Local (regional and national) rare disease registries vary with respect to data elements captured, representation and structure of the data, provenance, data quality, consent status and more. To allow data from multiple registries to be used as a single data source, these variations need to be overcome, or at least hidden from the user. FAIRVASC achieves this by deploying semantic web technologies (Resource Description Framework (RDF) uplift) to select, quality-assure and anonymise data from registries, annotate it using standards-compliant ontologies and terminologies (e.g. Orphanet Rare Disease ontology (ORDO), Human Phenotype Ontology (HPO) and make it available as a local RDF triple-store, via SPARQL (SPARQL Protocol and RDF Query Language) interfaces.