BCR and B-cell chronic lymphocytic leukemia: The frequency of AID-dependent mutations accumulated during BCR-inhibitor treatment was assessed by targeted sequencing covering up to 1000 bps upstream of the transcription starting site (TSS) of a panel of 27 genes (23 AID off-target genes; 4 non-target control genes—Supplementary Figure S1A) in paired pre- and post-treatment CLL samples.