Prevalence of definite antiphospholipid syndrome in carriers of the JAK2 V617F mutation.

Introduction: Patients with Philadelphia-negative myeloproliferative neoplasms (MPNs), particularly those carrying the JAK2 ^V617F mutation, are at increased risk of thrombosis. While an association of MPNs with autoimmune disorders has been established, the prevalence of inherited or acquired thrombophilias in JAK2 ^V617F -positive patients remains obscure. We therefore investigated the coincidence of the JAK2 ^V617F mutation with additional thrombogenic risk factors.
Methods: In a retrospective study, we analyzed all patients referred for thrombophilia work-up between 01/2011 and 08/2019, in whom additional JAK2 ^V617F mutation analysis was performed because of thromboembolic events that were recurrent, atypically located and/or associated with abnormal blood counts.
Results: Of 472 tested patients, 49 (10.4%) were JAK2 ^V617F -positive. While the frequency of inherited thrombophilias (factor V Leiden and prothrombin G20210A mutation, deficiency of antithrombin, protein C, protein S) was not different between the two groups, the prevalence of definite antiphospholipid syndrome (APS), mostly associated with a moderate- or high-risk antibody profile, was significantly higher in patients with (22.4%) than in those without (8.4%) JAK2 ^V617F mutation (p < 0.01). All evaluable JAK2 ^V617F -positive patients with APS were subsequently diagnosed with MPN. In patients with JAK2 ^V617F mutation, presence of concomitant APS was associated with a significantly younger age (49 ± 14 vs. 60 ± 15 years) at the time of thrombophilia work-up (p < 0.05).
Conclusion: We found a significant association between JAK2 ^V617F -positive MPN and definite APS. The presence of concomitant APS in patients carrying the JAK2 ^V617F mutation may lead to earlier manifestation of thromboembolic events and may warrant more aggressive antithrombotic treatment strategies to prevent recurrence.
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