Genome editing has powerful applications in research, healthcare, and agriculture. However, the range of possible molecular events resulting from genome editing has been underestimated and the technology remains unpredictable on, and away from, the target locus. This has considerable impact in providing a safe approach for therapeutic genome editing, agriculture, and other applications. This opinion article discusses how to anticipate and detect those editing events by a combination of assays to capture all possible genomic changes. It also discusses strategies for preventing unwanted effects, critical to appraise the benefit or risk associated with the use of the technology. Anticipating and verifying the result of genome editing are essential for the success for all applications.
Genome Editing: A Transformative TechnologyThe application of genome editing is transforming agriculture, biomedical research, and healthcare. The many proposed purposes include the generation of more productive or robust crops and farm animals, animal hosts for the production of tissues for graft purposes and therapies that use ex vivo or somatic tissue engineering [1-3]. The promise of applicability is turning into reality, as illustrated by the first nonrandomized Phase I clinical trial i in which the use of clustered regularly interspaced short palindromic repeats (CRISPR)-engineered T cells was recently found to be safe [4]. To date, N20 Phase I/II human clinical trials are underway for a broad range of diseases, including cancers, β-thalassemia, sickle cell disease, and Duchenne muscular dystrophy (summarized and discussed in [1,5]).Genome editing is generally based on either zinc finger nucleases [6], transcription activator-like effector nucleases [7], or the CRISPR/CRISPR-associated (Cas) system (see Glossary) [8]. These molecules act by inducing a double-stranded cut in a specific DNA sequence, which results in a genetic alteration as the gap is being repaired. In the clinic, the initial applications aim for deletions of genomic DNA intervals and do not yet involve precision at the nucleotide level; thus, these can be executed through the sole delivery of a genome-editing nuclease. However, for more precise editing, such as the generation of point mutations or more intricate changes, or even accurate deletion of a genomic segment, single-or double-stranded DNA templates are also delivered, together with the nucleases, to direct the repair to result in a given sequence by homology directed repair (HDR) [9][10][11] or nonhomologous end-joining [12]. Base editors [13] and prime editors [14] are alternative strategies for more precise editing. Overall, the range of genome editing tools is ever increasing and their transformative potential across a range of fields of application is immense.
Genome Editing: A Disruptive but Still Erratic TechnologyThe safety of genome-editing technologies is just as critical as their efficiency for their successful application in health or agriculture. Common to all fields of application are the ri...