Clinical meaning of JAK2 V617F mutation in chronic myeloproliferative disorders – the first experience
Abstract
Background An acquired V617F mutation in the JAK2 gene was found to occur in most patients with polycythaemia vera (PV), and about a half of those with essential thrombocythaemia (ET) and chronic idiopathic myelofibrosis (CIMF). It is the first clonal marker that allows differentiation between reactive thrombocytosis and erythrocytosis from some chronic myeloproliferative disorders (CMPD) – ET, PV and CIMF. It has been proposed that the JAK2 status could also divide ET patients in two distinct subgroups, with mutation positive one showing clinical and laboratory features of PV.
Patients and Allele-specific PCR for JAK2 mutation was done in 53 patients (35 ET, 12 PV and 6 CIMF). methods In the group of ET patients, some clinical and laboratory features of mutation positive and mutation negative subgroup were compared.
Results In general we found V617F mutation in 12/12 (100 %) PV, in 15/35 (43 %) ET and in 2/6 (33 %) CIMF. Mutation positive ET patients had higher haemoglobin (Hb) level and lower platelet counts already at diagnosis. The Hb level had the tendency to increase (observation period 35 months) and 2 patients converted to overt PV. In mutation negative patients the Hb level remained equal or even was slightly decreased after observation period (42 months). Up to now there is no statistical difference in leukocyte count, incidence of splenomegaly, antiproliferative drugs demand or disease related complications. Platelet distribution width (PDW) was higher in mutation positive group.
Conclusions The fraction of V617F mutation positive patients with CMPD in our work is similar to that found by others. We found this test very useful in differentation of some CMPD cases from the reactive states. Mutation positive ET shares some clinical and laboratory features with PV and overt polycythemic transformation in such patients is possible.
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References
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