JAK2 Negative Polycythemia Vera.

Polycythemia vera (PV) is a stem cell disorder, characterized as a panhyperplastic, malignant, and neoplastic marrow disorder. Several reasons suggest that a mutation on the Janus kinase-2 gene (JAK2) is the most probable candidate gene involved in PV pathogenesis, as JAK2 is directly involved in intracellular signaling, following its exposure to cytokines, to which PV progenitor cells display hypersensitivity. A recurrent unique acquired clonal mutation in JAK2 was found in most patients with PV and other myeloproliferative diseases (MPDs). A female patient of age 50 years, presented with hemiplegia, diplopia, and had a consistent rise in hemoglobin and hematocrit. Serum Erythropoietin (Epo) was decreased. JAK2 mutation analysis was found to be negative. A diagnosis of polycythemia vera was made on the basis of the British Committee for Standards in Hematology (BCSH) guidelines.