Impaired hematopoietic differentiation of patients’ cells. (A) Expression of early erythroid maturation genes in MEP cells from healthy donors and patients. Cells encircled in a black box (y location > 15 and x location > 15) in the left panel were analyzed for expression of early erythroid maturation genes; the right panel shows frequency of cells with different expression levels of erythroid genes. Healthy donor 4 was not included because of a limited cell number included in the black square. ETP, earliest thymic progenitor; GMP, granulocyte-monocyte progenitor; MLP, multilymphoid progenitor; ProB, pro–B cell. (B) Correlation of erythroid gene expression levels with hemoglobin concentration. Patient 2 had a hemoglobin concentration of 10.9 g/dL at time of marrow sample collection, which decreased to 9 g/dL 3 months later. (C) CD38 expression levels in cells of patient 4. CD38⁻, CD34⁺CD38⁻ cells; CD38⁺/HSC, CD34⁺CD38⁺ cells within the HSC/MLP population (x location < 10 on minimum spanning tree ); and CD38⁺/MEP, CD34⁺CD38⁺ cells within the MEP population (x location ≥ 10). (D-E) Expression levels of HSC genes or AML genes in cells of patient 4. *P < .05, **P < .01, and ***P < .001.