Table 2.

Gene sizes of selected CRISPR-based tools in comparison with AAV vector genome size.

	Tool	Function	Gene size (kb)	Ref.
Within AAV packaging limit	SpCas9	Nuclease	4.2	Cong et al., 2013
	SaCas9	Nuclease	3.2	Ran et al., 2015
	PspCas13b	Ribonuclease	3.4	Cox et al., 2017
	RfxCas13d	Ribonuclease	2.9	Konermann et al., 2018
	dPspCas13b(tr)-ADARdd	RNA editing	4.1	Cox et al., 2017
	dSaCas9-KRAB	CRISPRi	3.6	Thakore et al., 2018
	FnCas12a	Nuclease	3.9	Zetsche et al., 2015a
	BhCas12b	Nuclease	3.3	Strecker et al., 2019
Beyond AAV packaging limit	BE4	Cytosine base editing	5.6	Komor et al., 2017
	ABE7.10	Adenine base editing	5.3	Gaudelli et al., 2017
	dSpCas9-TET1	Editing DNA methylation	6.4	Liu et al., 2016
	PE2	Prime editing	6.4	Anzalone et al., 2019
AAV vector component		Function	Size (kb)
ITR × 2		Vector genome rescue and replication during packaging; Packaging signal	0.3 total
Transgene cassette		Transgene expression	< 4.7