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CRISPR

A bacterial immune system that researchers adapted into a programmable tool for cutting chosen DNA sequences.Source: NHGRISource: Barrangou et al., 2007Source: Jinek et al., 2012

Step 4 of 7ReadingTechnology or method

How it works

CRISPR is a pair of molecular scissors with a GPS. A guide RNA leads a protein to one spot in the DNA, where it makes a change.

A guide RNA matches the target sequence, and the Cas9 protein cuts the DNA there. The cell's repair systems then disable the gene or, with a template, write in a change. Newer base and prime editors change letters without cutting both strands.

Cas9 recognizes a short PAM sequence and uses RNA-DNA base pairing for specificity; off-target editing, delivery and immune responses remain active research topics. The first approved CRISPR therapy edits a patient's blood stem cells outside the body before returning them.

Used for
  • Research on gene function
  • An approved therapy for sickle cell disease
  • Crop and animal research

Safety and ethics

Editing a patient's body cells to treat disease is reviewed and regulated like other therapies. Heritable editing, which changes embryos so the change could pass to future generations, carries particular risks. The World Health Organization and the U.S. National Academies have published recommendations on how genome editing should be governed.
See it in the Biotechnology lab

How CRISPR connects

CRISPR comes from

  • Organism or group

    Bacteria

    Small single-celled organisms without a nucleus, found almost everywhere on Earth. Most bacteria in the human body are harmless, and some are helpful.

    Open in Microbe Lab

CRISPR uses

  • Level of life

    RNA

    A single-stranded relative of DNA. Messenger RNA carries a gene's instructions to ribosomes, and other RNAs help build proteins and control genes.

CRISPR makes possible

  • Technology or method

    Gene editing

    Making targeted changes to DNA in living cells. Newer base and prime editors change letters without cutting both strands.

    Emerging researchOpen in Biotech Lab

CRISPR raises questions of

  • Ethics and safety

    Genome editing governance

    Recommendations for overseeing human genome editing, which distinguish editing a patient's body cells from heritable editing.

Explore further

Open in Biotech LabIn the knowledge graphFind papers about CRISPR

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Sources & further reading

The explanations on this page are our own summaries of these sources. Follow a link to read the original; if anything here disagrees with it, the original wins. How we choose and check sources.

  3. A programmable dual-RNA-guided DNA endonuclease in adaptive bacterial immunity (opens the original in a new tab)

    Jinek M, Chylinski K, Fonfara I, et al. (2012). Science 337:816-821.

    Showed Cas9 can be programmed with guide RNA to cut chosen DNA sequences.

    Peer-reviewedPrimary research