS, continuing research does offer effective treatments and hope for a cure one day. Growth hormone treatment can improve muscle tone and stature. Sex hormone treatment can address hormone imbalance. A regulated lifestyle with dietary control supported by input from nutritionists and dietitians will have a positive impact on health and body weight. Physiotherapy, occupational therapy, speech and language therapy and the provision of special education (when appropriate) can help the child with PWS make good progress and meet their full potential.

However one of the most difficult symptoms associated with PWS remains untreated. To date, no effective medications have been found to regulate appetite. Inability to control food intake is often the biggest obstacle keeping those with PWS from living independently. Nevertheless, there are many effective ways of supporting the person to maintain a healthy weight.

“After she was born my child was very floppy. She needed help sucking and feeding. When she was two years old I noticed that her appetite was increasing. I knew I needed help because otherwise her obsession with food and eating was going to make her obese. PWSA UK worked with me to find ways to manage my daughter’s food behaviours and control her diet. I now plan family meals in a way which means our whole family has a much healthier approach to diet and my daughter responds well to our new mealtime routines.”



Having a child with special needs can be challenging and families may need extra support if their child has PWS. Many adults with PWS will benefit from access to a supervised occupation in a caring and understanding environment. Adults may need life-long continuous support and care in order to achieve a semi-independent lifestyle.


Find out more about PWS by following the links below:



We have a range of publications for both parents and professionals. 



Characteristics of PWS

Prader-Willi Syndrome (PWS) was first described in 1956 by Swiss doctors, Prof. A Prader, Dr A Labhart and Dr H Willi, who recognised the condition as having unique and clearly definable features. 



PWS is a rare disorder, and not everyone with an over-eating problem will have PWS.


Genetics of PWS

PWS is a complex genetic syndrome and research is uncovering many variations within it. This information reflects current knowledge, and therefore may change over time, as more research is carried out.


Endocrine disorders in PWS

It is fairly certain that dysfunction of the hypothalamus in the brain is the main cause of endocrine disorders in PWS. The most common are:


Growth hormone for children with PWS - UK Practice

Growth Hormone (GH) therapy is recommended for growth failure in children with Prader-Willi Syndrome (PWS) – this is supported by the National Institute of Health & Clinical Excellence (NICE) and this guidance is published as ‘Technology Appraisal 188’ by NICE.  The published guidance can be found at http://www.nice.org.uk/guidance/TA188/Guidance/pdf.  The guidance also suggests that response to GH therapy in PWS children should also consider body composition.


Health care in PWS

People with PWS are generally as healthy as the general population, and may also be prone to the same illnesses and diseases. However there are some unusual features of PWS which require special attention and may not always be evident to those who have little experience of the syndrome. The following is a list of those features. Please note that they vary in degree between individuals with PWS and not all people with PWS will necessarily have all the features.


Vision and care of the eyes in PWS

The chromosome abnormality that causes Prader-Willi syndrome leads to various problems in development, including a number of ocular features.



Weight management in PWS

Weight management is crucial to the long-term health and well-being of people with PWS. Babies with PWS often take food quite poorly. Once this stage is over, if the person does not keep to a lower calorie (energy) diet, they can quickly become very obese and therefore liable to all the conditions which generally accompany obesity, ie:


Behaviour management in PWS

Almost everyone with Prader-Willi syndrome presents with behaviour which can bring challenges to either themselves, or those around them, or both. However, this varies considerably between individuals. Behavioural challenges range from very mild to very severe, and each individual may display differing behaviours. These in turn may vary with age, external environment and emotional development. The degree of learning disability does not necessarily affect the severity of behavioural challenges. Those who have only mild learning disabilities are just as likely to have challenging behaviour as those with a severe learning disability.


Educating the child with PWS

This article is intended to give a general overview of the special educational needs of children with Prader-Willi syndrome, and to offer some hints on general classroom management. It should be borne in mind that each child with PWS is an individual, and one child will have varying abilities from another. It is essential that each child should be assessed as an individual in order to reach their full potential, but some account should also be taken of the effects which Prader-Willi syndrome will bring into that child's life.


Speech and language in PWS

Children with PWS may have the same range of disorders of speech and language development that can occur in any child. There is also the possibility of additional problems associated with the syndrome.


Ethical and legal issues

The most pressing ethical issue with regard to PWS is the dilemma of whether or not it is right to prevent access to food - in almost every other situation this would be regarded as against human rights. This article by our President, Professor Tony Holland, examines this issue and the potential use of the Mental Capacity Act 2005 in resolving it.