BCR and B-cell chronic lymphocytic leukemia: To verify the contribution of enhanced AID activity in the acquisition of increased mutational rate, we analyzed AID-mediated genomic mutations in blood samples from a cohort of patients with CLL (Figure 1B) treated with idelalisib (n = 8) or ibrutinib (n = 11) for about 12 months and a control cohort (n = 10) comprising patients with CLL who were not exposed to BCR pathway inhibitors but received standard-of-care chemotherapy.