Immature platelets are increased in JAK2V617F⁺ ET and PV patients. Figure shows data on immature platelet fraction (IPF) values according to disease type, JAK2V617F mutation, and hydroxyurea (HU) treatment. Both ET and PV patients positive for the JAK2V617F mutation and not receiving HU showed significantly higher IPF count compared with control subjects (P < .05). In addition, JAK2V617F⁺ ET and PV patients not treated with HU showed significantly higher IPF count compared with JAK2V617F⁻ and HU-treated JAK2V617F⁺ and JAK2V617F⁻ patients not treated with HU. *P < .05 compared with controls. Modified with permission from Panova-Noeva et al.²⁴