General Information About Chronic Myeloproliferative Disorders
The chronic myeloproliferative disorders consist of chronic myelogenous leukemia, polycythemia vera (p. vera), primary myelofibrosis, essential thrombocythemia, chronic neutrophilic leukemia, and chronic eosinophilic leukemia. All of these disorders involve dysregulation at the multipotent hematopoietic stem cell (CD34), with one or more of the following shared features:
Overproduction of one or several blood elements with dominance of a transformed clone.
Hypercellular marrow/marrow fibrosis.
Thrombotic and/or hemorrhagic diatheses.
Extramedullary hematopoiesis (liver/spleen).
Transformation to acute leukemia.
Overlapping clinical features.
Patients with p. vera and essential thrombocythemia have marked increases of red blood cell and platelet production, respectively. Treatment is directed at reducing the excessive numbers of blood cells. Both p. vera and essential thrombocythemia can develop a spent phase late in their courses that resembles primary myelofibrosis with cytopenias and marrow hypoplasia and fibrosis.[1,2,3] A specific point mutation in one copy of the Janus kinase 2 gene (JAK2), a cytoplasmic tyrosine kinase, on chromosome 9, which causes increased proliferation and survival of hematopoietic precursors in vitro, has been identified in most patients with p. vera, essential thrombocythemia, and idiopathic myelofibrosis.[4,5,6,7,8,9] Researchers are pursuing specific targeting of this aberrant protein.
For more information, U.S. residents may call the National Cancer Institute's (NCI's) Cancer Information Service toll-free at 1-800-4-CANCER (1-800-422-6237) Monday through Friday from 8:00 a.m. to 8:00 p.m., Eastern Time. A trained Cancer Information Specialist is available to answer your questions.
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Schafer AI: Bleeding and thrombosis in the myeloproliferative disorders. Blood 64 (1): 1-12, 1984.
Barosi G: Myelofibrosis with myeloid metaplasia: diagnostic definition and prognostic classification for clinical studies and treatment guidelines. J Clin Oncol 17 (9): 2954-70, 1999.
Tefferi A: Myelofibrosis with myeloid metaplasia. N Engl J Med 342 (17): 1255-65, 2000.
Kralovics R, Passamonti F, Buser AS, et al.: A gain-of-function mutation of JAK2 in myeloproliferative disorders. N Engl J Med 352 (17): 1779-90, 2005.
Baxter EJ, Scott LM, Campbell PJ, et al.: Acquired mutation of the tyrosine kinase JAK2 in human myeloproliferative disorders. Lancet 365 (9464): 1054-61, 2005 Mar 19-25.
James C, Ugo V, Le Couédic JP, et al.: A unique clonal JAK2 mutation leading to constitutive signalling causes polycythaemia vera. Nature 434 (7037): 1144-8, 2005.
Levine RL, Wadleigh M, Cools J, et al.: Activating mutation in the tyrosine kinase JAK2 in polycythemia vera, essential thrombocythemia, and myeloid metaplasia with myelofibrosis. Cancer Cell 7 (4): 387-97, 2005.
Scott LM, Tong W, Levine RL, et al.: JAK2 exon 12 mutations in polycythemia vera and idiopathic erythrocytosis. N Engl J Med 356 (5): 459-68, 2007.
Campbell PJ, Green AR: The myeloproliferative disorders. N Engl J Med 355 (23): 2452-66, 2006.