Phenotypic correlations of CALR mutation variant allele frequency in patients with myelofibrosis

All patients with confirmed WHO2016 and IWG-MRT diagnosis of PMF and PET-MF, respectively, available at the Center Research and Innovation of Myeloproliferative Neoplasms (CRIMM), Florence, were included in the study (MYNERVA project, IRB approval #14560). CALR mutation was assayed by PCR amplification and capillary gel electrophoresis starting from granulocyte DNA. CALR VAF was determined by automated interpolation of the area under the curve, and expressed as the ratio between the mutant peak area and the sum of mutant and wild-type peak areas x100. Mutation analysis of a panel of 40 myeloid neoplasm-associated genes, including CALR, was performed by NGS (Oncomine, ThermoFisher) [11]. The nonparametric Wilcoxon rank-sum test, Kaplan–Meier estimate of survival and log-rank test were used as appropriate. Reported P-values are two-sided; P < 0.05 was considered statistically significant.