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Calreticulin (CALR) Mutation Analysis
Message*Collect specimen Monday through Friday only before 1500 EST. Do not collect the day before a holiday.
Test Code
LAB00500
Alias/See Also
LAB00500
LabCorp TC: 489450
LabCorp TC: 489450
CPT Codes
81219
Preferred Specimen
5.0 mL Lavender (EDTA) - Whole blood
Minimum Volume
3.0 mL Lavender (EDTA) - Whole Blood
Other Acceptable Specimens
Dark Green Top (Sodium Heparin)
1.0 mL Bone Marrow
1.0 mL Bone Marrow
Transport Temperature
Refrigerated
Specimen Stability
Refrigerated: 72 hours
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Specimen does not meet collection criteria; frozen whole blood, marrow, or cell pellet; leaking tube; clotted blood or marrow; grossly hemolyzed specimen or otherwise visibly degraded; contaminated by another specimen; specimens containing suspicious foreign material.
Methodology
Polymerase Chain Reaction (PCR); capillary electrophoresis
Report Available
5-7 days
Limitations
This PCR assay is capible of detecting a mutant cell popluation with a sensitivity of 5 mutant cells per 100 normal cells. A negative result does not exclude the presnce of a myeloproliferative disorder or other neoplastic process.
Clinical Significance
The calcium-binding endoplasmic reticulin chaperone protein, calreticulin (CALR), is somatically mutated in approximately 70% of patients with JAK2-negative essential thrombocythemia (ET) and 60% to 88% of patients with JAK2-negative primary myelofibrosis. Only a minority of patients (approximately 8%) with myelodysplasia has mutations in the CALR gene. CALR mutations are rarely detected in patients with de novo acute myeloid leukemia, chronic myelogenous leukemia, lymphoid leukemia, or solid tumors. CALR mutations are not detected in polycythemia and appear to be mutually exclusive with JAK2 mutations and MPL mutations.
The majority of mutational changes involve a variety of insertion or deletion mutations in exon 9 of the calreticulin gene: approximately 53% of all CALR mutations are a 52 bp deletion, while the second most prevalent mutation (approximately 32%) contains a 5 bp insertion. The remaining mutations consist of mostly deletions ranging from 1 bp to 52 bp and 1 or 2 insertion mutations.
The detection of a CALR gene mutation aids in the specific diagnosis of a myeloproliferative neoplasm, and help distinguish this clonal disease from a benign reactive more indolent disease course with a lower thrombotic risk and longer overall survival (relative to those with a JAK2 mutation).
Performing Laboratory
LabCorp