Off-target mutagenesis is one potential consequence of genome editing. Whole genome sequencing of several mutant iPSC lines generated through application of this protocol did not reveal a substantial burden of off-target mutation, although each of the 6 cell lines that underwent whole genome sequencing did acquire 10–15 off-target mutations each, of which 1–3 were attributable to gRNA-related Cas9 activity. Interestingly, the mutation sites were in some cases poorly predicted by current algorithms.
