We conclude that MLL breakage and religation in the topoisomerase-sensitive bcr, leading to MLL rearrangements (deletions, insertions) in clinical samples, may occur not only after exposure to
topoisomerase II inhibitors but also during spontaneous
apoptosis of clinical samples. The MLL gene is sensitive to site-specific cleavage in the t-AML-associated bcr during the initial stages of
apoptosis owing to a colocalized scaffold attachment region.7 Religation of cleaved MLL, implicating an at least partially intact
DNA repair, has however never been observed during spontaneous
apoptosis in clinical samples. Our observation suggests that the rapid processing of samples (less than 24 h) is a prerequisite to discern therapy-induced MLL rearrangements from those that are associated with spontaneous
apoptosis ...