ZFNs and TALENs are the preceding genome editing techniques to …show more content…
An additional advantage of CRISPR is its ability to target multiple targets at once. In early 2013, heterologous expression of the CRISPR-Cas9 system and all of its parts was demonstrated in mammalian cells. The modified bacterial system was also able to insert genes at various target locations in the mammalian genome by expressing a multiple target spacer array (Cong et al., 2013). The system was expressed in mammalian cells with varying combinations of codon optimized Cas9 (spCas9). spCas9 used a modified version of RNase