Introduction. The development of class II, type VI bacterial clustered, regularly interspaced, short palindromic repeat CRISPR-Cas13 systems for mammalian cells has continued to expand the field of genome engineering1,2,3,4. The Cas13 nuclease can bind to specific RNAs; when the target RNA complements at least 20 to 30 nucleotides of a CRISPR RNA (crRNA), the Cas13-crRNA complex is activated and the higher eukaryotes and prokaryotes nucleotide-binding domain (HEPN domain) undertakes RNA cl...