Lab Test

Calreticulin Gene Mutation

CALR Gene Mutation, Primary Myelofibrosis, PMF, Essential Thrombocytosis, ET, exon 9, thrombocythemia, Myeloproliferative Neoplasm

Test Codes

EPIC: LAB6878, Code: GCALG


Molecular Pathology

Specimen Collection Criteria

Collect: Blood OR Bone Marrow.

  • Blood: 10 mL whole blood in Lavender-top EDTA tubes or Yellow-top ACD tubes. (Minimum: 5.0 mL)
  • Bone Marrow: 1.0 mL bone marrow aspirate in a Lavender-top EDTA tube. (Minimum: 0.5 mL)

Physician Office/Draw Specimen Preparation

Do not freeze specimens. Maintain specimen at room temperature (20-26°C or 68-78.8°F) prior to transport.

Preparation for Courier Transport

Transport: Whole blood or bone marrow at room temperature (20-26°C or 68-78.8°F).

Rejection Criteria

  • Frozen specimens.
  • Unlabeled tubes.
  • Specimens collected in heparin (Green-top), clot tubes (Red-top), or SST (Gold-top) tubes.

In-Lab Processing

Do not freeze specimens. Maintain specimen refrigerated (2-8°C or 36-46°F) prior to testing.


Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 72 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Extracted DNA may be available for additional testing if clinically indicated. Contact the Molecular Pathology Laboratory for verification.


Royal Oak Clinical Molecular Pathology Laboratory


Once per week.
Results available in 7-10 days.

Reference Range

Negative (no mutation).

Test Methodology

Genomic DNA isolated from peripheral blood or bone marrow aspirate is PCR amplified with a primer pair specific for flanking regions of exon 9 of the CALR gene; mutation analysis of the amplified PCR product is performed by high resolution capillary electrophoresis.


The test detects insertion and deletion type mutations in exon 9 of CALR gene. Results are reported as positive or negative (Type 1 (52-bp deletion) or Type 2 (5-bp insertion) CALR mutations will be reported if applicable).

Clinical Utility

Somatic mutations in the CALR gene has been reported in myeloproliferative neoplasms negative for JAK2 and MPL mutations. All reported mutations are insertions or deletions in exon 9. Mutations are found in 50-70% of essential thrombocythemia (ET) cases and in 70-80% of primary myelofibrosis (PMF) cases negative for JAK2 and MPL mutations; CALR mutation positivity provides an important molecular marker for diagnosis of ET and PMF. In addition to diagnostic utility, CALR mutations have been reported to be associated with favorable disease outcome.

CPT Codes



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