What is CRISPR gene editing?
CRISPR gene editing is a technology that lets scientists change DNA at a chosen location in a living cell. A guide molecule made of RNA leads a cutting protein, most often Cas9, to a matching DNA sequence. The genetic code can then be altered there.
Also known as: CRISPR-Cas9, CRISPR genome editing, genetic scissors
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How it works
CRISPR stands for clustered regularly interspaced short palindromic repeats, the National Human Genome Research Institute says. It says the tool was adapted from genome editing systems found naturally in bacteria. There it is part of an immune defense that cuts up viral DNA, the Royal Swedish Academy of Sciences says. That comes from its account of the 2020 Nobel Prize in Chemistry.
That prize went to Emmanuelle Charpentier and Jennifer Doudna. In 2012 they showed this machinery could be made to cut DNA at a chosen site. The academy says they fused two RNA molecules into a single guide RNA whose code is set to match the target. The guide leads the Cas9 protein there, and Cas9 cuts. The cell's own DNA repair is used to rewrite the sequence.
Newer versions avoid cutting both DNA strands. Base editing changes single DNA letters, the Innovative Genomics Institute (IGI) noted in a March 2026 review of clinical trials. Prime editing can likewise correct a mutation, it said.
From lab tool to medicine
In December 2023 the U.S. Food and Drug Administration (FDA) approved Casgevy for sickle cell disease in patients 12 and older. It called Casgevy the first FDA-approved therapy to use CRISPR/Cas9. A patient's blood stem cells are edited, then transplanted back.
In May 2025 the National Institutes of Health reported on a CRISPR therapy for one infant with the rare genetic disease CPS1 deficiency. It said a team at Children's Hospital of Philadelphia and the University of Pennsylvania built it, taking six months from diagnosis to treatment.
Where things stand in 2026
On February 23, 2026, the FDA issued draft guidance setting out a "plausible mechanism" framework. It is for approving individualized therapies, including genome editing, when patient numbers are too small for randomized trials. The FDA still labeled it a draft as of October 6, 2026.
Casgevy is priced at $2.2 million and 64 patients received it in 2025, the IGI review says. It also described reduced venture funding and layoffs at some CRISPR-focused companies.
AI has been used to design editors. In a July 2025 Nature paper, researchers designed editors using large language models and a dataset of more than 1 million CRISPR operons, or gene clusters. All declared ties to the company Profluent. They reported that several editors matched or exceeded standard Cas9 in activity and specificity. They released one, OpenCRISPR-1.
Sources
- CRISPR, National Human Genome Research Institute (NHGRI)
- The Nobel Prize in Chemistry 2020 - Popular information, The Royal Swedish Academy of Sciences, via NobelPrize.org
- CRISPR Clinical Trials: A 2026 Update, Innovative Genomics Institute (IGI)
- FDA Approves First Gene Therapies to Treat Patients with Sickle Cell Disease, U.S. Food and Drug Administration (FDA)
- Infant with rare, incurable disease is first to successfully receive personalized gene therapy treatment, National Institutes of Health (NIH)
- FDA Launches Framework for Accelerating Development of Individualized Therapies for Ultra-Rare Diseases, U.S. Food and Drug Administration (FDA)
- Considerations for the use of the Plausible Mechanism Framework to Develop Individualized Therapies that Target Specific Genetic Conditions with Known Biological Cause (draft guidance), U.S. Food and Drug Administration (FDA)
- Design of highly functional genome editors by modelling CRISPR–Cas sequences, Nature (Ruffolo et al.)
