JAK2 ^V617F Mutation in Essential Thrombocythemia.

Background: Essential thrombocythemia (ET) is thought to reflect transformation of a multipotent hematopoietic stem cell, but its molecular pathogenesis has remained obscure. But tyrosine kinase, especially Janus kinase 2 (JAK2) has been implicated in myeloproliferative disorders other than chronic myeloid leukemia. We investigated the incidence and its correlation with other clinicopathologic variables of JAK2 mutation in patients with ET and reactive thrombocytosis (RT).

Method: JAK2 mutation analysis, using allele-specific polymerase chain reaction, was undertaken on genomic DNA from bone marrow aspirates of 24 patients with ET and peripheral blood in 36 patients with RT.

Results: JAK2 mutation was detected in 11 patients (46%) among the 24 patients with ET and was not found in 36 patients with RT. In patients with ET, older age and leukocytosis were related with JAK2 mutation without statistical significance (p=0.172 and 0.094, respectively). But this mutation was not correlated with sex, hemoglobin, platelet count, splenomegaly, increased cellularity of bone marrow, bone marrow fibrosis and vascular complications.

Conclusions: The current observation strengthens the specific association between JAK2 mutation and ET. At the diagnosis of ET, identification of JAK2 mutation should be incorporated in foundation for new approaches.