AP1G1 encodes the gamma-1 subunit of adaptor protein complex 1 (AP-1), a heterotetrameric clathrin-associated complex essential for intracellular vesicular trafficking and protein sorting at the trans-Golgi network and endosomes 1. The AP1γ1 subunit is critical for clathrin-coated vesicle formation and recognition of sorting signals in transmembrane cargo molecules 1. Functionally, AP1G1 mediates endosome recycling pathways and regulates polarized localization of somatodendritic proteins in neurons 1. The protein forms molecular complexes with other membrane receptors, such as ASCT2-EGFR, facilitating receptor-mediated endocytosis 2. AP1G1 also serves as a host dependency factor for coronavirus replication, likely regulating TMPRSS2 activity at the plasma membrane 3. Pathogenic variants in AP1G1 cause Usmani-Riazuddin syndrome, a neurodevelopmental disorder characterized by intellectual disability, developmental delay, and epilepsy 14. Both de novo heterozygous and bi-allelic variants have been identified as disease-causing 1. Animal studies demonstrate that complete AP1G1 loss is embryonic lethal, while hypomorphic mutations cause abnormalities in polarized epithelial cells of sensory organs 56. The gene's critical role in development and neuronal function makes it clinically significant for understanding adaptinopathies and neurodevelopmental disorders.