BCR and precursor B-cell acute lymphoblastic leukemia: BCR sequencing concurred closely with qPCR transcript levels (red/green versus blue lines, Figure 1a), demonstrating strong correlations between the percentage of clonotypic B-ALL BCRs and qPCR T/C ratios (R2 values>0.87, Supplementary Table S3), while B-ALL clonotypic BCR sequences were detected in all qPCR-positive samples.