What is the role of genetic testing in the workup of polycythemia vera (PV)?

Updated: Aug 20, 2019
  • Author: Srikanth Nagalla, MBBS, MS, FACP; Chief Editor: Koyamangalath Krishnan, MD, FRCP, FACP  more...
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Answer

JAK2 mutations also occur in about 60% of patients with essential thrombocythemia. PV is mainly related to JAK2 mutations, whereas a wider mutational spectrum is detected in essential thrombocythemia (ET) with mutations in JAK2, the thrombopoietin (TPO) receptor (MPL), and the calreticulin (CALR) genes. [14]

In patients who are positive for JAK2 and whose hemoglobin/hematocrit level is diagnostically equivocal (ie, as in "masked" PV), bone marrow examination is necessary to distinguish the two conditions. [15]  Masked PV includes both early forms of PV as well as a distinct form marked by male predominance, a more frequent history of arterial thrombosis and thrombocytosis, and significantly higher rates of progression to myelofibrosis and acute leukemia and inferior survival. [16]

If the JAK2 V617F mutation is absent but the Epo level is low, then testing for JAK2 exon 12 and 13 mutations would be helpful for making a diagnosis of PV in the 2-3% of PV patients who are negative for JAK2 V617F mutation. Patients who are negative for JAK2 mutations and have a normal or high Epo level have secondary erythrocytosis.


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