SNAP91 (synaptosome associated protein 91) functions as an adaptor protein in clathrin-mediated endocytosis, linking clathrin to membrane receptors during vesicle formation 1. The protein facilitates clathrin assembly and receptor concentration in coated vesicles, playing a crucial role in synaptic vesicle recycling and membrane trafficking processes. SNAP91 operates through binding interactions with clathrin, phosphatidylinositol lipids, and SNARE proteins to regulate vesicle budding from membranes. Disease relevance includes associations with multiple neuropsychiatric and oncological conditions. SNAP91 has been identified as a potential causal gene for schizophrenia through cross-ancestry genome-wide association studies 2 and implicated in neurodevelopmental disorders through deep intronic variants 3. In cancer contexts, SNAP91 shows decreased expression in glioblastoma and correlates with patient survival outcomes 4, while serving as a target of oncogenic microRNAs in esophageal cancer 5 and metastatic prostate cancer 6. Additionally, SNAP91 variants have been identified in high-risk Alzheimer's disease pedigrees 7. These findings suggest SNAP91 has clinical significance as both a diagnostic biomarker and potential therapeutic target across neurological and oncological diseases.