JAK2 and Venous thrombosis: PV patients with venous thrombosis require systemic anticoagulation, in addition to cytoreductive drug therapy; we also consider adding low-dose aspirin in some instances in order to subvert the additional risk of arterial thrombosis, especially in the presence of JAK2 mutation or cardiovascular risk factors, as well as lessen the risk of recurrence of venous thrombosis [77].