Among the increasing panel of additional mutations that might be implicated in the development or the progression of hematological malignancies, genetic alterations affecting epigenetic regulators, specifically DNA methylation and chromatin modification genes including TET2, DNMT3A, IDH1/2, ASXL1, and EZH2, were described as more frequent in PV than in other MPNs [114]. The gene discussed is IDH1; the disease is acquired polycythemia vera.