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Lab Dept:
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Anatomic Pathology
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Test Name:
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PRADER-WILLI / ANGELMAN SYNDROME MOLECULAR ANALYSIS METHYLATION
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General Information
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Lab Order Codes:
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PWMA
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Synonyms:
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Prader Willi/Angelman Syndrome Methylation Study; Methylation PCR Prader-Willi/Angelman Syndrome
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CPT Codes:
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81331 – SNRPN/UBE3A, methylation analysis
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Test Includes:
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Methylation-Sensitive Multiple Ligation-Dependent Probe Amplification (MLPA) with an interpretive report of findings.
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Logistics
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Test Indications:
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Confirmation of diagnosis in patients suspected of having either Prader-Willi or Angelman Syndrome based on clinical assessment or previous laboratory analysis.
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Lab Testing Sections:
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Anatomic Pathology - Sendouts
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Referred to:
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Mayo Medical Laboratories (MML# 81153)
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Phone Numbers:
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MIN Lab: 612-813-6280
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STP Lab: 651-220-6550
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Test Availability:
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Daily, 24 hours
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Turnaround Time:
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14 – 21 days
Note: Specimens received Monday – Thursday will be processed for the run starting on the following Monday. Specimens received Friday – Sunday will be set up a week from the following Monday.
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Special Instructions:
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A “Molecular Genetics – Congenital Inherited Diseases Patient Information Sheet” (Mayo Supply T245) is required for all orders. An “Informed Consent Form for DNA Testing” (Mayo Supply T576) is available. Please contact the laboratory for forms.
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Specimen
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Specimen Type:
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Whole blood
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Container:
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Lavender top OR Yellow top ACD tube
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Draw Volume:
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3 mL (Minimum: 1 mL) blood
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Processed Volume:
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Same as Draw Volume
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Collection:
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Routine venipuncture
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Special Processing:
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Lab Staff: Do Not centrifuge. Submit specimen in original vacutainer tube at room temperature. Specimen must reach Mayo within 96 hours of collection. Forward promptly.
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Patient Preparation:
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None
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Sample Rejection:
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Mislabeled or unlabeled specimens
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Interpretive
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Reference Range:
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An interpretive report will be provided.
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Critical Values:
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N/A
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Limitations:
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The accuracy of the clinical assessment contributes to the likelihood of identifying a deletion or uniparental disomy. Rare cases of Prader-Willi Syndrome or Angelman Syndrome result from a subtle balanced translocation inherited from one of the parents. These may not be detected by this assay. A negative molecular test result, especially in the case of a clinical suspicion of Angelman Syndrome, does not rule out the diagnosis because point mutations may not be detected by these methods. Parental blood specimens may be requested if additional studies by polymerase chain reaction (PCR) are necessary to clarify the diagnosis.
In addition to disease-related probes, the MLPA technique utilizes probles localized to other chromosomal regions as internal controls. In certain circumstances, these control probes may detect other diseases or conditions for which this test was not specifically intended. Results of the control probes are not normally reported. However, in cases where clinically relevant information is identified, the ordering physician will be informed of the result and provided with recommendations for any appropriate follow-up testing.
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Methodology:
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Methylation-sensitive multiple ligation-dependent probe amplification (MLPA)
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References:
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Mayo Medical Laboratories Web Page June 2011
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Updates:
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1/13/2009: CPT updates
2/7/2013: CPT updates
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