Detecting the JAK2 V617F mutation in fresh and ‘historic’ blood and bone marrow

The detection of the Janus kinase 2 (JAK2) mutation V617F has become fundamental in the differential diagnosis of myeloproliferative syndromes (MPS). While this mutation is common in bcr/abl translocation-negative (bcr/abl-) MPS, that is, in polycythemia vera (>90% of cases),1 essential thrombocythemia and chronic idiopathic myelofibrosis (50–70% of cases each),1 and occurs in 70% of cases of 'refractory anemia with ringed sideroblasts and thrombocytosis',2, 3 it is consistently absent in chronic myelogenous leukemia4 and a rare exception in acute myeloid leukemias, chronic myelomonocytic leukemias and myelodysplastic syndromes.5