Staining patterns after therapy. Representative examples of (A) “normal” and (B) “MRD” staining patterns, as well as (C) overt clinical relapse. CD34⁺CD38⁻ cells are shown by ALDH versus side scatter (SSC). (A) An AML patient (patient 17) with normal cytogenetics, in durable CR exhibiting the “normal” pattern with no detectable CD34⁺CD38⁻ALDH^int population. The comparison diagnostic pattern for this patient is shown in Figure 1D. (B) An AML patient (patient 1) with Inv16 AML, demonstrating the “MRD” pattern while still in CR; the circled CD34⁺CD38⁻ALDH^int population was 95% leukemic by FISH. The comparison diagnostic pattern is shown in Figure 1C. (C) A patient (patient 9) with t(8;21) AML, in overt relapse resembling the original diagnostic pattern (shown in Figure 1B). The percentages of CD34⁺CD38⁻ cells composed of the CD34⁺CD38⁻ALDH^int and CD34⁺CD38⁻ALDH^high populations are listed on each dot plot.