What Is CRISPR?

CRISPR-Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats) was originally a bacterial immune defence against viruses. Scientists Jennifer Doudna and Emmanuelle Charpentier adapted it in 2012 into a molecular tool: a guide RNA directs the Cas9 enzyme to a specific DNA location, where it makes a precise cut. The cell repair machinery then either disables the gene or inserts a new sequence. CRISPR is faster, cheaper, and more accurate than earlier gene-editing methods and is being used in medicine (sickle-cell disease therapy), agriculture (disease-resistant crops), and basic research.