NFASC (neurofascin) encodes a cell adhesion protein that plays critical roles in nervous system development and function. The protein is essential for proper formation and maintenance of nodes of Ranvier and paranodal junctions in both central and peripheral nervous systems 1. NFASC exists in multiple isoforms, including neurofascin-155 (NF155) localized to paranodal regions and neurofascin-140/186 (NF140/186) found at nodes, where they interact with contactin-1 and contactin-associated protein 1 to maintain axo-glial integrity 2. Disease relevance includes autoimmune neuropathies where anti-neurofascin antibodies cause chr1 inflammatory demyelinating polyradiculoneuropathy (CIDP) and related conditions 13. Anti-pan-neurofascin antibodies induce severe, acute neuropathy with high morbidity through complement-mediated damage to nodes and paranodes 3. Genetic variants in NFASC have been identified as risk factors for progressive supranuclear palsy, suggesting broader neurological relevance 4. The protein is also implicated in intellectual disability and appears elevated in long COVID patients with cognitive impairment, indicating roles in nerve tissue repair 56. Clinical significance lies in antibody testing for accurate diagnosis of autoimmune neuropathies and guiding immunosuppressive treatment strategies.