BSN encodes Bassoon, a 420-kDa scaffold protein that organizes the presynaptic active zone, the site of neurotransmitter release 1. Bassoon participates in forming Piccolo-Bassoon transport vesicles that deliver synaptic proteins to developing synapses and regulates spatial organization of synaptic vesicles and membrane fusion machinery 1. Beyond structural functions, BSN regulates presynaptic protein ubiquitination, autophagy, and modulates neurotransmission by inhibiting presynaptic DAO enzyme activity. BSN variants cause a distinct neurodevelopmental disorder characterized by epilepsy (45% of cases), developmental delay (38%), and behavioral abnormalities including ADHD (25%) and autism (17%), with phenotypic severity varying across the age spectrum 2. Notably, protein-truncating BSN variants are associated with severe adult-onset obesity and type 2 diabetes, representing effects larger than established obesity genes, suggesting degenerative synaptic processes contribute to metabolic dysfunction 3. Recent mechanistic studies demonstrate that BSN mutations impair astrocyte lipid homeostasis and Kir4.1 potassium channel function, leading to reduced neurosupportive capacity and neuronal hyperexcitability 4. A mouse model carrying BSN mutations exhibits impaired working memory and dopaminergic neuronal loss in the substantia nigra 5. These findings establish BSN as critical for synaptic organization and reveal how presynaptic dysfunction extends to metabolic and glial-neuronal interactions.