Molecular and cytogenetic features of MLL-AF9–rearranged cells induced by genome editing. (A) Representative PCR to detect MLL-AF9 (left) and AF9-MLL (right) translocation breakpoints in gene-edited cells at day 27 of culture (samples 1 and 2). (B) Data shown are a composite alignment of PCR products from multiple experiments (days 7-14 of culture) showing a variety of distinct translocations. Arrowheads indicate the sequence of long-term–survived clones. (C) FISH analysis using an MLL break-apart probe was performed on genome-edited cells maintained in culture for over 50 days. A representative image is shown. Arrows indicate the split signals of the break-apart probe indicating MLL translocation. (D) Representative metaphase chromosomes from karyotype analysis of genome-edited cells shows a balanced t(9;11) chromosomal translocation.