Influence of the JAK2 V617F Mutation and Inherited Thrombophilia on the Thrombotic Risk among Patients with Myeloproliferative Disorders.

BACKGROUND A number of studies showed that the JAK2 V617F mutation increases the thrombotic risk in patients with myeloproliferative disorders (MPN) while others did not reveal this correlation, and it is unknown whether inherited thrombophilia is an additive risk factor in mutated subjects. Our aim was to clarify the contribution of JAK2 V617F to a hypercoagulable state, as well as its interaction with other thrombophilic factors in patients with thrombosis and myeloproliferative disorders. METHOD We studied 192 patients with myeloproliferative disorders, 90 with Essential thrombocytemia (ET), 42 with Polycythemia vera (PV) and 60 with Primary or idiopathic myelofibrosis (PMI). From these patients a subgroup of only 62 patients underwent laboratory screening for thrombophilia. RESULTS The JAK2 V617F mutation was present in 62.8% patients with myeloproliferative disorders, 97.6% with PV, 54.5 % with ET and 53.44% patients with PMI. The mutated patients had a relative risk (RR) for thrombosis at any time of 2.94 in comparison with "wild-type" patients which was 0.93; in those patients having both the mutation and thrombophilia the RR was 3.56 (95% CI 2.41-7.34) compared to patients with neither the mutation nor thrombophilia, suggesting an additive interaction between the two risk factors. CONCLUSION In patients with myeloproliferatives neoplasias, the thrombotic risk is higher in the JAK2 V617F-mutated subgroup and it is further increased by the presence of inherited thrombophilia (especially by the presence of mutated F V Leiden and lupus anticoagulant).