CNTN1 (contactin 1) is a cell adhesion molecule that mediates cell-cell interactions critical for nervous system development. It functions primarily in forming paranodal axo-glial junctions in myelinated peripheral nerves and facilitates signaling between axons and myelinating glial cells through association with CNTNAP1. CNTN1 acts as a NOTCH1 ligand, promoting oligodendrocyte generation via NOTCH1 activation and nuclear translocation of the notch intracellular domain. The protein also participates in axon guidance; interaction with TNR induces neuronal repulsion and inhibits neurite outgrowth. At the molecular level, CNTN1 genetic variation impacts white matter microstructure by modulating axon density in the corpus callosum 1. Clinically, CNTN1 is associated with congenital myopathy 12 and autoimmune nodopathy. Anti-CNTN1 antibodies are identified in approximately 6 of 401 CIDP patients studied, distinguishing autoimmune nodopathy from chr12 inflammatory demyelinating polyradiculoneuropathy, with affected patients showing ataxia, cranial nerve involvement, and poor response to intravenous immunoglobulin 2. Additionally, CNTN1 serves as a target antigen in membranous nephropathy, an autoimmune kidney disease causing nephrotic syndrome, identified in both single and dual-antigen presentations 345. CNTN1 is also recognized as a neural-associated biomarker with prognostic significance in hepatocellular carcinoma 6.