In a recent report, approximately 98% of polycythemia vera patients have JAK2-V617F or JAK2 exon12 mutation. There is a genetic mutation (JAK2-V617F, MPL, or CALR mutation) in approximately 80% of essential thrombocythemia patients. Genetic mutation analysis is necessary for the diagnosis of myeloproliferative neoplasms, but, at present, such analysis can be carried out in only a few facilities. This study is a retrospective analysis of the results of peripheral blood examination of PV and ET patients and secondary polycythemia and reactive thrombocytosis. The purpose of this analysis is to predict the JAK2-V617F mutation by establishing a screening examination method. Results showed that the IPF count was significantly higher in PV and ET patients. In addition, the NAP score was significantly higher in JAK2-positive PV and ET patients. Furthermore, the results of ROC analysis, AUC of IPF count, and NAP score were more than 0.9, and these had a high capability to predict the JAK2-V617F variation. For the IPF count, the cut-off level is 10,000/μL (100% true positive rate, 16.7% false positive rate), whereas for the NAP score, the cut-off level is 250 (85.7% true positive rate, 25.0% false positive rate). We divided these patients into 4 groups, namely, A (IPF count <10,000/μL & NAP score <250), B (IPF count <10,000/μL & NAP score ≥250), C (IPF count ≥10,000/μL & NAP score <250), and D (IPF count ≥10,000/μL & NAP score ≥250). 91.7% of secondary polycythemia and reactive thrombocytosis patients were classified in group A or B; on the other hand, the true positive rate of JAK2 mutations in group D was 94.7%. These study results indicate that the IPF count and NAP score in PV and ET are useful for the differentiation of treatment-responsive patients, and there is a possibility that they can be used to quickly and easily predict the JAK2-V617F mutation.
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