Abstract

Since the beginning of CRISPR/Cas9's use for genome‐editing, reports of off‐targets have caused concerns among users. Previous studies identified three main types of off‐targets. The first type of off‐targets are sequences at other 5’‐NGG‐3’ protospacer adjacent motifs (PAMs) that are identical or have a small number of mismatches or substitutions (Fu et al., 2013; Tsai et al., 2015). The second type of off‐targets are sequences at other 5’‐NGG‐3’ PAMs that have insertions or deletions compared to the gRNA spacer or the targeted DNA (Lin et al., 2014).

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