COG8 is a subunit of the conserved oligomeric Golgi (COG) complex, an eight-protein cytosolic tethering complex essential for retrograde vesicular trafficking and Golgi organization 1. COG8 is required for normal Golgi function and plays a critical role in intra-Golgi vesicle-mediated transport and retrograde transport from the endosome to the trans-Golgi network 2. Mechanistically, COG8 integrity is necessary for assembly of both the COG complex itself and Golgi SNARE complexes, which mediate vesicle tethering and fusion 3. COG8 deficiency disrupts glycosyltransferase localization and sialylation, leading to congenital disorder of glycosylation type IIh (CDG-IIh), characterized by severe psychomotor retardation, seizures, and failure to thrive 4. Additionally, alcohol-related DNA methylation at COG8 regulatory regions shows causal association with psychiatric disorders through altered COG8 brain expression 5. Recent evidence indicates COG8 is critical for influenza virus infection, as COG8 knockout enhances cellular antiviral resistance by blocking early endosome trafficking and enhancing immune responses 2. A TMED6-COG8 fusion protein serves as a molecular marker for TFE3 translocation renal cell carcinoma 6. Understanding COG8 function is clinically relevant for developing therapeutic strategies targeting both glycosylation disorders and viral infections.