CALRETICULIN (CALR) MUTATION

Test Code
CALR (LABCORP 489450)

CPT Codes
81219

Preferred Specimen
Lavender-top (EDTA) tube or green-top (sodium heparin) tube

Minimum Volume
3 mL WHOLE BLOOD

Specimen Stability
AMBIENT : 72 HR
REF: 72 HRS

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



The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.