Diagnosis of Prader-Willi syndrome

When to test for Prader-Willi syndrome

If the clinical signs and symptoms of Prader-Willi syndrome are present then it is recommended to conduct a DNA methylation test.

How to test for Prader-Willi syndrome

If the clinical features are present, and PWS is therefore suspected, it is recommended to conduct a DNA methylation test.

This will confirm the presence, or not, of the two main forms of PWS, but will not tell you which of the genetic types of PWS the child has. Further tests will be required for this.

How to access testing

Physicians are able to access testing in many countries.

If testing is not available in your country then you may be able to access free testing by using our service based in Italy, or if you are based in South America then another service is available. More information about both routes to free testing is available here.


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IPWSO was established so that PWS associations, families, clinicians and caregivers around the world could exchange information and support and have a united global voice under one umbrella.

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Find useful guides, research and information to help families manage PWS.

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