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What is CRISPR?

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Quick answer

CRISPR is a gene-editing tool that lets scientists cut DNA at a precise location to disable, repair, or replace a gene. Adapted from a bacterial immune system, it is faster, cheaper, and more accurate than older methods, and is already being used to treat genetic diseases.

Key things to understand

  1. A guide RNA steers the Cas9 'scissors' protein to a matching DNA sequence.
  2. Cas9 cuts both strands there; the cell's repair can disable a gene or paste in a new one.
  3. It originated as bacteria's defense for slicing up invading virus DNA.
  4. Already approved to treat sickle-cell disease and being tested for cancers, blindness, and more.
  5. Editing embryos ('germline') is hugely controversial because changes pass to future generations.

People also ask

What does CRISPR stand for?
Clustered Regularly Interspaced Short Palindromic Repeats — the repeated DNA patterns in bacteria that inspired the tool.
Is CRISPR safe to use in people?
Treating body cells (not embryos) has produced real cures, but risks like off-target cuts mean it's used carefully under strict trials and oversight.
Can CRISPR create 'designer babies'?
Editing embryos is technically possible but banned or tightly restricted in most countries for safety and ethical reasons.