The definitive guide to gene editing.
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Technology · Gene regulation

CRISPRi (gene silencing)

Parks a disabled CRISPR protein on a gene to block it from being read, turning it down without changing it.

Research tool no cuttingresearchregulation
Laboratory research Demonstrated in the laboratory. There is no treatment in or near the clinic for this use.

Simple explanation

The same disabled CRISPR protein, but instead of a megaphone it carries a muffler — or simply sits in the way. The machinery that reads the gene runs into it and stops. Nothing is cut and nothing is rewritten; the gene is just made quiet.

Go deeper

CRISPR interference uses dCas9, usually fused to a KRAB repressor domain, targeted to a promoter or early coding region. It sterically blocks transcription initiation or elongation and, via KRAB, recruits repressive chromatin machinery. Effects are typically reversible when dCas9 expression stops, distinguishing it from epigenetic editors designed for durable silencing.

Changing how loudly a gene speaks — without editing it CRISPRa — turn it up dead Cas9 carries an activator; the gene is read more often the DNA letters are untouched CRISPRi — turn it down a repressor blocks the machinery that reads the gene reversible — stop supplying it and the gene returns Because nothing is cut, there is no permanent change to inherit — and no double-strand break to go wrong. The flip side: the effect lasts only as long as the tool is present.
This is the clearest counter-example to "gene editing always means changing DNA" — these tools deliberately leave the sequence alone.

Why it beats knocking the gene out, for research

A knockout is all or nothing and permanent. CRISPRi gives partial, tunable, reversible knockdown, which is closer to how most drugs behave and much more informative when you want to know what a gene does at reduced rather than zero function — particularly for essential genes, where a knockout simply kills the cell and tells you nothing.

Why it beats knocking the gene out, for research
A disabled CRISPR clamp obstructing the machinery that reads a gene. Illustration generated for The CRISPR Atlas — a visual aid, not a photograph or a literal depiction of molecular structure.

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Educational information only This page is a reference, not medical advice. Research and regulatory status change; check the last-updated date above and confirm anything important against the primary sources listed.