GNS antibodies target glucosamine (N-acetyl)-6-sulfatase, a lysosomal enzyme critical in glycosaminoglycan (GAG) metabolism. This enzyme specifically cleaves sulfate groups from heparan sulfate and keratan sulfate, facilitating their degradation. Deficiencies in GNS due to genetic mutations cause mucopolysaccharidosis type IIID (MPS IIID), a rare lysosomal storage disorder characterized by GAG accumulation, leading to progressive neurological decline, skeletal abnormalities, and organ dysfunction. Research on GNS antibodies has been driven by the need to understand enzyme function, diagnose MPS IIID, and develop therapies. These antibodies are typically generated using recombinant GNS protein or peptide fragments, enabling the detection of enzyme expression and localization in tissues or cultured cells via techniques like Western blot, immunohistochemistry, or immunofluorescence. In diagnostics, GNS antibodies help identify enzyme deficiencies in patient samples, aiding confirmation of MPS IIID. Therapeutically, they support enzyme replacement therapy (ERT) development by monitoring recombinant GNS delivery and uptake in preclinical models. Recent studies also explore antibody-based chaperone therapy to stabilize mutant GNS enzymes, potentially restoring activity. Despite progress, challenges remain in optimizing antibody specificity and translating findings into clinical applications, underscoring the importance of continued research to improve outcomes for MPS IIID patients.