Prevalence of the JAK2 V617F Mutation in Patients with Non-Cardioembolic Stroke

This study attempted to clarify the prevalence and clinical characteristics of Janus kinase 2 V617F (JAK2) gene mutations in patients with cerebrovascular diseases.

We prospectively enrolled patients who were admitted to or referred to our department with cerebrovascular disease due to suspected major cerebral artery disease or small-vessel occlusion within 30 days of onset between January 1, 2021, and April 30, 2024, and who consented to undergo a JAK2 mutation analysis. We investigated the prevalence of JAK2 mutations based on the clinical subtype of stroke and the presence or absence of major cerebral artery disease. We also examined the clinical characteristics of patients with positive JAK2 mutation.

Among 316 consecutive inpatients (216 males; median age, 74 years old), JAK2 mutations were detected in 4 of 102 (3.9%) patients with large artery atherosclerosis, 2 of 101 patients (2.0%) with small-vessel occlusion, and 2 of 113 (1.8%) with other stroke subtypes. A multiple logistic regression analysis showed that patients with the positive JAK2 mutation had significantly higher hematocrit values (odds ratio [OR], 1.32; 95% confidence interval [CI], 1.07-1.62; p = 0.010), platelet counts (OR, 1.19; 95% CI, 1.07-1.31; p = 0.001), and thrombomodulin levels (OR, 1.08; 95% CI 1.01-1.15; p = 0.025) at admission than patients with the negative JAK2 mutation.

The frequency of JAK2 mutations is very low among patients with major cerebral artery diseases and small-vessel occlusion. The mechanisms underlying stroke onset in patients with the positive JAK2 mutation may involve factors beyond hematopoietic cells, such as endothelial dysfunction.