SYT12 (synaptotagmin 12) is a synaptic vesicle phosphoprotein with dual roles in neural and cancer biology. In normal neurotransmission, SYT12 enhances spontaneous neurotransmitter release and is essential for mossy-fiber long-term potentiation in the hippocampus, though unlike other synaptotagmins, it does not bind calcium or phospholipids 1. SYT12 associates with presynaptic SNARE machinery and its abundance correlates with better cognitive performance and brain reserve in aging 1. Importantly, SYT12 expression is downregulated during hypothyroid brain development, suggesting thyroid hormone regulation of synaptic development 2. Pathologically, SYT12 functions as an oncogene across multiple cancer types. In lung adenocarcinoma, elevated SYT12 promotes cell proliferation and migration via PI3K/AKT/mTOR pathway activation 3. In gastric cancer, SYT12 overexpression induces epithelial-mesenchymal transition and predicts poor prognosis 4. In papillary thyroid cancer, SYT12 is upregulated and serves as a prognostic biomarker for metastasis prediction 5. SYT12 stability in thyroid cancer is regulated by SPOP-mediated proteasomal degradation, dependent on GSK-3β-mediated phosphorylation of its degron motif 6. In pancreatic cancer, SYT12 is part of an immune-related signature predicting immunotherapy response 7. These findings establish SYT12 as a potential therapeutic target in cancer precision medicine.