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Prader-Willi Syndrome/Angelman Syndrome Methylation Analysis
Clinical Genetic Test
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offered by
Institute for Genomic Medicine (IGM) Clinical Laboratory
View lab's test page
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GTR Test Accession: Help GTR000196491.9
CAP
INHERITED DISEASENERVOUS SYSTEMSYNDROMIC DISEASE ... View more
Last updated in GTR: 2021-08-23
View version history
Last annual review date for the lab: 2025-05-16 LinkOut
At a Glance
Test purpose: Help
Diagnosis
Conditions (2): Help
Prader-Willi syndrome; Angelman syndrome
Genes (1): Help
SNRPN (15q11.2)
Methods (1): Help
Molecular Genetics - Methylation analysis: Methylation-specific PCR
Target population: Help
Patients suspected of having Angelman syndrome or Prader-Willi syndrome
Clinical validity: Help
Clinical sensitivity of this test is greater than 99% for …
Clinical utility: Help
Establish or confirm diagnosis
Ordering Information
Offered by: Help
Institute for Genomic Medicine (IGM) Clinical Laboratory
View lab's website
View lab's test page
Specimen Source: Help
Who can order: Help
  • Genetic Counselor
  • Health Care Provider
  • Licensed Physician
  • Nurse Practitioner
Test Order Code: Help
PWSASMETHYL
View other test codes
CPT codes: Help
**AMA CPT codes notice

Copyright: 2023 American Medical Association. All rights reserved.

Contact Policy: Help
Laboratory can only accept contact from health care providers. Patients/families are encouraged to discuss genetic testing options with their health care provider.
How to Order: Help
Submit a sample with a completed requisition form. Label sample and form with at least two patient identifying information, such as name and date of birth.
Order URL
Test development: Help
Test developed by laboratory (no manufacturer test name)
Informed consent required: Help
No
Test strategy: Help
This methylation analysis via methylation-specific PCR (M-PCR) [Test Code: PWSASMETHYL] should be ordered first to efficiently identify individuals with Prader-Willi syndrome or Angelman syndrome due to 15q11.2-q13 deletions, UPD15, or imprinting abnormalities.
Patients with ABNORMAL methylation pattern consistent with Angelman syndrome can reflex to chromosomal microarray analysis to evaluate … View more
View citations (4)
  • Dagli AI, Mathews J, Williams CA. Angelman Syndrome. 1998 Sep 15 [updated 2025 May 01]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025. PMID: 20301323.
  • Driscoll DJ, Miller JL, Cassidy SB. Prader-Willi Syndrome. 1998 Oct 06 [updated 2024 Dec 05]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025. PMID: 20301505.
  • https://www.ncbi.nlm.nih.gov/books/NBK1144
  • https://www.ncbi.nlm.nih.gov/books/NBK1330
Pre-test genetic counseling required: Help
No
Post-test genetic counseling required: Help
No
Recommended fields not provided:
Lab contact for this test
Conditions Help
Total conditions: 2
Condition/Phenotype Identifier
Test Targets
Genes Help
Total genes: 1
Gene Associated Condition Germline or Somatic Allele (Lab-provided) Variant in NCBI
Methodology
Total methods: 1
Method Category Help
Test method Help
Instrument *
Methylation analysis
Methylation-specific PCR
* Instrument: Not provided
Clinical Information
Test purpose: Help
Diagnosis
Clinical validity: Help
Clinical sensitivity of this test is greater than 99% for Prader-Willi syndrome and ~80% for Angelman syndrome.
View citations (4)
  • Dagli AI, Mathews J, Williams CA. Angelman Syndrome. 1998 Sep 15 [updated 2025 May 01]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025. PMID: 20301323.
  • Driscoll DJ, Miller JL, Cassidy SB. Prader-Willi Syndrome. 1998 Oct 06 [updated 2024 Dec 05]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025. PMID: 20301505.
  • https://www.ncbi.nlm.nih.gov/books/NBK1144
  • https://www.ncbi.nlm.nih.gov/books/NBK1330
Clinical utility: Help
Establish or confirm diagnosis
View citations (2)
  • Dagli AI, Mathews J, Williams CA. Angelman Syndrome. 1998 Sep 15 [updated 2025 May 01]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025. PMID: 20301323.
  • https://www.ncbi.nlm.nih.gov/books/NBK1144

Target population: Help
Patients suspected of having Angelman syndrome or Prader-Willi syndrome
View citations (2)
  • Dagli AI, Mathews J, Williams CA. Angelman Syndrome. 1998 Sep 15 [updated 2025 May 01]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025. PMID: 20301323.
  • Driscoll DJ, Miller JL, Cassidy SB. Prader-Willi Syndrome. 1998 Oct 06 [updated 2024 Dec 05]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025. PMID: 20301505.
Variant Interpretation:
Are family members with defined clinical status recruited to assess significance of VUS without charge? Help
No.

Will the lab re-contact the ordering physician if variant interpretation changes? Help
No.
Recommended fields not provided:
What is the protocol for interpreting a variation as a VUS?, Is research allowed on the sample after clinical testing is complete?, Sample negative report, Sample positive report
Technical Information
Test Procedure: Help
Positive results are confirmed using a second PCR reaction using alternate primers
Test Confirmation: Help
Positive results are confirmed using a second PCR reaction using alternate primers
Availability: Help
Tests performed
Entire test performed in-house
Analytical Validity: Help
Analytical Sensitivity >99%. Analytical Specificity >99%. Accuracy/Precision >99%.
View citations (1)
  • Ramsden SC, Clayton-Smith J, Birch R, Buiting K. Practice guidelines for the molecular analysis of Prader-Willi and Angelman syndromes. BMC Med Genet. 2010;11:70. doi:10.1186/1471-2350-11-70. Epub 2010 May 11. PMID: 20459762.
Assay limitations: Help
This methylation analysis via methylation-specific PCR (M-PCR) can identify individuals with Prader-Willi syndrome (PWS) or Angelman syndrome (AS) due to 15q11.2-q13 deletions, UPD15, or imprinting abnormalities. Abnormal methylation result is seen in more than 99% of patients with PWS and about 80% of patients with AS. About 10% of patients … View more
View citations (4)
  • Dagli AI, Mathews J, Williams CA. Angelman Syndrome. 1998 Sep 15 [updated 2025 May 01]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025. PMID: 20301323.
  • Driscoll DJ, Miller JL, Cassidy SB. Prader-Willi Syndrome. 1998 Oct 06 [updated 2024 Dec 05]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025. PMID: 20301505.
  • https://www.ncbi.nlm.nih.gov/books/NBK1144
  • https://www.ncbi.nlm.nih.gov/books/NBK1330
Proficiency testing (PT):
Is proficiency testing performed for this test? Help
Yes

Method used for proficiency testing: Help
Formal PT program

PT Provider: Help
College of American Pathologists, CAP
Recommended fields not provided:
Description of internal test validation method, Description of PT method, Major CAP category, CAP category, CAP test list
Regulatory Approval
FDA Review: Help
Category: Not Applicable
Additional Information

IMPORTANT NOTE: NIH does not independently verify information submitted to GTR; it relies on submitters to provide information that is accurate and not misleading. NIH makes no endorsements of tests or laboratories listed in 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.