U.S. flag

An official website of the United States government

GTR Home > Tests > Prader Willi-Angelman Syndrome Methylation-Specific PCR Analysis


Test order codeHelp: PWAS PCR

Test name


Prader Willi-Angelman Syndrome Methylation-Specific PCR Analysis (PWAS-PCR)

Purpose of the test


This is a clinical test intended for Help: Diagnosis



Loading data ......

Click Indication tab for more information.

How to order


Peripheral blood (3 mL) in EDTA (lavender top) tube. Transport at room temperature. Please label with patient name, date of birth, date and time of collection of sample. Alteratively, a buccal swab can be submitted for testing with same labeling requirements. Please submit sample with a completed Molecular Diagnostics requisition found at www.DukeMolecular.org
Order URL Help: http://www.DukeMolecular.org/

Specimen source

Buccal swab
Peripheral (whole) blood
Specimen requirements: http://www.DukeMolecular.org/


Molecular Genetics
MMethylation analysis
Methylation-specific PCR
  • Applied Biosystems 3130XL
  • None/not applicable

Summary of what is tested

Loading data ......

Click Methodology tab for more information.

Clinical utility


Not provided

Clinical validity


This test will identify large disease-causing deletions, uniparental disomy or methylation patterning defects in the Prader-Willi / Angelman critical region. Other cause of PWS or AS, including small deletions within the disease critical region, point mutations within the UBE3A gene or mechanisms other than those cited above, will not be detected by this assay. This assay detects 99% of PWS cases and about 80% of AS cases. Somatic mosaicism in a PWS or AS patient may cause a false negative result. This result does not rule out a diagnosis of PWS or AS due to small deletions or other mechanisms not detected by this assay. Poor genomic DNA quality or quantity, the presence of PCR inhibitors, and mutations or polymorphisms in the PCR primer binding sequences can result in un-interpretable or (rarely) inaccurate results.


Not provided

Test services

  • Clinical Testing/Confirmation of Mutations Identified Previously

IMPORTANT NOTE: NIH does not independently verify information submitted to the GTR; it relies on submitters to provide information that is accurate and not misleading. NIH makes no endorsements of tests or laboratories listed in the GTR. GTR is not a substitute for medical advice. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.