Table 2 Potential off-target sites with one to three mismatches to gRNA and their observed-targeting efficiencies.

From: Targeted and genome-wide sequencing reveal single nucleotide variations impacting specificity of Cas9 in human stem cells

Target and off-target indel frequencies
Number of mismatches Number of genomic sites Cas9 targeting efficiency
0 1 53.9%
1 0
2 0→1 36.7%
3 32 ~0.15% per site
  1. The variant allele of Chr5_OT represents the only site with only two mismatches to the gRNA and Cas9 target efficiency at this site was observed to be 36.7%, comparable with that of the target site (53.9%); the remaining sites with three mismatches were targeted by Cas9 with an average efficiency of ~0.15% (Supplementary Table 2) as measured by deep sequencing.