Examples of detecting MRD with “different-from-normal approach” applied to myeloblast population. (A) AML patient undergoing allogeneic stem cell transplant with no prior flow cytometric data available to identify diagnostic LAIP; however, pretransplant bone marrow CD34⁺ myeloblasts (defined by gating using CD34⁺/CD117⁺/CD45/SSC/FSC parameters) include a clearly aberrant CD34⁺CD33⁺CD56⁺ leukemic population and therefore are MRD-positive (0.05% of BM-nucleated cells). This patient relapsed with the same aberrant phenotype. (B) Examples of 2 AML patients (AML-1, AML-2) monitored for MRD during chemotherapy using data overlay with a control sample to detect “different-from-normal” blast subpopulations in CD117⁺ myeloblasts (defined by gating using CD117⁺/CD45/ SSC/FSC parameters). Green, CD117⁺ myeloblasts of control bone marrow; red, CD117⁺ myeloblasts of patient’s bone marrow; blue, emerging aberrant leukemic subpopulation within empty space; empty space, region in which there are very few or no normal cells. (AML-1) CD34 vs HLADR plots shown of CD117⁺ blasts. Presentation sample was hemodilute with no definite LAIP (other markers not shown). Postcourse 1 sample had a small number of cells in an empty space (CD34⁺HLADRlow, in blue) but categorized as insufficient to define as MRD without a diagnostic LAIP; however, the postcourse 2 sample had obvious MRD within the same empty space. (AML-2) CD33 vs CD13 plot shown of CD117⁺ blasts. Change in leukemic immunophenotype with MRD postcourse 3 from an emerging new aberrant subpopulation in an empty space (CD33⁺CD13low, in blue). This patient relapsed with the same aberrant phenotype but the diagnostic LAIPs were not present (including from other markers not shown).