Genotyping of MDS progenitors. (A) Genotyping of CD34⁺CD38⁻ HSPC-derived CFCs. One hundred sorted bone marrow CD34⁺CD38⁻ cells were seeded in methylcellulose for CFCs of 7 MDS patients. Mutations identified in bulk BM MNCs were tracked in individual colonies. Clones are defined as colonies with the identical patterns of mutations. Proportions of clones derived from individual CD34⁺CD38⁻ cells and in CFCs derived from CD34⁺CD38⁻ cells are compared and represented by bars showing 95% CIs. (B) Immunophenotypic quantification of CMP, GMP, and MEP in the CD34⁺CD38⁺ cell compartment for 8 MDS patients and 1 cytapheresis used as control (see supplemental Methods). Density plots are shown and percentages of each studied cell population are indicated. (C) Genotyping of sorted CMPs, GMPs, and MEPs from 8 MDS patients by Sanger sequencing (200 cells per sample) or by NGS (UPN 21). Colored boxes correspond to detected mutation and open boxes for undetected mutation.