We also be aware that it is needed to have methodologies that can precisely quantify the burden of CALR mutant alleles allowing the physicians to indirectly monitor treatment responses to specific therapies like situations in which the quantitative levels of Jak2 V617F allele burden were used as the predictive marker for treatment response in PV patients [15, 24, 25]. This evidence concerns the gene CALR and acquired polycythemia vera.