P722: VariantMatcher and the variant-level matching network to facilitate variant classification and disease gene discovery

We aimed to evaluate the functional effects of two novel JAG1 missense variants, V176I and C271Y, identified in ALGS patients of the Severance hospital.Methods: To assess the pathogenicity of the variants, we performed immunofluorescence to evaluate protein localization, Endo H and Trypsin digestion assays for glycosylation status, and luciferase assays to measure Notch pathway activation.Results: Immunofluorescence revealed altered localization of both variants, with V176I showing partial mislocalization and C271Y exhibiting severe mislocalization.Glycosylation assays indicated incomplete processing for both variants, with a more pronounced defect in C271Y.Luciferase assays demonstrated partial Notch signaling activation for V176I, while C271Y showed complete loss of function.Conclusion: Our findings demonstrate distinct functional deficits associated with V176I and C271Y JAG1 variants.These results highlight the importance of functional studies in classifying JAG1 missense variants and contribute to improving ALGS diagnosis.