Update Type: Test Methodology Changed
Test Updated: 03/31/2022
Test Overview
Test Methodology

Multi-locus imprinting MS-MLPA (Methylation Specific Multiplex Ligation-dependent Probe Amplification) is used to determine the methylation status and the copy number at imprinted loci in 15q11.2 (5’ SNRPN).

Test Usage

Testing for or confirmation of diagnosis or suspicion of Prader-Willi or Angelman syndrome.

Reference Range *

Interpretive report provided.

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Limitations

This assay is not able to identify the 11% of Angelman syndrome cases caused by defects in UBE3A or the other 10% of Angelman syndrome cases caused by unidentified genetic mechanism.

Test Details
Days Set Up
Monday - Friday
Analytic Time

14 - 21 days

Soft Order Code
MiChart Code
Prader-Willi/Angelman Syndrome Analysis
  • Generic Peds Genetics Test
  • Prader-Willi / Angelman Methylation Analysis
  • Prader-Willi / Angelman Methylation PCR
  • SNRPN Methylation Analysis
  • SNRPN Methylation PCR
  • Prader-Willi Syndrome
  • Angelman Syndrome
  • PWS/AS crit reg M-PCR Shadow
  • Autism / Intellectual Disability
MMGL Molecular Genetics
Specimen Requirements
Collection Instructions

Collect specimen in a lavender top tube. Send intact specimen within 24 hours if stored at room temperature or within 5 days if stored refrigerated. Include the patient's family history, pedigree, and ethnicity on the test requisition. Obtaining informed consent from the patient prior to genetic testing is strongly recommended. If desired, a UMHS Request and Consent for Genetic Testing form can be obtained from the MMGL Molecular Genetics Laboratory by contacting the MLabs Client Services Center at 800-862-7284 or online at https://mlabs.umich.edu/media/188.

Normal Volume
5 - 10 mL EDTA whole blood
Minimum Volume
2 mL EDTA whole blood
Additional Information

Aberrations affecting imprinted loci in 15q11-13 region, including deletions, uniparental disomy, or rare epimutations at imprinting center, account for more than 99% of Prader-Willi syndrome cases and approximately 80% of Angelman syndrome cases. These aberrations can be detected by MS-MLPA in the forms of abnormal methylation status and/or abnormal copy number at imprinted loci in 15q11.2 (5’ SNRPN gene). Depending on the specific abnormal results, additional tests including chromosomal microarray, uniparental disomy analysis and imprinting center sequencing may be needed to further determine the molecular mechanism. By ordering this test the clinician acknowledges that informed consent has been obtained from the patient as required by applicable state or federal laws and the ordering clinician has authorization from the patient permitting MLabs to report the test results to the ordering clinician. Test includes medical geneticist interpretation of results billed as a separate additional charge. This test is not available without interpretation.

CPT Code
Fee Code
Pro Fee CPT