Based on these pharmacodynamic (PD) data, a b.i.d. aspirin regimen was recently recommended for patients with PV deemed at “high” thrombotic risk based on Janus Kinase 2 (JAK2) V617F mutation allelic burden, leukocytosis, age greater than 60 years, and/or previous thrombosis.5, 11. This evidence concerns the gene JAK2 and acquired polycythemia vera.