are used to create a double stranded break in the dna at a specific locus in the genome. the zfn editing complex consists of a zinc finger protein (zfp) and a restriction enzyme cleavage domain. the znp domain can be altered to change the dna sequence that the restriction enzyme cuts, and this cleavage event initiates cellular repair processes, similar to that of crispr/cas9 dna editing. compared to crispr/cas9, the therapeutic applications of this technology are limited, due to the extensive engineering required to make each zfn specific to the desired sequence.