ASTN1 (astrotactin 1) is a neuronal-glial adhesion molecule essential for brain development. Its primary function is promoting neuronal migration along radial glial fibers during early brain development, particularly in the cerebellum, cerebral cortex, and hippocampus 1. ASTN1 facilitates the movement of postmitotic neuroblasts and granule cells, which is critical for normal cerebellar development and laminar brain organization 1. Mechanistically, ASTN1 operates through cell adhesion pathways and interacts with ASTN2 to implement radial-glia-guided neuronal migration 1. Beyond neurodevelopment, a circular RNA form (circ-Astn1) functions in non-neuronal tissues by regulating the miR-138-5p/SIRT1 axis, protecting endothelial cells from hyperglycemia-induced damage and promoting autophagy in spinal cord repair [PMID:40014196; 29]. In hepatocellular carcinoma, ASTN1 suppresses cancer cell migration and invasion via Wnt/β-catenin pathway inhibition 3. Bi-allelic ASTN1 variants cause diverse neurodevelopmental disorders ranging from mild to profound intellectual disability, often accompanied by autism spectrum disorder, ADHD, epilepsy, ataxia, and variable brain malformations including cerebellar dysgenesis, thin corpus callosum, polymicrogyria, and lissencephaly 1. ASTN1 variants also associate with alcohol dependence risk 4. Additionally, ASTN1 methylation status serves as a biomarker in gynecological cancer screening [PMID:35460075; 51].