Patients with PV with the JAK2 V617F allele burden of >75% exhibited higher thrombotic risk than those with <25% (p = 0.03) [52] and higher risk of venous thromboembolism (VTE) when their JAK2 allele burden is >20%, but not for arterial thrombosis [53]. Here, JAK2 is linked to acquired polycythemia vera.