Aiding in the distinction between a reactive cytosis and a chronic myeloproliferative disorder
Evaluating mutations in CALR in an algorithmic process for the MPNR / Myeloproliferative Neoplasm, JAK2 V617F with Reflex to CALR and MPL, Varies
Only orderable as a reflex. For more information see MPNR / Myeloproliferative Neoplasm, JAK2 V617F with Reflex to CALR and MPL, Varies.
Polymerase Chain Reaction (PCR) and Fragment Analysis
Varies
Only orderable as a reflex. For more information see MPNR / Myeloproliferative Neoplasm, JAK2 V617F with Reflex to CALR and MPL, Varies.
Blood and Bone Marrow: 1 mL
Gross hemolysis | Reject |
Paraffin embedded bone marrow aspirate clot or biopsy blocks, slides, paraffin shavings Moderately to severely clotted | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Varies | Varies | 7 days |
Aiding in the distinction between a reactive cytosis and a chronic myeloproliferative disorder
Evaluating mutations in CALR in an algorithmic process for the MPNR / Myeloproliferative Neoplasm, JAK2 V617F with Reflex to CALR and MPL, Varies
The JAK2 (Janus kinase 2) gene codes for a tyrosine kinase (JAK2) 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, 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.
Only orderable as a reflex. For more information see MPNR / Myeloproliferative Neoplasm, JAK2 V617F with Reflex to CALR and MPL, Varies.
An interpretive report will be provided.
An interpretation will be provided under the MPNR / Myeloproliferative Neoplasm, JAK2 V617F with Reflex to CALR and MPL, Varies.
A positive result is not specific for a particular subtype of myeloproliferative neoplasm and clinicopathologic correlation is necessary in all cases.
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.
1. Klampfl T, Gisslinger H, Harutyunyan AS, et al. Somatic mutation of calreticulin in myeloproliferative neoplasms. N Engl J Med. 2013;369(25):2379-2390
2. Nangalia J, Massie CE, Baxter EJ, et al. Somatic CALR mutation in myeloproliferative neoplasms with nonmutated JAK2. N Engl J Med. 2013;369(25):2391-2405
3. Rumi E, Pietra D, Ferretti V, et al. JAK2 or CALR mutation status defines subtypes of essential thrombocythemia with substantially different clinical course and outcomes. Blood. 2014;123(10):1544-1551
4. Rotunno G, Mannarelli C, Guglielmelli P, et al. Impact of calreticulin mutations on clinical and hematological phenotype and outcome in essential thrombocythemia. Blood. 2014;123(10):1552-1555
5. Tefferi A, Lasho TL, Finke CM, et al. CALR vs JAK2 vs MPL-mutated or triple-negative myelofibrosis: clinical, cytogenetic and molecular comparisons. Leukemia. 2014;28(7):1472-1477
Polymerase chain reaction (PCR) amplification of CALR exon 9 is performed on DNA isolated from the patient sample. The PCR product is then run on an ABI Genetic Analyzer for fragment analysis to detect insertions and deletions. An unmutated CALR will show an amplicon at 266 base pairs (bp), a mutated CALR with insertion will show an amplicon greater than 266 bp, and a mutated CALR with deletion will show an amplicon smaller than 266 bp. This assay has an analytical sensitivity of approximately 6% (ie, 6 mutation-containing cells in 100 total cells) in most mutation types, except for the rare type of 1-bp deletion, which has a sensitivity of approximately 20%.(Unpublished Mayo method)
Monday through Friday
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
81219-CALR (calreticulin) (eg, myeloproliferative disorders), gene analysis, common variants in exon 9
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
CALX | CALR, Gene Mutation, Exon 9, Reflex | 77174-1 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
36998 | Final Diagnosis | 22637-3 |