CRISPR-associated protein 9–single guide RNA complex (Cas9–sgRNA complex)

The **CRISPR-associated protein 9–single guide RNA (Cas9–sgRNA) complex** is a programmable genome editing system originally derived from the adaptive immune defense of bacteria, now an essential biotechnological tool for targeted genetic modification across multiple organisms. The complex works when a chimeric single guide RNA (sgRNA) directs the Cas9 endonuclease to a user-defined DNA sequence adjacent to a protospacer adjacent motif (PAM). Upon recognition, Cas9 produces a double-stranded DNA break at the target site, which is repaired by cellular DNA repair mechanisms, leading to targeted gene disruptions (knockouts) or precise corrections (knockins) depending on the repair template provided[1][3][4][6][7][8]. Modifications of Cas9 (e.g., dead Cas9/dCas9) allow DNA binding without cleavage, enabling transcriptional regulation or epigenome modification[1][2][7]. While the Cas9–sgRNA complex is not itself a classical therapeutic target (like a receptor or enzyme), it is central to genome editing therapies for diseases including genetic disorders, cancers, and infectious diseases, but raises concerns regarding off-target effects and immune response[3][7]. **Incorrectness rationale:** This entity describes a *genome editing tool* (the Cas9–sgRNA complex), not a biological target such as a receptor, enzyme, or channel typically engaged by drugs. It is a synthetic ribonucleoprotein complex used as a programmable DNA endonuclease system for genome modification, making it a genome engineering reagent rather than a canonical therapeutic target[4][7].

Other names

CRISPR/Cas9Cas9–guide RNA complexCas9-sgRNASpCas9–sgRNACas9 RNP

Not applicable (acts as a programmable nuclease guided by sgRNA, not modulated by classical drugs)