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Prader-Willi syndrome (PWS) is a chromosome disorder that both boys and girls can be born with. It is when a certain part of the brain (the hypothalamus) does not work properly.


What is it like for siblings if their brother or sister has Prader-Willi syndrome (PWS)?

Lots of siblings get on very well with their brothers and sisters who have PWS. They have fun and enjoy spending time together. However, other siblings can find it difficult that there are strict rules about food and where it is kept in their homes. They might also find it unfair that their families have to keep to routines. This can make it hard to have friends round or to go for days out.

What causes PWS?

Each cell in your body contains small parts called chromosomes. There are 23 pairs of these in each cell. In PWS there is something different about the pair known as chromosome 15. This is something that happens before birth, but nobody knows why. This affects a part of the brain called the hypothalamus. This part of the brain controls how hungry someone is, how tall they grow, how they behave, and their emotions.

What does it mean?

The effect can differ quite a lot between different people. Babies are floppy and need help learning to feed and the big muscles will stay weak as they get older. They may have difficulty balancing and learning to walk and many people with PWS need help with their learning. The parts of the body which show if they are a boy or a girl may not grow properly. They often find it hard to control their emotions and can easily get angry or frustrated when they do not understand what is being said or what is happening. Their brain does not tell them when they have had enough to eat so they may eat too much and put on a lot of weight. They may look a bit different. When they grow up they may be shorter than usual. It’s very common for children with PWS to take growth hormone treatments and this helps many grow to average height. They may ask the same question or have the same conversation over and over again.

What treatment is there?

PWS cannot be cured but there are things that can help people with PWS. Routines and strict control of what people with PWS eat are very important to stop them becoming very overweight. Hormones are special chemicals that bodies make to help them do certain things. Injections of hormones can help someone with PWS to grow and develop. Special professionals will needed to help someone with PWS.

This information has been approved by The Prader-Willi syndrome Association, March 2024