Table 2. Comparison of diversifying base edits in screening applications.

A summary of base editing screens. Selection strategy, cell type, delivery method and variant of base editor used are shown. The composition of the libraries and control libraries are described along with the number of identified variants or sgRNAs with phenotypes. A short summary of results for each screen is included.

Gene	Selection strategy	Cell type	Delivery	Base editor	Number of sgRNA	Number of significant hits/variants	Result	Reference
PSMB5	Bortezomib resistance	K562 cells	Lentiviral vector	CRISPR-X	143 targeting exons 705 safe-targeting controls	11 variants	Discovery of 2 known and 9 novel cancer drug resistance mutations	(Hess et al., 2016)
wtGFP	Fluorescence shift; cell sorting	K562 Cells	Plasmid nucleofection or Lentiviral Vector	CRISPR-X	4 targeting wtGFP 4 safe-targeting controls	1 variant	Recovery of known S65T substitution that changes fluorescence spectra to EGFP	(Hess et al., 2016)
BCR-ABL Kinase Domain	Imatinib resistance	K562 Cells	Plasmid nucleofection	TAM	16 targeting exon 6 3 targeting AAVS1	6 variants	Discovery of 1 known and 5 novel cancer drug resistance mutations	(Ma et al., 2016)
HPRT Puromycin mCherry	6TG selection, Puromycin selection, and mCherry FACS	HEK293T cells	Lentiviral vector	BE3	3 targeting HPRT 4 targeting Puromycin 4 targeting mCherry 16 controls	7 sgRNA	Demonstration of CRISPR-STOP approach in a functional screen	(Kuscu et al., 2017)(