Although these data point to a likely role of AID in disease pathogenesis in CLL, the evidence for in vivo AID activity is scarce: typical AID off-target damage, such as somatic mutations of the BCL6 gene [41] or c-myc/IgH translocations [42] are very rare events in CLL and IgVH genes in AID-expressing CLL cells are frequently unmutated. This evidence concerns the gene MYC and B-cell chronic lymphocytic leukemia.