Interpretation
CALR mutations are found in patients with JAK2 V617F mutation negative essential thrombocythemia (ET) and primary myelofibrosis (PMF). Somatic mutations in CALR are found as insertions and deletions in exon 9. These mutations in conjunction with clinical features of ET or PMF can be used as a tool in the diagnosis of these disorders.
CALR exon 9 mutations are found in approximately 65% of non-JAK2 mutated ET and 85% of non-JAK2 mutated PMF.
In both ET and PMF, CALR mutations are associated with a lower risk of thrombosis and longer overall survival than JAK2 mutations. Klamfl et al. (2013) NELM, 369(25):2379-2390.
Limit of Detection: 1% mutant copies over total CALR gene copies.
If mutations are not detected in the CALR gene consider MPL gene mutation testing.
Test Method
PCR and fragment analysis to detect insertion/deletion mutations in the coding region of exon 9 of the CALR gene.
Mutations are characterised by Sanger sequencing.
