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last update : 05-03-2009
Symbol MPD
Location 9q24.1
Name Ph1-negative myeloproliferative disorders, JAK2 mutated
Other name(s) including polycythemia vera (PV), essential thrombocytosis (ET) and primary myelofibrosis (PMF)
Corresponding gene JAK2
Main clinical features
  • clonal expansion of myeloid cells
  • splenomegaly, thrombosis, bone marrow fibrosis, extramedullary hematopoiesis, and leukemic transformation
  • increased and clustered megakaryocytes in ET and PV, increased granulopoiesis in PV and PMF, and increased erythropoiesis in PV
  • Genetic determination somatic
    Function/system disorder hematology
    Type malignancy
    Gene product
    Name janus family of non-receptor tyrosine-kinases; JAK2 is important in myeloid cell proliferation and differenciation
    Gene mutationChromosome rearrangementEffectComments
    missense   abnormal protein/gain of function somatic activating mutation JAK2V617F in 95 percent of patients with PV and in 50 percent of patients with ET and PMF
        abnormal protein/gain of function somatic exon 12 mutations
    other     a common haplotype preferentially acquires JAK2(V617F) and confers an increase risk of myeloproliferative neoplasms
    Remark(s) activating the JAK-STAT pathway ; activating mutations in the thrombopoietin receptor MPL are found in JAK2-negative PMF and ET patients ; the susceptibility haplotype could account for fully half the MPD risk attributable to inherited factors