Accordingly, the first step in approaching the diagnosis of PV should include JAK2 mutation screening, and we favor upfront targeting of both exons 14 and 12, in order to avoid undue delay in the diagnostic process; it should also be noted that peripheral blood and bone marrow samples are equally informative in detecting and quantifying JAK2V617F [52]. The gene discussed is JAK2; the disease is acquired polycythemia vera.