The Association Between Janus Kinase 2 and Factor V Leiden Mutations and Thrombotic Complications in Patients With Myeloproliferative Disorders: A Study From Saudi Arabia.

Background The Janus kinase 2 (JAK2) V617F mutations are related to increased thrombotic risk in patients with myeloproliferative disorders (MPDs). However, little is known about whether inherited thrombophilia represents an additive risk factor in mutated subjects. We addressed the association between combined mutations of JAK2 and factor V Leiden (FVL) and thrombotic complications in Saudi Arabian patients with MPDs. Methods We studied 60 patients with MPDs, 32 with polycythemia vera (PV), 24 with essential thrombocythemia (ET), and four with primary myelofibrosis (PMF). All patients were examined for JAK2 V617F and FVL mutations. Results The study included 50 (83.3%) males and 10 (16.7%) females, with a mean age of 44.23 ± 11.32 years. JAK2 was found positive among all (100%) of the studied patients. Thirty-eight patients out of 60 (63.3%) had thrombotic events. FVL was found positive in 12 (20%) patients. The patients with JAK2 and FVL mutations had a higher incidence of thrombotic events (11/38, 28.9%) than those with JAK2 but without FVL mutations (1/22, 4.5%). The relative risk ratios for increased risk for having thrombotic events were 2.1 (95% confidence interval (95% CI): 1.2-3.8, p=0.03) and 4.3 (95% CI: 2.1-9.5, p<0.001) for patients with mutations alone, and those with both JAK2 and FVL mutations, respectively. Conclusions In the present study of patients with MPDs from Saudi Arabia, JAK2 mutations were found among all the studied patients, and FVL mutations were encountered in 20% of patients. The patients with both JAK2 and FVL mutations had a higher incidence of thrombotic events than those with JAK2 but without FVL mutations. The relative risk ratios for increased risk for thrombotic events among patients with MPDs were 2.1 and 4.3 for patients with JAK2 mutations alone and those with JAK2 and FVL mutations, respectively. Further larger prospective studies are warranted.