CRISPRCas9genomredigering

CRISPR-Cas9 is a genome editing technology derived from a bacterial immune system. It uses the Cas9 nuclease guided by a short RNA molecule to recognize a specific DNA sequence adjacent to a PAM and to introduce a double-strand break. The cell then repairs the break through non-homologous end joining, which often disrupts the target gene, or through homology-directed repair when a DNA template is provided, enabling precise sequence changes.

Development and impact: The system was adapted for programmable genome editing in mammalian cells in the early 2010s and rapidly became a widely used tool in biology due to its relative simplicity, efficiency, and versatility compared with earlier methods.

Applications: CRISPR-Cas9 supports functional genomics studies, creation of model organisms, biotechnology and agricultural improvements, and exploratory therapeutic research. In medicine, ex vivo editing of patient cells is a prominent area of clinical investigation, with potential applications ranging from inherited diseases to cancer immunotherapy.

Delivery and design: Researchers deliver Cas9 and guide RNA as DNA, messenger RNA, or as ribonucleoprotein complexes. Common delivery methods include viral vectors, lipid nanoparticles, and electroporation. Design considerations include target site selection, the presence of a PAM sequence, and potential off-target effects, as well as concerns about mosaicism in edited tissues.

Ethical and regulatory context: Human genome editing, particularly of germline cells, raises ethical questions and is subject to varying regulatory frameworks across countries, emphasizing safety, consent, and social implications.

Future directions: Ongoing advances aim to improve specificity, expand the range of editable sequences with alternative Cas enzymes, and develop new editing modalities such as base editing and prime editing to reduce unintended changes.