Calreticulin Exon 9 Mutation

Our qualitative test for CALR exon 9 insertion/deletion mutations is performed by PCR using purified genomic DNA with intron-located primers that flank and amplify exon 9 of CALR.

The somatic insertion/deletion mutations in exon 9 of the CALR gene have been associated with several chronic myeloproliferative disorders, including essential thrombocythemia (ET) and primary myelofibrosis (PMF) and infrequently other myeloid stem cell disorders. In the studies published to date, CALR mutations have been found in approximately 20-25% of ET patients, and 30-35% of PMF patients. Less commonly, this mutation may be found in some low grade myelodysplastic syndromes and other myeloid stem cell disorders.

The most common subtypes of CALR mutations reported include the type 1 mutation (52 base pair deletion) and the type 2 mutation (5 base pair insertion). For these mutation subtypes, additional Sanger sequencing will not be performed. For other mutation subtypes, specifically non-Type 1 and non-Type 2, sequencing will be performed to confirm the size of the deletion/insertion.

This testing can also be performed as part of JAK2 reflexive testing.

Limit of Detection: 2%

Limit of Detection Sanger sequencing: 20%

Hematopathology test request form found at Request Form

Preferred:
Blood: 6mL in Lavender Top (EDTA)

Bone Marrow: 1-2mL in Lavender Top (EDTA)

Tissue, Fluids or Sorted cells: Sterile container in RPMI

Slides: 10 unstained

Accepted:
Green Tops (Heparin), while green tops are accepted for testing, there is documentation that heparin can interfere with some PCR assays.

Extracted DNA will only be accepted from CLIA certified laboratories.

Tissue from stained or cover-slipped slides

Unacceptable:
Specimens received beyond stability limit.
Specimens with low volume or inadequate WBC
Formalin-fixed paraffin embedded tissue (FFPE/PET)
Decalcified or unacceptable fixatives

Send specimens to Hematopathology – Molecular department for processing.

The stability limit for Blood and Bone Marrow is 7 days, samples beyond this limit will be rejected.