JAK2V617F Mutation Analysis, Quantitative, With Reflex to CALR Mutation Analysis and MPL Mutation Analysis

CPT: 81270
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Test Details

Use

The Quantitative Real-Time PCR assay detects V617F mutation (c.1849 G>T) observed in approximately 95% polycythemia vera (pv), 55% essential thrombocythemia (ET) and 55% primary myelofibrosis (PMF). It is also infrequently present (3 to 5%) in myelodysplastic syndrome, chronic myelomonocytic leukemia, and other atypical chronic myeloid disorders. The results should be interpreted in the context of all clinical and laboratory findings. No therapeutic action should be taken based solely on these results.

Limitations

In vitro studies have indicated that this assay has an analytical sensitivity of 1% for the detection of cells containing the JAK2V617F mutation, 5% for CALR and 10% to 20% for MPL mutations in a background of non-mutant cells.

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).

Methodology

Polymerase chain reaction (PCR); capillary electrophoresis; Sanger sequencing

Additional Information

The calcium-binding endoplasmic reticulin chaperone protein, calreticulin (CALR), is somatically mutated in approximately 70% of patients with JAK2-negative essential thrombocythemia (ET) and 60% to 88% of patients with JAK2-negative primary myelofibrosis. Only a minority of patients (approximately 8%) with myelodysplasia has mutations in CALR gene. CALR mutations are rarely detected in patients with de novo acute myeloid leukemia, chronic myelogenous leukemia, lymphoid leukemia, or solid tumors. CALR mutations are not detected in polycythemia and appear to be mutually exclusive with JAK2 mutations and MPL mutations.

MPL (myeloproliferative leukemia virus oncogene homology) belongs to the hematopoietin superfamily and enables its ligand thrombopoietin, to facilitate both global hematopoiesis and megakaryocyte growth and differentiation. MPL W515 mutations are present in patients with primary myelofibrosis (PMF) and essential thrombocythemia (ET) at a frequency of approximately 5% and 1%, respectively. The S505 mutation is detected in patients with hereditary thrombocythemia.

Specimen Requirements

Specimen

Whole blood or bone marrow

Volume

3 to 5 mL whole blood or 1 to 2 mL bone marrow

Minimum Volume

3 mL whole blood or 1 mL bone marrow

Container

Lavender-top (EDTA) tube or green-top (sodium heparin) tube

Collection

Submit at room temperature. Specimen should arrive at the testing laboratory within 48 hours of collection. Indicate the date and time of collection on test request form.

Storage Instructions

Ship at room temperature. If specimen is to be stored prior to shipment, store at 2°C to 8°C.

Causes for Rejection

Sample more than 72 hours old; frozen whole blood, serum or bone marrow; leaking tube; clotted blood or bone marrow; grossly hemolyzed specimen or otherwise visibly degraded or unsuitable; and specimens containing suspicious foreign material

Clinical Information

Special Instructions

Please provide indications for JAK2 testing and specimen type. Direct any questions regarding this test to customer service at 800-345-4363.

References

Alghasham N, Alnouri Y, Abalkhail H, Khalil S. Detection of mutations in JAK2 exons 12-15 by Sanger sequencing. Int J Lab Hematol. 2016 Feb;38(1):34-41.26361084
Baxter EJ, Scott LM, Campbell PJ, et al. Acquired mutation of the tyrosine kinase JAK2 in human myeloproliferative disorders. Lancet. 2005 Mar 19-25;365(9464):1054-1061.15781101
Erratum: Lancet. 2005 Jul 9-15;366(9480):122.
James C, Ugo V, Le Couédic JP. A unique clonal JAK2 mutation leading to constitutive signaling causes polycythaemia vera. Nature. 2005 Apr 28;434(7037):1144-1148.15793561
Kralovics R, Passamonti F, Buser AS, et al. A gain-of-function mutation of JAK2 in myeloproliferative disorders. N Engl J Med. 2005 Apr 28;352(17):1779-1790.15858187
Ma W, Kantarjian H, Zhang X, et al. Mutation profile of JAK2 transcripts in patients with chronic myeloproliferative neoplasias. J Mol Diagn. 2009 Jan;11(1):49-53.19074595

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