Genomic DNA at the guide-RNA–specified locus (Target DNA locus)

Genomic DNA at the guide-RNA–specified locus refers to the specific sequence within the host genome targeted for modification by CRISPR-Cas systems. This target is defined by the base-pairing complementarity between a synthetic guide RNA (gRNA) and the genomic DNA, typically requiring a nearby protospacer adjacent motif (PAM) for recognition by the Cas nuclease [1]. Once the complex binds, it facilitates precise molecular changes such as double-strand breaks, single-base substitutions, or epigenetic modifications [2]. This approach is used therapeutically to correct mutations in genetic diseases, disrupt viral DNA, or engineer immune cells for cancer therapy [3]. For example, exagamglogene autotemcel targets the BCL11A enhancer to induce fetal hemoglobin in patients with sickle cell disease [4]. However, the potential for off-target effects at similar genomic sequences remains a primary safety concern in the clinical application of these drugs [5]. Monitoring for unintended genomic rearrangements and the long-term stability of the edited locus is essential for patient safety. The specificity of this target is the cornerstone of modern precision medicine, allowing for the direct correction of the underlying genetic causes of disease.

Other names

CRISPR target siteProtospacergRNA target sequenceGenomic target locusTarget DNA sequence

The mechanism involves the formation of a ribonucleoprotein (RNP) complex between a Cas nuclease and a guide RNA, which scans the genome for a protospacer adjacent motif (PAM). Upon PAM recognition, the gRNA hybridizes with the target DNA locus via Watson-Crick base pairing, triggering site-specific cleavage or chemical modification to alter the genetic sequence or its expression [1, 3].