The difference in one sentence
Ordinary CRISPR cuts through both strands of DNA and relies on the cell to repair the break — which is reliable for breaking a gene and unreliable for fixing one. Base editing never makes that cut. It chemically converts one letter into another while the helix stays intact, which is far better for correcting a single-letter mistake but cannot insert or delete anything.
| Aspect | CRISPR-Cas9 | Base editing |
|---|---|---|
| Cuts both strands? | Yes | No — one strand nicked at most |
| How the change is made | The cell's repair machinery makes it | A chemical enzyme makes it directly |
| What it can do | Disable a gene reliably; correct only with a template, in dividing cells | Change C↔T and A↔G; cannot insert or delete |
| Best at | Knocking a gene out | Correcting a single-letter mistake |
| Main risk | Large deletions and chromosomal rearrangements at the cut | Bystander edits within the small working window |
| Works in non-dividing cells? | For knockouts, yes; for precise correction, no | Yes |
| Clinical status | One approved medicine | Pivotal trials; no approval yet |
Sources
- Nature (Komor et al.) · 2016
Programmable editing of a target base in genomic DNA without double-stranded DNA cleavage ↗