GALNT17 encodes a polypeptide N-acetylgalactosaminyltransferase localized to the Golgi apparatus that catalyzes the initial step of O-linked oligosaccharide biosynthesis by transferring N-acetyl-D-galactosamine residues to serine or threonine residues on protein receptors. While the enzyme's canonical biochemical function involves glycan synthesis, GALNT17 has emerged as a brain-expressed gene with important roles in neurodevelopment. In mice, dysregulation of Galnt17 contributes to cerebellar and hippocampal pathologies associated with abnormalities in growth, learning, memory, and behavior, with transcriptomic evidence implicating disrupted neuron and synapse maturation, neurotransmitter signaling, and cellular stress pathways 1. GALNT17 variants are implicated in neurodevelopmental and neurodegenerative disorders: a Parkinson's disease-associated GWAS variant (rs9638616) in GALNT17 is associated with altered white matter microstructure and supplementary motor area functional connectivity, mediating effects on motor severity 2. The GALNT17 locus also contributes to social behavior regulation within the Williams-Beuren syndrome control region, with implications for autism spectrum disorder susceptibility 3. Additionally, GALNT17 genetic variants are associated with age-related cataract risk through galactose metabolism pathways 4. These findings indicate GALNT17 functions extend beyond glycosylation to encompass critical roles in CNS development and function.