Hypermethylation of CpG islands in SOCS1 and SOCS3 associated with a decrease in expression was found in JAK2V617F polycythemia vera and ET as well as in JAK2V617F and MPLW515-mutation negative ET.29 However, other authors could not confirm the hypermethylation of these genes although they observed differences in the gene expression pattern among MPN in a significant proportion of patients with idiopathic myelofibrosis but not in patients with polycythemia vera or ET.30, 31 Recently, Jost et al.32 reported methylation of SOCS1 in 15% of MPD patients. This evidence concerns the gene SOCS3 and essential thrombocythemia.