JAK2 V617F mutational frequency in essential thrombocythemia associated with splanchnic or cerebral vein thrombosis

Splanchnic vein thrombosis (SVT) and chronic myeloproliferative neoplasms (MPN) are closely related. The JAK2 V617F mutation is a hall-mark of MPN but is present also in a relevant percentage of patients with SVT and without an overt chronic MPN. To investigate in patients with essential thrombocythemia (ET) the impact of this mutation on the risk of thrombosis in unusual sites (splanchnic or cerebral veins), we carried out a retrospective cohort study including 224 patients. One hundred forty-two patients (63%) had the mutation, and 68 had suffered either arterial thromboses (n = 39), venous thromboses in a common site (n = 12), or in the eye (n = 1), SVT (n = 13), or cerebral vein thrombosis (CVT; n = 3). All patients with SVT or CVT were <60 years of age: in this age range, the relative risk associated with the mutation, and adjusted for inherited thrombophilia was 1.88 (95%CI 1.32-2.69) for SVT, and 2.26 (95%CI 1.76-2.91) for CVT. No increase in the risk of a venous thrombosis in common sites was found in patients with the mutation. In conclusion, in ET the risk of venous thrombosis associated with the JAK2 V617F mutation preferentially targets splanchnic or cerebral veins in young patients.