The changes in the platelet and neutrophil counts in 4 PV patients treated only with phlebotomy to maintain the hematocrit <45% in men and <42% in women. (A) Patient 1. A 57-year-old woman with PV for 39 years with a JAK2^V617F VAF of 67%, who still requires periodic phlebotomies. (B) Patient 2. A 67-year-old woman with PV for 37 years with a JAK2^V617F VAF of 50%, who still requires periodic phlebotomies. (C) Patient 3. A 77-year-old man with PV for 16 years with a JAK2^V617F VAF of 67%, who does not require phlebotomy. (D) Patient 4. A 76-year-old woman with PV for 19 years with a JAK2^V617F VAF of 77%, who does not require phlebotomy.