TABLE 1.

Summary to enhance the efficiency of CRISPR-mediated genome and epigenome editing.

Sr. no	Recommendation/Strategy
1	GC content of designed sgRNA must range from >30% to <70%
2	Target promoter region rather than exon or intron for gene disruption (if possible)
3	Prefer purine-rich spacer sequences (if possible)
4	Existence of secondary structure in sgRNA improves its processing and genome-editing capability
5	Truncating gRNA or adding extra guanines at its 5′end increases its specificity
6	Stabilize the gRNA with G-quadruplexe structure
7	Eliminate seed regions with UUU sequence
8	Chemically modify the gRNA
9	Substitute one of the nucleotides in the continuous stretch of four to six
10	Avoid constitutively higher expression level of sgRNA and Cas9 to prevent off-targeting
11	Select appropriate method to deliver CRISPR components
12	Avoid targeting heterochromatin region (if possible)
13	Inhibit NHEJ or stimulate HDR to increase the knock-in efficiency of transgene
14	Select appropriate type of donor-template and DNA-repair pathway
15	Use SpCas9MT-pDBD, paired nickase-Cas9 or dCas9-FokI to increase specificity
16	Prefer PAM-out orientation over PAM-in and D10A mutant over H840A
17	Use dead-guide or dead-Cas9 for epigenome editing
18	Recruit multiple activators by using modified guide and dCas9; combining dCas9 system with multipeptide array like SunTag; or using tripartite system to increase the efficiency of CRISPR activation
19	Modify dCas9 or sgRNA to recruit epigenetic modifiers at the target site