Our studies reveal several important discoveries: (1) Ig loci translocations can be attributed to distinct mechanisms including AID- or RAG-associated DSBs in mature B cells; (2) AID-associated Igh translocations target oncogenes such as c-myc whereas RAG-associated translocations appear to involve random genomic loci; and (3) G1XP lymphomas harbor complicated genomes including segmental translocations, and exhibit a high level of ongoing DNA damage and clonal heterogeneity. Here, AICDA is linked to lymphoma.