Cytogenetic alterations are seen in MDS HSCs. (A) Colony formation assay using sorted Lin⁻CD34⁺CD38⁻ cells from 4 MDS patients and 2 healthy controls. Data are mean ± SD for colonies arising from BFU-E and CFU-GM per 5000 plated cells. (B-C) Microscopic image of MDS patient-derived, sorted Lin⁻CD34⁺CD38⁻ cells grown in the semisolid culture for 12 days. DiffQuick staining of cytospun cells. Scale bar represents 50 μm. (D-E) FISH analysis of day 12 colonies from 2 patients with MDS. (F) Sorted HSCs from 1 patient with MDS showing monosomy of chromosome 7 in the majority of cells and 1 cell (yellow arrow) with both copies of chromosome 7 (red probe for 7q31 and centromeric green probe). (G) Mean percentages and SEM of abnormal karyotypic clones in lower-risk MDS HSC and progenitor compartments. Gray bar represents the results obtained from whole BM from the clinical diagnostic laboratory. *P < .05 (2-tailed t test).