Important Note

It is now becoming evident that more than 90% of patients with conventionally-defined polycythemina vera (pv) carry the somatic JAK2 V617F mutation. However, the specific mutation is also found in other classical and atypical myeloproliferative neoplasms (MPN), albeit to a lesser extent. In contrast, JAK2 V617F has not been reported in patients with either reactive myeloproliferation or lymphoid disorders. Therefore, mutation screening for JAK2 V617F can be considered as a myeloid-specific clonality assay and it is diagnostically most useful in the evaluation of polycythemia.