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