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.
Acute lymphoblastic leukemia (ALL) is the most common type of cancer in children. It affects certain cells in the immune system, called B cells and T cells. ALL usually affects B cells in children.
It's natural to feel worried when you learn your child has acute lymphoblastic leukemia, but keep in mind that almost all children can be cured of this disease.
B-cell ALL makes your child more likely to get infections, because he doesn't have the protection of those B cells.
The disease starts...
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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.
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September 04, 2014
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