In the further study for JAK2 V617F mutation rates among patient groups classified by blood cell counts, we found that JAK2 V617F mutation rate increased progressively with increase of RBC counts, and 96.61% patients were JAK2 V617F mutated in patients with RBC counts exceeding 6.5 (6.0)×1012/L, confirming the conclusion that JAK2 V617F occurred in almost all the PV patients [13]. Here, JAK2 is linked to acquired polycythemia vera.