Prader-Willi/Angelman Syndrome Molecular Detection

Abbrev Code:PWASMD   
Order Code:LAB4542Order Name:Angelman/Prader-Willi Methylation Analysis
Synonyms:Prader Willi and Angelman
Methodology:Methylation Sensitive Polymerase Chain Reaction (MS-PCR)
CPT Codes: 81331 x1, G0425 x1
Turnaround Time:Performed Mon-Fri. Results are reported within 14 days.
Special Instructions:A signed informed consent in the patient's medical record is required; the consent should not be sent to the laboratory. The link to the Genetic Testing Consent Form is provided as a convenience for the providers and genetic counselors. Bone Marrow Transplant Patients; If a patient is the recipient of an allogeneic transplant, this test must be done on a pre-transplant sample. Contact the Molecular Diagnostics lab to see if a pre-transplant sample is available.
Associated Links:

Genetic Testing Consent Form

Collection Instructions

Specimen:Blood or bone marrow
Optimal Volume:10 mL
Minimum\Peds Volume:5 mL
Container:Yellow (ACD, Solution A) tube available from laboratory
Alternate Containers: Purple (EDTA)
Causes for Rejection:Clotted specimen, incorrect anticoagulant, or frozen specimen, specimen more than 5 days old. Patients are only tested ONCE; if duplicate sample is collected, testing is canceled, credited and original results and collection date reported. Contact 612-273-8445 with questions.
Shared blood or bone marrow samples will not be accepted unless sent to Molecular first. Contamination will occur on automated hematology analyzers.  DNA extracted at non-CLIA certified (or equivalent) lab.

Processing and Shipping

Specimen Processing:Do not process. Store at room temperature.
Shipping Instructions:Ship at room temperature.
Test Performed at or Referral Lab Molecular Diagnostics  (UMMC East Bank)


Reference Range:By report.
Use:Analysis of allelic methylation differences at SNRPN locus can differentiate the maternally and paternally inherited chromosome 15 and can be used as a diagnostic test for PWS and AS. Methylation analysis of the SNRPN gene has been recognized by the ASHG/ACMG Test and Technology Transfer Committee as a clinically and scientifically valid diagnostic test for PWS/AS. MS-PCR is performed with DNA treated with sodium bisulfite, which converts cytosine but not methylated cytosine, to uracil. Based on the differential effect, the bisulfite-modified DNA of an unmethylated allele can be distinguished from that of a methylated allele by amplification with primers specific for a methylated and unmethylated allele (1,3,6).

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