Calreticulin Mutations in Philadelphia Chromosome Negative Myeloproliferative Neoplasms

Abstract

Calreticulin (CALR) is a multifunctional protein. CALR gene mutations are one of the driver mutations in cases with essential thrombocythemia (ET) and primary myelofibrosis (PMF). The aim of this study is to comprehend the functional relationship of CALR type1 and type2 mutations in the pathogenesis of Phi-ladelphia Chromosome Negative Myeloproliferative Neop-lasms (MPNs) by emphasizing the incidence, biological and clinical features of CALR mutations in Janus Kinase2 (JAK2) V617F mutation negative and thrombopoietin receptor gene (MPL) mutation negative ET and PMF cases, and to determine their effect on the disease phenotype. The laboratory results of cases analyzed with essential throm-bocythemia and primary myelofibrosis were analyzed retros-pectively. In our study of the ET cases, 18.4% CALR exon9 mutation car-ried, 5.1% a thrombopoietin receptor gene (MPL) mutation, and 57.1% JAK2 V617F mutation. 19.4% of our cases do not carry any of these three mutations. Our ET patients with CALR muta-tion positive, 61.1% have type1, 27.8% have type2 and 11.1% have mutations other than type1 and type2. In our study of the PMF cases, 27.7% CALR exon9 mutation carried, 3.6% a MPL mutation, and 47% JAK2 V617F muta-tion. 21.7% cases are triple negative. Our PMF patients with CALR mutation positive, 69.6% have type1, 30.4% have type2 mutations. CALR mutations are a new and important molecular marker for Philadelphia chromosome negative myeloproliferative neoplasm cases. Longer follow-up and larger case populations are required to investigate the effects of clinical and laboratory pa-rameters of diseases.