Incidence rates of major arterial/venous thrombosis for JAK2, type 1/type 1-like CALR, type 2/type 2-like CALR, MPL-mutated and TN cases were 16%/13%, 7%/5%, 7%/2%, 13%/7%, and 18%/12%, respectively. The gene discussed is MPL; the disease is deep vein thrombosis.