[Diagnosis and therapy of polycythemia vera in the era of JAK2]

This review gives an overview on relevant topics of pathogenesis and diagnosis of polycythemia vera (PV). The presently available treatment options in PV are discussed and recommendations for the clinical management are given.The JAK2V617F mutation, a point mutation in the tyrosine kinase gene JAK2 (Janus Kinase 2), has emerged as a central feature in the pathogenesis of the myeloproliferative neoplasms (MPN). Subsequently, the identification of several other mutated genes in MPN has shown that the pathogenesis is complex and that the JAK2V617F mutation is a critical, but not the only step leading to the uncontrolled proliferation in MPN including PV.The diagnostic criteria of PV have been revised in 2008 and include the JAK2V617F mutation as one of the two major criteria of the disease. This molecular diagnostic marker proves the clonality and facilitates the diagnosis of early and uncertain cases which remained sometimes undiagnosed in the past.Main treatment aims are the reduction of thromboembolic events and the minimization of the risk of myelofibrosis and of acute leukemia. PV patients with low risk of vascular complications should be treated with phlebotomy and low dose acetylsalicylic acid. High risk patients should receive cytoreductive therapy with hydroxyurea or interferon alpha. Studies with JAK inhibitors are presently ongoing.