cGAS (cyclic GMP-AMP synthase) belongs to the nucleotidyl transferase family. It consists of a nucleotide-binding domain and a catalytic domain. cGAS is mainly located in the cytoplasm. When cells are infected or damaged by viruses, it can recognize and bind double-stranded DNA, trigger signaling pathways, activate STING protein by synthesizing guanosine diphosphate (cGAMP), and then activate interferons and inflammatory factors. production, promoting anti-viral and anti-tumor immune responses. cGAS gene mutations or dysregulated expression are associated with a variety of diseases, such as autoimmune diseases, tumors, and neurodegenerative diseases.