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In oncology, polycythemia vera (PV) is an uncommon myeloproliferative neoplasm in which the bone marrow makes too many red blood cells. [1] The majority of cases [2] are caused by mutations in the JAK2 gene, most commonly resulting in a single amino acid change in its protein product from valine to phenylalanine at position 617.
Polycythemia vera (PV) is associated most often with the JAK2 V617F mutation greater than 95% of cases, whereas the remainder has a JAK2 exon 12 mutations. High hemoglobin or hematocrit counts are required, as is a bone marrow examination showing "prominent erythroid , granulocytic and megakaryocytic proliferation with pleomorphic, mature ...
Janus kinase 2 (commonly called JAK2) is a non-receptor tyrosine kinase.It is a member of the Janus kinase family and has been implicated in signaling by members of the type II cytokine receptor family (e.g. interferon receptors), the GM-CSF receptor family (IL-3R, IL-5R and GM-CSF-R), the gp130 receptor family (e.g., IL-6R), and the single chain receptors (e.g. Epo-R, Tpo-R, GH-R, PRL-R).
These mutations are not specific to myelofibrosis, but are observed in other myeloproliferative neoplasms, specifically polycythemia vera and essential thrombocythemia. [ 3 ] The JAK2 protein is mutated giving risk to a variant protein with an amino acid substitution commonly referred to as V617F; the mutation causing this variant is found in ...
The most common JAK2 mutation is V617F which is the replacement of a valine amino acid with phenylalanine amino acid at the 617 position, hence the name V617F. This mutation results in the JAK2 protein constantly being turned on, which leads to the overproduction of abnormal blood cells, in ET it is platelets or megakaryocytes.
A hallmark of polycythemia vera is an elevated hematocrit, with Hct > 55% seen in 83% of cases. [19] A somatic (non-hereditary) mutation (V617F) in the JAK2 gene, also present in other myeloproliferative disorders, is found in 95% of cases. [20]
Janus kinase (JAK) is a family of intracellular, non-receptor tyrosine kinases that transduce cytokine-mediated signals via the JAK-STAT pathway.They were initially named "just another kinase" 1 and 2 (since they were just two of many discoveries in a PCR-based screen of kinases), [1] but were ultimately published as "Janus kinase".
Nearly one-third of patients have a myeloproliferative disorder (e.g. polycythemia vera [6] or primary thrombocytosis), most commonly due to a Janus kinase 2 (JAK2) gene mutation. [1] Oral contraceptive use or pregnancy are other non-inherited tendencies for thrombosis. [citation needed]