JAK2 and acquired polycythemia vera: Patients with the mutated JAK2 exon 12 were also having significantly higher haemoglobin levels (p < 0.001) and lower platelet (p < 0.001) and leukocyte counts (p < 0.001), but a similar thrombotic risk (p = 0.40) to those with JAK2 V617F-mutated PV [95].