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HelpTest ID MPNR Myeloproliferative Neoplasm (MPN), JAK2 V617F with Reflex to CALR and MPL
Useful For
Aiding in the distinction between a reactive cytosis and a chronic myeloproliferative disorder
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| MPLR | MPL Exon 10 Mutation Detection, R | Yes, (order MPLB, MPLM or MPLVA) | No |
| CALX | CALR, Gene Mutation, Exon 9, Reflex | Yes, (order CALR) | No |
Testing Algorithm
This reflex test sequentially evaluates for the common major gene mutations associated with non-BCR/ABL1-positive myeloproliferative neoplasms until a mutation is identified. The testing sequence is based on the reported frequency of gene mutations in this disease group. Initial testing evaluates for the presence of the JAK2 V617F mutation. If this result is negative, testing proceeds with assessment for CALR mutations. If the CALR result is also negative, then testing proceeds to evaluate for mutations in exon 10 of the MPL gene. If either JAK2 V617F or CALR mutations are detected first in the process, the testing algorithm ends; therefore, the complete reflex is followed only in the event of sequential negative mutation. An integrated report is issued with the summary of test results.
The following algorithms are available in Special Instructions:
-Myeloproliferative Neoplasm: A Diagnostic Approach to Peripheral Blood
-Myeloproliferative Neoplasm: A Diagnostic Approach to Bone Marrow Evaluation
Special Instructions
Method Name
Point Mutation Detection in DNA Using Quantitative Polymerase Chain Reaction (PCR)
(PCR is utilized pursuant to a license agreement with Roche Molecular Systems, Inc.)
Reporting Name
MPN (JAK2 V617F, CALR, MPL) ReflexSpecimen Type
VariesThe following information is required:
1. Pertinent clinical history
2. Clinical or morphologic suspicion
3. Date of collection
4. Specimen source
Forms: If not ordering electronically, complete, print, and send a Hematopathology/Cytogenetics Test Request Form (T726) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/hematopathology-request-form.pdf)
Specimen must arrive within 168 hours (7 days) of collection.
Submit only 1 of the following specimens:
Specimen Type: Blood
Container/Tube: Lavender top (EDTA) or yellow top (ACD solution B)
Specimen Volume: 3 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send specimen in original tube.
3. Label specimen as blood.
Specimen Type: Bone marrow
Container/Tube: Lavender top (EDTA) or yellow top (ACD solution B)
Specimen Volume: 2 mL
Collection Instructions:
1. Invert several times to mix bone marrow.
2. Send specimen in original tube.
3. Label specimen as bone marrow.
Specimen Type: Extracted DNA from blood or bone marrow
Container/Tube: 1.5- to 2-mL tube with indication of volume and concentration of the DNA
Specimen Volume: Entire specimen
Collection Instructions: Label specimen as extracted DNA from blood or bone marrow.
Specimen Minimum Volume
Blood and Bone marrow: 0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Ambient (preferred) | 7 days |
| Refrigerated | 7 days |
Clinical Information
The Janus kinase 2 gene (JAK2) codes for a tyrosine kinase (JAK2) that is associated with the cytoplasmic portion of a variety of transmembrane cytokine and growth factor receptors important for signal transduction in hematopoietic cells. Signaling via JAK2 activation causes phosphorylation of downstream signal transducers and activators of transcription (STAT) proteins (eg, STAT5) ultimately leading to cell growth and differentiation. BCR-ABL1-negative myeloproliferative neoplasms (MPN) frequently harbor an acquired single nucleotide mutation in JAK2 characterized as c.G1849T; p. Val617Phe (V617F). The JAK2 V617F is present in 95% to 98% of polycythemia vera (PV), and 50% to 60% of primary myelofibrosis (PMF) and essential thrombocythemia (ET). It has also been described infrequently in other myeloid neoplasms, including chronic myelomonocytic leukemia and myelodysplastic syndrome. Detection of the JAK2 V617F is useful to help establish the diagnosis of MPN. However, a negative JAK2 V617F result does not indicate the absence of MPN. Other important molecular markers in BCR-ABL1-negative MPN include CALR exon 9 mutation (20%-30% of PMF and ET) and MPL exon 10 mutation (5%-10% of PMF and 3%-5% of ET). Mutations in JAK2, CALR, and MPL are essentially mutually exclusive. A CALR mutation is associated with decreased risk of thrombosis in both ET and PMF, and confers a favorable clinical outcome in PMF patients. A triple negative (JAK2 V617F, CALR, and MPL-negative) genotype is considered a high-risk molecular signature in PMF.
Reference Values
An interpretive report will be provided.
Cautions
A negative result does not exclude the presence of a myeloproliferative neoplasm or other neoplastic process.
In rare cases, a mutation other than the V617F may be present in an area that interferes with primer or probe binding and cause a false-negative result.
Day(s) Performed
Monday through Friday; 12 p.m.
Report Available
7 daysPerforming Laboratory
Mayo Medical Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.CPT Code Information
81270-JAK2 (Janus kinase 2) (eg, myeloproliferative disorder) gene analysis, p.Val617Phe (V617F) variant
81219-CALR (calreticulin) (eg, myeloproliferative disorders), gene analysis, common variants in exon 9
81403-MPL (myeloproliferative leukemia virus oncogene, thrombopoietin receptor, TPOR) (eg, myeloproliferative disorder), exon 10 sequence (if appropriate)