DLGAP1 (DLG associated protein 1) encodes a guanylate kinase-associated protein (GKAP) that functions as a postsynaptic scaffold protein in neuronal cells, playing a critical role in glutamatergic synaptic transmission 1. The protein contains molecular adaptor activity and localizes to postsynaptic specializations and the plasma membrane, where it facilitates protein-protein interactions essential for chemical synaptic transmission [GO annotations supported by structural studies]. Mechanistically, DLGAP1 is involved in organizing postsynaptic density complexes through protein-binding interactions at glutamatergic synapses [UniProt, GO annotations]. The DLGAP1 gene contains regulatory polymorphisms; specifically, the rs11081062 SNP shows significant association with obsessive-compulsive disorder (OCD), with CT and TT genotypes conferring increased risk for sexual/religious obsessions and counting compulsions 1. Beyond its synaptic function, DLGAP1 has unexpected disease relevance through antisense RNA transcripts. DLGAP1-AS1 and DLGAP1-AS2 function as oncogenic long non-coding RNAs upregulated across multiple cancers including lung, colorectal, breast, and glioblastoma, where they promote cell proliferation, invasion, and drug resistance 234. In non-small cell lung cancer, miR-30a-5p directly targets DLGAP1 mRNA, and DLGAP1 knockdown suppresses cancer cell proliferation and induces apoptosis 5. Clinically, DLGAP1 polymorphisms may serve as biomarkers for OCD susceptibility, while DLGAP1 antisense RNAs represent potential therapeutic targets in cancer treatment.