Spleen (SPL) HSPCs in the anemia erythroid response. (A) Colonies derived from single phenotypic HSCs/MPPs from control spleen (Ctrl SPL; n = 234 single cells from 3 donors) and spleens of patients with hereditary spherocytosis (HS; n = 198 single cells from 2 donors) seeded into medium supporting My, Ery, Meg, and lymphoid (measured by growth of natural killer cell [NK]) differentiation (see Methods). Mean ± standard deviation is shown. (B) CD19^–CD34⁺ HSPCs (n = 9 939 cells) from 2 patients with HS were sequenced using the 10X scRNA-seq platform and were integrated with control spleen data (same as in Figure 2). Uniform Manifold Approximation and Projections and cluster annotation of the HSPC landscape are shown in supplemental Figure 6B-C. Volcano plot shows the differentially expressed genes (false discovery rate <0.05, log-fold change >0.2) between transcriptionally defined HSCs/MPPs from control and HS spleens. Genes associated with Ery lineage commitment are shown in red. (C) Ratio of early megakaryocyte/erythroid/mast cell/basophil (MEMB) to early My progenitors in control and HS spleens. Median ± 95% confidence interval is shown. (D) Normalized estimated cellular output from early to late progenitors of the MEMB (left) and the My (right) branch calculated as for Figure 3D-E (see Methods). Gray line indicates theoretical exponential expansion; vertical error bars indicate the range observed in the different tissues; and horizontal error bars indicate the standard deviation of the estimated number of divisions for each expansion stage. Control spleens are the same as in Figure 3D-E. Undiff, undifferentiated.