The mutational landscape of MPNs is rather homogeneous, as these neoplasms share a high incidence of the acquired point mutation (V617F) in the gene encoding Janus kinase 2 (JAK2), which is observed in approximately 98% of patients with PV and 50–60% of patients with PMF and ET [7]. The gene discussed is JAK2; the disease is acquired polycythemia vera.