Born from bacterial immune memory
In 1987 researchers at Osaka University spotted strange repeating sequences in E. coli DNA without knowing what they did. Spanish microbiologist Francisco Mojica named them CRISPR (clustered regularly interspaced short palindromic repeats). In 2005 he showed that the spacers between repeats came from viral DNA. Bacteria were storing "mugshots" of past invaders so they could cut them up if they returned. In 2012 Jennifer Doudna and Emmanuelle Charpentier turned this system into programmable scissors that cut chosen DNA in a test tube, earning the 2020 Nobel Prize in Chemistry. Around the same time, Feng Zhang adapted it to human cells, which set off a bitter patent fight.
How it works
Scientists design a guide RNA of about 20 letters matching the target gene. The guide leads Cas9 to that exact spot, where the enzyme cuts both DNA strands. When the cell repairs the break, the gene is either disabled or replaced with a supplied healthy sequence. Because it's far cheaper, faster, and more precise than older methods, CRISPR became a standard tool in biology labs. Newer base editing and prime editing change single letters without a double-strand cut.
Therapies and ethics
In 2023 the US and UK approved Casgevy, the first CRISPR therapy, for sickle cell disease and beta thalassemia. CRISPR is also used for drought-tolerant crops and non-browning mushrooms, and it has been adapted for COVID diagnostics. In 2018 Chinese scientist He Jiankui announced twins born from embryos he had edited to resist HIV. He was condemned worldwide and sentenced to three years in prison. Most countries ban heritable germline editing, and off-target cuts remain a safety concern. The work has also revived the nature vs nurture debate over how much genes determine.
FAQ
- Can CRISPR make people taller or smarter?
- No. Height and intelligence involve thousands of genes plus environment, and such edits are banned anyway.
- Is CRISPR used to treat patients today?
- Yes. Casgevy is approved for sickle cell disease and beta thalassemia, and more trials are underway.
Sources reviewed: 2026-10-26
References
- Jinek, M., Chylinski, K., Fonfara, I., Hauer, M., Doudna, J. A., & Charpentier, E. (2012). A programmable dual-RNA–guided DNA endonuclease in adaptive bacterial immunity. Science, 337, 816–821.
- Mojica, F. J. M., et al. (2005). Intervening sequences of regularly spaced prokaryotic repeats derive from foreign genetic elements. J Mol Evol, 60, 174–182.
- U.S. FDA. (2023). FDA approves first gene therapies to treat sickle cell disease (Casgevy).