Off-target genomic DNA sites (Off-targets)

Off-target genomic DNA sites refer to unintended locations within the genome where gene-editing technologies, such as CRISPR-Cas9, TALENs, or ZFNs, bind and exert their activity. These sites often share significant sequence homology with the intended target, leading the editing machinery to recognize and modify them erroneously (Fu et al., 2013, Nature Biotechnology). The presence of off-target modifications poses a significant risk in clinical applications, as they can result in permanent mutations, large-scale chromosomal rearrangements, or the disruption of essential genes (Kosicki et al., 2018, Nature). Such events may lead to oncogenic transformation or other adverse cellular outcomes, making the identification and minimization of off-target activity a primary focus of safety assessments in gene therapy (Tsai et al., 2015, Nature Biotechnology). Advanced sequencing techniques like GUIDE-seq and CIRCLE-seq, along with computational algorithms, are currently used to predict and validate these sites to improve the precision of genomic medicines (Tsai et al., 2017, Nature Methods). Minimizing off-target effects is crucial for ensuring the long-term safety and regulatory approval of CRISPR-based therapeutics.

Other names

Off-target effectsOff-target mutationsNon-specific genomic bindingUnintended genomic modifications

Unintended binding and enzymatic modification (cleavage, deamination, or insertion/deletion) of DNA sequences that share homology with the intended target sequence.