Therefore, at the end of an ALL induction in CML-BP, a discrepancy is often observed between low minimal residual disease (MRD) as assessed by immunoglobulin G heavy chain (IgH) or T cell receptor gene (TCR) rearrangement markers or flow cytometry (because of a preferential reduction in the lymphoid blast clone) and the still relatively high proportion of t(9;22) translocation–positive cells (of the still expanded BCR::ABL1-positive hematopoiesis) in florescence in situ hybridization (FISH) or transcript analysis [29]. This evidence concerns the gene ABL1 and acute lymphoblastic leukemia.