Impact of JAK2V617F mutation on thrombosis and myeloid transformation in essential thrombocythemia: a multivariate analysis by Cox regression in 141 patients

Assessing the thrombotic risk of patients with essential thrombocythemia in the genomic era

The molecular characterization of myeloproliferative neoplasms, including essential thrombocythemia (ET), has enabled deeper understanding of their pathogenesis. A driver lesion, namely, Janus kinase (JAK)2V617F, calreticulin (CALR) or myeloproliferative leukemia (MPL) gene mutation can be identified in the vast majority of patients. Each of these mutations is associated with distinct clinical features and may modulate the patients' clinical course, risk of complications, including vascular events, and survival. JAK2V617F appears to be a risk-modifying mutation and has been shown to increase the likelihood of thrombotic events in patients with ET across studies. As such, it has been included in prognostic models and its presence may influence treatment decisions. The association of CALR and MPL mutations with the incidence of vascular events has been less clear. Even more limited information is available on the contribution of additional non-driver lesions to the thrombotic risk. In this review we discuss the available evidence on the role of recurrent mutations in the risk of thrombotic complications in patients with ET and how these mutations weigh into modern prognostic scores.

The impact of JAK2V617F mutation on different types of thrombosis risk in patients with essential thrombocythemia: a meta-analysis

To assess the effect of JAK2V617F on different thrombotic risks in essential thrombocythemia (ET) patients, we identified eligible studies from several databases including Pubmed, Embase, and Cochrane Central Register of Controlled Trials (up to November 2014). Twenty-two studies of 2922 ET patients were included in exploring the relationship between JAK2V617F and the risk of thrombosis. Compared to JAK2V617F-negative ET patients, JAK2V617F-positive ET patients had higher odd risks (ORs) of arterial thrombosis [OR = 2.59 (1.84-3.65)] and venous thrombosis [OR = 2.10 (1.53-2.88)]. The JAK2V617F-positive group was also more prone to increased risk of microcirculatory disturbances [OR = 1.50 (0.97-2.32)]. Moreover, JAK2V617F may indicate increased risk of either arterial [OR = 1.71 (1.22-2.39)] or venous thrombosis [OR = 2.90 (1.54-5.46)] before diagnosis of ET. During follow-up, JAK2V617F might not be related to arterial thrombosis [OR = 1.90 (0.90-2.08)], but rather venous thrombosis [OR = 1.95 (1.08-3.53)]. In conclusion, JAK2V617F increased the risk of arterial and venous thrombosis in ET patients, while understanding its role in microcirculatory disturbances will require further studies.