PWS Info Letter

Dear Parents,

I am writing you because I was informed that you have a child with the Prader-Willi Syndrome (PWS). I have recently been researching this disorder and want to give you some information about it that you may not yet know and suggestions that may help in maintaining your child\'s health and safety.
Prader-Willi Syndrome is a two-stage non-hereditary genetic disorder that occurs in both male and females. The first stage is the mutation of gene expression, the second stage starts after the child is born. It is not very common, only 1 out of 15,000 people are born with it. It is caused by a genetic abnormality on the 15th chromosome.
On a normal person, you have 23 pairs of chromosomes. In each pair, 1 gene comes from the mother, and 1 gene comes from the father. This is how things get passed down from parents to children (like eye color, height, skin tone etc...).
However, in a person with PWS, the 15th chromosome has been given 2 genes from the mother, and none from the father. This is called maternal UPD ( uni-parent disomy) in which 2 copies of the maternal chromosome are inherited with no paternal contribution. Despite the presence of 2 intact chromosomes, there is a functional abnormality in the imprinting that may lead to the absence of gene expression from the paternally donated chromosome, resulting in the PWS phenotype (physical trait) that is common in persons with PWS.
The physical traits or symptoms of a person with PWS are due to the abnormality in the satiety center of the brain, (satiety is the sense of being "full" after eating, or knowing when your hungry and when your not). People with PWS do not have the sense of normal satiety, therefore they do not realize when they are "full" from eating. This leads to obesity, and uncontrolled eating habits. No medication has been found to treat this problem.
This means that people with PWS have to be maintained and controlled their entire life, basically they need 24-hour care. It is essential that food intake is controlled. Also, they will have to maintain good exercising habits, at least 30 minutes each day. This will not prevent them from being overweight, because of the body composition in PWS: muscles are small, muscle tone is low and the activity level is usually below normal. This also means, that people with PWS have a lower need for calories. A normal person needs the average 2000 calories a day, but someone with PWS only needs about 1000-1250 .
I believe that PWS is a very serious disorder that needs to be handled correctly and given a lot of care. If you need any more information or help with your PWS child, please feel free to contact Prader-Willi Syndrome Association (USA) toll free at 1-800-926-4797.