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Updated: Sep 13, 2025
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Published on: March 16, 2022
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Gene editing and CRISPR-dependent homology-mediated end joining
Brian L Ruis1, Anja K Bielinsky2, Eric A Hendrickson3
1Department of Medicine, University of Virginia, Charlottesville, VA, USA.
Experimental & Molecular Medicine
|July 31, 2025
Summary
Gene editing enables precise genetic modifications for gene knockouts and gene therapy. The CRISPR-Cas9 system has revolutionized gene editing, making it accessible and efficient for research and therapeutic applications.
Area of Science:
- Molecular Biology
- Genetics
- Biotechnology
Background:
- Gene editing involves intentional modification of genetic material in living cells.
- Two primary applications are gene inactivation (knockouts) and gene correction (knock-ins) for therapeutic purposes.
- Different repair pathways, nonhomologous end joining (NHEJ) and homology-dependent repair (HDR), are involved in these processes.
Purpose of the Study:
- To explain the mechanisms and applications of gene editing.
- To highlight the historical challenges and recent advancements in gene editing technologies.
- To emphasize the impact of CRISPR-Cas9 on the accessibility and efficiency of gene editing.
Main Methods:
- Gene knockouts are typically achieved by inducing double-stranded DNA breaks, leading to error-prone nonhomologous end joining (NHEJ) and frameshift mutations.
- Gene knock-ins utilize homology-dependent repair (HDR) to integrate new genetic information via donor DNA.
- The development and application of CRISPR-Cas9 technology for precise gene targeting.
Main Results:
- CRISPR-Cas9 has overcome previous limitations in gene editing efficiency and accessibility.
- Gene editing is now feasible in a wide range of model organisms and human somatic cells.
- The technology facilitates directed mutagenesis, directed evolution, and advancements in gene therapy.
Conclusions:
- Gene editing, particularly with CRISPR-Cas9, has democratized genetic modification.
- This technology heralds a new era for biological research and the development of novel therapeutics.
- CRISPR-Cas9 offers unprecedented ease and efficiency for gene knockouts and knock-ins.
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