SERPINI1 encodes neuroserpin, a serine protease inhibitor that inhibits plasminogen activators and plasmin 1. The protein functions in nervous system development and synaptic plasticity, with potential neuroprotective roles against tissue-type plasminogen activator damage [UniProt annotation]. SERPINI1 plays critical roles in neuronal axon extension and motoneuron development, as demonstrated by studies showing that loss of serpini1 function results in axon defects and anxiety-like behavior in zebrafish 2. Pathogenic SERPINI1 variants cause familial encephalopathy with neuroserpin inclusion bodies (FENIB), a rare neurodegenerative disorder characterized by progressive cognitive decline, myoclonus, and seizures 3. FENIB results from neuroserpin polymerization and intracellular aggregation 4. The disease typically presents in late childhood or early adulthood with median onset at 21 years and median death at 33 years, with 69% of patients showing poor response to antiseizure medications 3. Cerebral and cerebellar atrophy occur in approximately 69% of cases 3. Beyond neurological disease, SERPINI1 exhibits tumor-suppressive function in gastric cancer, where miR-21-mediated downregulation of SERPINI1 promotes cell cycle progression and tumor growth 5. Additionally, SERPINI1 levels are significantly reduced in aqueous humor of patients with primary open-angle glaucoma, suggesting potential involvement in ocular pathology 6.