HomeGenetics UnderstandingGenomicresearchWhat are genome editing and CRISPR-Cas9?
Back to Genomicresearch
What are genome editing and CRISPR-Cas9?
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Genomicresearch

What are genome editing and CRISPR‑Cas9?

Genome editing lets scientists add, remove, or alter DNA, and the CRISPR‑Cas9 system makes this possible faster, cheaper, and more accurately than earlier methods.

Overview

Genome editing (also called gene editing) is a group of technologies that give scientists the ability to change an organism's DNA. These technologies allow genetic material to be added, removed, or altered at particular locations in the genome.

How CRISPR‑Cas9 Works

The CRISPR‑Cas9 system was adapted from a naturally occurring bacterial immune defense. Bacteria capture short pieces of viral DNA and insert them into their own genome as CRISPR arrays. When the same virus attacks again, the bacteria transcribe RNA from these arrays that matches the viral DNA, bind the Cas9 enzyme, and cut the viral genome, disabling the virus.

Researchers mimic this process by designing a short “guide” RNA that binds a specific DNA sequence in a target cell. The guide RNA is paired with the Cas9 enzyme (or a similar enzyme such as Cpf1). Once inside the cell, the guide directs Cas9 to cut the DNA at the intended location. The cell’s own repair machinery then adds, deletes, or replaces genetic material.

Current and Potential Applications

Genome editing is being used in research labs on cells and animal models to understand disease mechanisms. Clinical research is exploring its safety and efficacy for a wide variety of conditions, including:

  • Single‑gene disorders such as cystic fibrosis, hemophilia, and sickle cell disease
  • Complex diseases such as cancer, heart disease, mental illness, and HIV infection

While promising, the technology is still under investigation before routine therapeutic use in people.

Ethical Considerations

Most genome‑editing efforts target somatic cells—cells other than eggs or sperm—so changes affect only the treated individual and are not passed to future generations. Editing of germline cells (egg, sperm, or embryos) could be inherited, raising ethical questions about enhancement of normal traits (e.g., height or intelligence). Because of these concerns, germline and embryo editing are currently illegal in the United States and many other countries.

Further Reading

Scientific journal articles

  • Boti MA, Athanasopoulou K, Adamopoulos PG, et al. Recent Advances in Genome‑Engineering Strategies. Genes (Basel). 2023;14(1):129. doi:10.3390/genes14010129. PMID: 36672870.
  • Gostimskaya I. CRISPR‑Cas9: A History of Its Discovery and Ethical Considerations of Its Use in Genome Editing. Biochemistry (Mosc). 2022;87(8):777‑788. doi:10.1134/S0006297922080090. PMID: 36171658.
  • Sharma G, Sharma AR, Bhattacharya M, et al. CRISPR‑Cas9: A Preclinical and Clinical Perspective for the Treatment of Human Diseases. Molecular Therapy. 2021;29(2):571‑586. doi:10.1016/j.ymthe.2020.09.028. PMID: 33238136.
  • Zheng R, Zhang L, Parvin R, et al. Progress and Perspective of CRISPR‑Cas9 Technology in Translational Medicine. Advanced Science. 2023;10(25):e2300195. doi:10.1002/advs.202300195. PMID: 37356052.

Additional resources

The National Human Genome Research Institute (NHGRI) offers the following:

  • What is genome editing?
  • How is genome editing used?

Questions and answers about CRISPR are available from the Broad Institute.

The American Society of Gene and Cell Therapy (ASGCT) provides information about gene editing.

PubMed maintains a list of articles about genome editing and CRISPR‑Cas9.

ClinicalTrials.gov lists studies using genome‑editing technologies.

Related Topics in the Genomic Research Chapter

  • What are single nucleotide polymorphisms (SNPs)?
  • What are genome‑wide association studies?
  • What is pharmacogenomics?
  • What are genome editing and CRISPR‑Cas9?

Frequently Asked Questions

Germline editing raises concerns about unintended heritable changes, equity of access, consent of future generations, and the possibility of “designer babies.” Many countries have strict regulations or bans on germline editing for reproductive purposes, and international guidelines emphasize caution and robust ethical oversight.
Researchers use whole‑genome sequencing and targeted deep‑sequencing of predicted off‑target sites before and after treatment. They also employ computational tools that predict off‑target sites and monitor patients for unintended mutations or changes in cell function through regular blood tests and imaging.
Clinical trials are underway for several single‑gene disorders such as sickle cell disease, beta‑thalassemia, and certain forms of inherited blindness. Early studies also target cancers (e.g., CAR‑T cell therapies using CRISPR to enhance immune cell function) and viral infections like HIV, where the virus’s DNA is edited or removed from infected cells.
The design phase can take a few weeks, followed by laboratory validation that may take another month. Manufacturing the therapeutic vector (often an AAV or lipid nanoparticle) and ensuring GMP compliance adds several months. Clinical delivery to a patient usually occurs within 6–12 months from initial design, depending on regulatory approvals and trial phase.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

kontakt@hittavard.se

Ⓒ 2024. Alla rättigheter förbehålls av juxt ab

Sök
Om ossVillkor och policyVanliga frågorKontakta oss