Endonuclease G initiates DNA rearrangements at the MLL breakpoint cluster upon replication stress.

MLL (myeloid/lymphoid or mixed-lineage leukemia) rearrangements are frequent in therapy-related and childhood acute leukemia, and are associated with poor prognosis. The majority of the rearrangements fall within a 7.3-kb MLL breakpoint cluster region (MLLbcr), particularly in a 0.