The SNP rs2201862, located downstream of MECOM gene, had the third strongest influence on the risk of developing MPN, after the JAK2 46/1 haplotype and TERT rs2736100 polymorphisms, MECOM rs2201862 was found to predispose especially to PV and to CALR mutated ET and PMF (Figure 1) [23]. This evidence concerns the gene JAK2 and acquired polycythemia vera.