Genomic DNA (Cas12 target site) (Cas12 target DNA)

Genomic DNA at designed Cas12 guide-RNA target sites refers to specific sequences within the genome targeted for modification by the CRISPR-Cas12 (formerly Cpf1) endonuclease system. Cas12 is a Class 2 Type V CRISPR-Cas system that utilizes a single CRISPR RNA (crRNA) to recognize a target DNA sequence adjacent to a T-rich protospacer adjacent motif (PAM), typically 5'-TTTV-3' [Zetsche et al., 2015, Cell]. Unlike the more common Cas9, Cas12 generates a staggered double-strand break with 4-5 nucleotide overhangs, which can facilitate specific DNA repair pathways like homology-directed repair (HDR) [Paul and Montoya, 2020, Biomedicines]. In a therapeutic context, these DNA sites are the direct substrates for gene editing drugs designed to correct mutations, disrupt pathogenic genes, or insert therapeutic sequences. For example, the investigational therapy EDIT-301 targets the promoter regions of the HBG1 and HBG2 genes in genomic DNA to induce fetal hemoglobin production for the treatment of sickle cell disease [Editas Medicine, 2024]. The precision of targeting these sites is critical, as unintended "off-target" editing at similar sequences elsewhere in the genome can lead to safety concerns such as oncogenic mutations or chromosomal instability [Fu et al., 2013, Nature Biotechnology]. Therapeutic delivery often involves ex vivo modification of hematopoietic stem cells or in vivo delivery via viral vectors or lipid nanoparticles. Overall, these genomic sites represent the fundamental point of intervention for Cas12-based genetic medicines.

Other names

Cpf1 target siteCRISPR-Cas12 target sequenceProtospacer sequence (Cas12)Type V CRISPR target

RNA-guided site-specific DNA cleavage followed by cellular DNA repair (NHEJ or HDR)