Moreover, allelic ratios higher than 50% JAK2-V617F, indicating the presence of granulocytes homozygous for JAK2-V617F, were found in 70% of PV at diagnosis but never in ET.
Even though this mutation has been predicted to constitutively activate the JAK2 kinase, spontaneous phosphorylation of STAT5 does not seem to be a frequent finding in platelets from ET patients.
X-inactivation-based clonality analysis and quantitative JAK2V617F assessment reveal a strong association between clonality and JAK2V617F in PV but not ET/MMM, and identifies a subset of JAK2V617F-negative ET and MMM patients with clonal hematopoiesis.
The rate of thrombotic complications in JAK2-positive ET patients was significantly higher than that in wild-type ET patients and not statistically different from that in PV patients.
We conclude that megakaryocytes might be the predominant or even the exclusive lineage that acquires the JAK2(V617F) mutation in ET and that the JAK2(V617F) evolution to higher gene dosages represents a dynamic and complex process substantially involving megakaryocytes.
Accordingly, the WHO concept of two distinct entities, ET and prefibrotic IMF, does not seem to fit the model of JAK2-positive ET as part of a biological continuum of JAK2 V617F-positive chronic myeloproliferative disorders.
A single point mutation (Val617Phe) was identified in JAK2 in 42 (73.7%) of 57 patients with PV, 40 (58.8%) of 68 with ET, and eight (66.7%) of 12 with MMM.
We analyzed the expression of AGT, renin, AT2R1 and ACE genes in normal and bone marrows of PV and ET patients with the respect to the presence of V617F JAK2 mutation.
Retrospective data have identified JAK2(V617F) as a risk factor for thrombosis in ET, and have also shown a close association with abdominal vein thrombosis.
Finally, a significant correlation between JAK2 V617F mutational status and hematocrit (Ht), white blood cell and platelet counts in PV patients, and Ht values in ET cases, was observed by AS-PCR.
"The significance of bone marrow biopsy and JAK2V617F mutation in the differential diagnosis between the ""early"" prepolycythemic phase of polycythemia vera and essential thrombocythemia."