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The Orphanet Rare Disease Ontology (ORDO) is an open-access ontology developed from the Orphanet information system, enabling complex queries of rare diseases and their epidemiological data (age of onset, prevalence, mode of inheritance) and gene-disorder functional relationships.
biomedical, health, clinical, genomics, phenotype
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infores:ordo
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| ID | Name | URL | Category | Format | Description |
|---|---|---|---|---|---|
| ordo.owl | ORDO OWL | ORDO_en_4.7.owl (46.9 MB) | DataModelProduct | owl | ORDO in OWL format in English (v4.7) |
| ordo.sparql | ORDO SPARQL Endpoint | ordo-sparql-endpoint | ProgrammingInterface | ❔ | SPARQL endpoint for querying the ORDO... |
| ID | Name | URL | Category | Format | Description |
|---|---|---|---|---|---|
| orphacode.nomenclature | Orphanet Nomenclature Pack | pack-nomenclature | DataModelProduct | ❔ | The Orphanet nomenclature pack provid... |
| orphacode.api | ORPHAcodes API | api.orphacode.org | ProgrammingInterface | ❔ | API for accessing the Orphanet nomenc... |
| efo.owl | EFO OWL | efo.owl (229.5 MB) | OntologyProduct | owl | The latest release of EFO in OWL format |
| efo.obo | EFO OBO | efo.obo (61.1 MB) | OntologyProduct | obo | The latest release of EFO in OBO format |
| ubkg.neo4j | UBKG Neo4j Docker Distribution | ubkg-downloads.xconsortia.org | GraphProduct | ❔ | Turnkey neo4j distributions that depl... |
| ubkg.csv | UBKG Ontology CSV Files | ubkg-downloads.xconsortia.org | GraphProduct | csv | Ontology CSV files that can be import... |
The Orphanet Rare Disease Ontology (ORDO) is a comprehensive, structured vocabulary specifically designed for rare diseases. It integrates rare disease classification with relationships between diseases, genes, and other relevant features. ORDO has been developed and is maintained by Orphanet, a reference portal for information on rare diseases and orphan drugs.
ORDO is an open-access ontology derived from the Orphanet knowledge base, enabling complex queries of rare disorders and their associated data. It was initially jointly developed by Orphanet and the European Bioinformatics Institute (EBI) to provide a structured vocabulary for rare diseases that captures relationships between diseases, genes, and other relevant features.
The ontology consists of over 11,000 classes and 70,000+ annotation assertion axioms. Each concept from the Orphanet database forms a distinct OWL (Web Ontology Language) class and is associated with other classes using defined object properties.
ORDO represents:
An Evidence Code Ontology (ECO) is used to encode the provenance of assertions made in ORDO.
Central to ORDO is the Orphanet nomenclature, a multilingual, standardized, controlled medical terminology specific to rare diseases. Each clinical entity (disorder, group of disorders, or subtype) is associated with a unique numerical identifier called an ORPHAcode, along with a preferred term, synonyms, and a definition.
The Orphanet nomenclature is organized in a classification system structured around major medical specialties according to diagnostic and therapeutic relevance. This clinical coding system is mapped to main generic clinical and genetic terminologies, providing a common language across healthcare and research systems.
ORDO is widely used for:
The ontology is particularly valuable for projects needing to integrate rare disease data with other biological and clinical information, as it provides a standardized framework for rare disease classification and annotation.
ORDO is available under the Creative Commons Attribution 4.0 International (CC BY 4.0) license. It is bi-annually released in July and December and can be accessed in multiple formats including OWL and OBO.
ORDO has been recognized as an ELIXIR Core Data Resource, a Global Core Biodata Resource, and an IRDiRC Recognized Resource, attesting to its quality and importance in the rare disease research community.
Created: June 04, 2025 | Last modified: December 13, 2025