PB and BM hematopoietic phenotype of germline JAKV617I. (A) Quantification of Lin-CD34+, phenotypic HSCs (CD45+Lin–CD34+CD38–CD90+CD45RA–), multipotent progenitors (MPPs; CD45+Lin–CD34+CD38–CD90–CD45RA–), common myeloid progenitors (CMPs; CD45+Lin–CD34+CD38+CD123+CD45RA–), granulocyte macrophage progenitors (GMPs; CD45+Lin–CD34+CD38+CD123+CD45RA+), and megakaryocyte erythroid progenitors (MEPs; CD45+Lin–CD34+CD38+CD123–CD45RA–) in the PB of normal controls (n = 4); JAK2V617I-positive samples (n = 4); patients with JAK2V617F-positive PV (n = 3); ET (n = 3), and myelofibrosis (n = 3). (B) Quantification of phenotypic HSCs, MPPs, CMPs, GMPs, and MEPs in the BM of normal controls (n = 8) and JAK2V617I-positive samples. (C) Numbers of BFU-E, CFU-GM, and CFU-GEMM in the BM of NC (n = 8) and JAK2V617I-positive (n = 4) cases. (D) Numbers and sizes of BM CFU-Mk in NC (n = 3) versus JAK2V617I (n = 4) patients. Error bars represent SEM. P values are shown if < .05.