Guiding Lights in Genome Editing for Inherited Retinal Disorders: Implications for Gene and Cell Therapy

Figure 5

Schematic representation of the CRISPR/Cas9 system. The Streptococcus pyogenes Cas9 nuclease, with a “NGG” protospacer adjacent motif (PAM) sequence, has been targeted to a 20-nucleotide guide sequence in a specific region in the genome (yellow). The gRNA is complementary to the non-PAM strand. The green line represents the gRNA scaffold, which complexes with the Cas9 nuclease (light blue) and directs it to the desired site to induce a DSB (red arrowheads) in the DNA. Cas9 mediates the DSB 3 bp upstream of the PAM sequence.