In our opinion, the increased total JAK2 expression in ET pts may result from different factors, including the allelic expression imbalance of JAK2 V617F mutation, MPN-associated chronic inflammation, the presence of other non-coding SNP affecting the JAK2 expression, or mutations of epigenetic genes regulators (DNMT3A, TET2, EZH2, ASXL1, and IDH1/2 (via effects on TET2-mediated methylation)). Here, IDH1 is linked to essential thrombocythemia.