A powerful new gene-editing technology called CRISPR has enormous potential to treat human diseases but the ability to tinker with genes can also be controversial. Editing genes can mean removing or replacing an existing gene, switching a gene on or off, or inserting a new gene altogether. Whatever the aim, the first step is always to find the stretch of DNA that codes for the gene and grab hold of it, so a cut or tweak can be made.
CRISPR not only finds the target gene and locks on, it also delivers an enzyme that cuts the DNA. And it does all this with unprecedented accuracy. The reason it’s able to manage this precision double act is because CRISPR is made of ribonucleic acid (RNA) — a molecule that can be tailor-made to perfectly match a sequence of DNA or to bind to a protein. CRISPR RNA does both jobs — one end is custom-made to match the target gene’s DNA sequence, and the other end binds to a DNA-cutting enzyme, or nuclease.
Here we explain what CRISPR is and how it works.