Specifically, in MPN patients with mutations in both JAK2 and TET2, the acquisition of TET2 mutation prior to JAK2 mutation was found to diminish the proliferative effect of JAK2 p.V617F, resulting in an earlier manifestation of MPN and tendency towards an ET phenotype, compared to patients where the JAK2 mutation occurred first with a tendency towards a PV phenotype. This evidence concerns the gene JAK2 and acquired polycythemia vera.