Prader-Willi/Angelman Syndrome Molecular Detection
| Sunquest Code: | PWASMD | CoPath Code: | PWAS |
| Epic Code: | LAB4542 | Epic Name: | Angelman/Prader-Willi Methylation Analysis |
| Sunquest Code (non-Epic sites): | MD | ||
| Synonyms: | Prader Willi and Angelman | ||
| Methodology: | Methylation Sensitive Polymerase Chain Reaction (MS-PCR) | ||
| 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: | |||
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 (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) |
Interpretive
| 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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