CRISPR/Cas9 technology is rapidly evolving in an unprecedented way in the field of gene editing, with its core components: gRNA and Cas9 endonuclease. Cas9 targets the specific sequence in the genome under gRNA guidance and cleaves the DNA duplex at the target site to form a DSB nick. This, in turn, triggers DNA repair mechanisms: non-homologous end-linking (NHEJ) or homologous directed repair (HDR). The NHEJ pathway introduces mutations at the DSB site, and in the presence of homologous sequences, the HDR pathway introduces gene knockin at the DSB site.
