High-efficiency induction of t(9;11) chromosomal translocations. (A) Schematic summary of serial dilution experiment to assess the efficiency of creating t(9;11) translocations by CRISPR/Cas9 gene editing. Immediately after CRISPR/Cas9 treatment, electroporated cells were serially diluted into control electroporated cells (without Cas9 or sgRNAs) to a total of 20 000 cells. The serially diluted cells were cultured for 14 days, and genomic DNAs were extracted for PCR. PCR amplification of genomic DNA (200-ng template) shows genomic junctions for MLL-AF9 (B; blue arrowheads) and AF9-MLL (C; red arrowheads). *, nonspecific bands. (D) Sanger sequencing results for PCR amplicons from 4 cultures initiated with 200 CRISPR/Cas9-treated cells. ▼, Cas9 cutting position.