The assessment of CALR exon 9 mutations in Essential Thrombocythemia (ET) patients

Introduction: Calreticulin is a protein that in humans is encoded by the CALR Gene. Calreticulin acts as a Ca2+-binding chaperone which bind misfolded proteins and prevents them from being exported from the Endoplasmic reticulum to the Golgi apparatus. Recently, somatic mutations of CALR gene have been reported in Myeloproliferative Neoplasms(MPNs). All reported mutations in CLRA are frame shift, insertion, deletion in exon 9 . Methods: In this study, we analyzed CALR exon 9 somatic mutation in 54 Essential Thrombocythemia (ET) patients by using a fluorescently labeled primer and DNA fragment analysis. ARMS-PCR was used for the detection of JAK2(V617F) gene mutations. We analyzed also findings at presentation . Result: Among 54 patients (30 to 83 years) with Essential Thrombocythemia, 30 (55.6%) had JAK2 mutations and 5 (9.3%) had CALR mutations, for a total mutation frequency of 64.8% . patients with mutations in CALR had a lower WBC compared with patients who have mutations in JAK2(P=0.01). In addition, the age of patients with CALR mutations was younger than those with JAK2 mutations (53.5 years vs 63 years). There was no significant difference among the JAK2+ and CALR+ patients in terms of platelet counts and hemoglobin levels. Discussion: Information on the proportion of patients carrying mutations in the JAK2 , CALR and c-MPL genes is important for genetic screening of patients with suspected BCR-ABL1- negative myeloproliferative or myelodysplastic/myeloproliferative neoplasm.

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CALR mutation.JAK2 mutation