Characterizations of the unintended mutations and identification of a sequence signature related to APOBEC activity. a Fold change of each type of mutation in base-edited iPSC clones as compared to control clones. A fold change is calculated by dividing the number of one type of mutation detected in one clone by the average number of that mutation type (indicated on x-axis) detected in three control clones N1, N2 and N3. Source data are provided in the Source Data file. b Sequence logos of the conserved bases around the C>T mutations in each iPSC clone after inducible base editor expression. The mutated C is shown at position 0. The overall height of each stack indicates the sequence conservation at that position, while the height of symbols within the stack indicates the relative frequency of each nucleic acid at that position22. Sequence logos from position −5 to position 25 are shown in Supplementary Fig. 3. c Sequence logos of the conserved bases around the C>T mutations in iPSC clones edited by transient transfection. d Sequence logos of the conserved bases around the C->G mutations in iPSC clones that each has more than 40 detected C:G->G:C transversions.