Table 5.

Overview on the validity assessment of all studies and the reason for validation.

Validity assessment	Number of studies	Reason for validity assessment outcomes	Number of analyzed potential off-target sites
High validity	326	All study validity assessment criteria were rated as “Yes”	High validity: 2,267
Medium validity	44	Some potential off-target sequences were followed by a PAM (n = 28) Information are considerably incomplete (n = 15) Only some potential off-target sequences show at least one mismatch (n = 7)	Medium/High validity: 4,149 Medium/Low validity: 154
Low validity	72	No on-target mutation was induced (n = 27) Reference genome has not been fully sequenced/sequencing error when analyzing potential off-target sequences (n = 7) Potential off-target sequences were not followed by a PAM (n = 15) All potential off-target sequences have no mismatch (n = 5) No information is provided (n = 23) Overexpression of the sgRNA/Cas9 complex (n = 1)	Low validity: 197
Unclear validity	26	Lacking sufficient information to judge (n = 26)	Unclear validity: 170