JAK2 allele burden is correlated with a risk of venous but not arterial thrombosis.

BACKGROUND:Thrombosis is the main complication in myeloproliferative neoplasms (MPN). A JAK2V617F mutation has been shown to be a risk factor for thrombosis. The implication of other risk factors alongside a mutation allele burden needs to be clarified (Trifa et al., 2018; Borowczyk et al., 2015). OBJECTIVE:Our aim was to investigate the role of the JAK2 mutation allele burden in the risk of cardiovascular events (CVE) and/or venous thrombosis (VTE) in a cohort of patients with confirmed MPN, as well as in patients without confirmed MPN. METHODS:We restrospectively included all consecutive patients who were positive for JAK2V617F seen by our unit between December 2008 and September 2016. Inclusion criteria were a positive test for the JAK2V617F mutation, with at least 1% allele burden, with or without confirmed MPN. RESULTS:We included 239 patients of median age 71 years [60-81], followed-up for a median of 82.8 months [41.08-146.88]. For JAK2V617F positive patients having an allele burden superior to 50% the cumulative incidence of VTE was significantly higher than for those with an allele burden inferior to 50% (HR 3.11 95% CI [1.10-8.76] p = 0.031). The cumulative incidence of VTE was also higher in patients with obesity (HR 4.58 95% CI [1.33-15.8] p = 0.016). There was no significant association between a JAK2V617F allele burden and arterial thrombosis (manifesting as CVE). Previous VTE was also associated with a higher cumulative incidence of recurrence during follow-up HR 3.22 95% CI [1.17-8.81] p = 0.0231. CONCLUSION:We show that a JAK2V617F allele burden is associated with risk of VTE but not with CVE.