crisper

CRISPR refers to a family of DNA sequences in bacteria and archaea that form part of an adaptive immune system. In the most widely used form, CRISPR-associated (Cas) nucleases such as Cas9 act as programmable DNA scissors guided by RNA.

A spacer-derived guide RNA matches a target DNA sequence next to a PAM, enabling Cas to cleave. The cell repairs the break using non-homologous end joining or homology-directed repair, allowing knockouts or precise edits if a template is provided.

Since its adaptation for genome editing in 2012–2013, CRISPR has transformed genetics research. Applications span functional genomics, disease modeling, agriculture, and experimental gene therapy, among others.

Variants include Cas12a (Cpf1), and tools that alter gene expression without cutting DNA, such as CRISPR interference (CRISPRi) and CRISPR activation (CRISPRa). Base editing and prime editing enable targeted, efficient edits with fewer double-strand breaks.

Delivery methods include viral vectors, ribonucleoprotein complexes, and non-viral delivery. Limitations include off-target effects, mosaicism, and ethical/regulatory considerations that vary by country.

The field continues to evolve with ongoing research into safety, efficiency, and applications.