Kaplan-Meier analysis of the time to developing hematologic and clinical outcome events in JAK2V617F mutated PMF patients categorized according to quartiles of mutated allele burden. The plots show time to anemia, leukopenia, large splenomegaly, and leukemic transformation in the 4 quartiles of JAK2V617F allele burden. P values are shown inside each box. Quartiles of V617F allele burden were as follows: first, 1% to 25%; second, greater than 25% to 50%; third, greater than 50% to 75%; fourth, greater than 75% to 100%.