Consistently, PI3Kδ inhibitors enhanced AID expression and translocation frequency to IGH and other sites in human chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL) cell lines, and, finally, in patients treated with idelalisib, but not ibrutinib, there is increased somatic hypermutation in the genome. The gene discussed is AICDA; the disease is mantle cell lymphoma.