Table 6.

Platforms for gene editing (table [37]) adapted from

Platform	Details
Zinc finger nucleases (ZFN) and transcription activator like effector nucleases (TALEN)	ZFNs and TALENs are fusions between arrays of zinc fingers or TALEN DNA-binding domains and the dimerization-dependent FokI nuclease domain They are directed to site-specific targets of genomic DNA and create a dsDNA break at the site Both require extensive engineering and optimization for each new target
Clustered regularly interspersed short palindromic repeats/Crispr-associated protein 9 (CRISPR/Cas9)	CRISPR/Cas9 is an RNA-guided endonuclease A 23 nucleotide long RNA linked to the CRISPR-domain (gRNA), guides the CRISPR-Cas9 to find the complementary protospacer DNA target in a genome where it cuts the double-stranded DNA precisely 3 base pairs upstream of a PAM (protospacer adjacent motif)
Broken DNA ends generated by these are repaired either by: Non-homologous end joining (NHEJ) resulting in small insertion/deletions (indels) to disrupt target allele], or by homology directed repair (HDR) to precisely replace desired nucleotides with delivery of the homologous DNA template