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Calreticulin Gene Mutation

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

Test Codes

EPIC: LAB6878, Beaker: GCALG

Department

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 refrigerated (preferred) (2-8°C or 36-46°F) or at room temperature (20-26°C or 68-78.8°F) prior to transport.

Rejection Criteria

• Frozen specimens.
• Centrifuged specimens.
• Mislabeled or unlabeled tubes.
• Specimens collected in heparin tubes (Green-top), clot tubes (Red-top), or SST (Gold-top) tubes.
• Specimens not collected and processed as indicated.

Client will be notified of any cancellation of testing.

In-Lab Processing

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

Storage

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.

Laboratory

Royal Oak Molecular Pathology Laboratory

Performed

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 fragment analysis. Confirmatory testing by sequencing is performed as needed for unusual CALR variants.

Interpretation

The test detects insertion and deletion type mutations in exon 9 of CALR gene. Results are reported as positive or negative. The common type 1 (52-bp deletion) or type 2 (5-bp insertion) CALR mutations will be reported if applicable. Uncommon mutations other than types 1 and 2 will be reported with further interpretative comments after confirmatory testing is completed.

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

81219

Contacts

Last Updated

10/30/2023