Test Overview

Test Methodology

Polymerase chain reaction (PCR) with fragment analysis by capillary electrophoresis. Mutation confirmation by Sanger sequencing is performed on select cases.

Test Usage

CALR gene mutations occur at a frequency of 20-30% in primary myelofibrosis (PMF) and essential thrombocythemia (ET). Testing for CALR mutations can aid in the diagnosis of these myeloproliferative neoplasms. CALR mutations are typically exclusive of the JAK2 V617F mutation and are common (~50-75%) in PMF and ET cases that test negative for JAK2 V617F. The utilization of JAK2 V617F, CALR, and also MPL mutation testing provides detection of a clonal marker in the majority (>85%) of patients with PMF and ET. This CALR mutation test qualitatively detects all CALR exon 9 insertion and deletion mutations to a sensitivity of 2-5% mutant allele.

Reference Range*

Interpretive report provided.

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Limitations

The limit of detection of this assay is 10% mutation-bearing cells. Mutations may not be detected in samples with a neoplastic burden below this level.

Test Details

Analytic Time

2 - 7 days

Soft Order Code


MiChart Code

CALR Mutation



Primary Myelofibrosis (PMF)
Essential Thrombocythemia (ET)

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Molecular Diagnostics

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Specimen Requirements

Offsite Collection Instructions

Collect blood or bone marrow in a lavender top tube. Refrigerate and send intact blood or bone marrow specimen within 48 hours of collection. Fresh cell suspensions in RPMI should be refrigerated and sent, preferably within 48 hours. Frozen cell suspensions – preferably frozen with 1 hour of collection – may also be sent frozen on dry ice.


Lavender Top Tube

Normal Volume

5 mL EDTA (lavender) whole blood; 3 mL EDTA (lavender) bone marrow; Fresh/frozen cells in RPMI. Extracted DNA is also acceptable if extracted in a CLIA certified laboratory.

Additional Information

By ordering this test the clinician acknowledges that informed consent has been obtained from the patient as required by applicable state or federal laws and the ordering clinician has authorization from the patient permitting MLabs to report the test results to the ordering clinician. Test includes pathologist interpretation of results billed as a separate additional charge. This test is not available without interpretation.

Billing Information

Fee Codes

CPT Code


New York State Approved


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