The Orphanet Rare Disease ontology (ORDO) was initially jointly developed by Orphanet and the EBI to provide a structured vocabulary for rare diseases capturing relationships between diseases, genes and other relevant features which will form a useful resource for the computational analysis of rare diseases. It is derived from the Orphanet database www.orpha.net , a multilingual database dedicated to rare diseases populated from literature and validated by international experts. It integrates a nosology (classification of rare diseases), relationships (gene-disease relations, epidemiological data) and connections with other terminologies (MeSH, UMLS, MedDRA), databases (OMIM, UniProtKB, HGNC, ensembl, Reactome, IUPHAR, Genatlas) or classifications (ICD-10).

The ontology will be maintained by Orphanet and further populated with new data. Orphanet classifications can be browsed in the OLS view. The Orphanet Rare Disease Ontology is updated every six months and follows the OBO guidelines on deprecation of terms.

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These products have been recognised as an  Elixir Core Data Resource and a  Global Core Biodata Resource

These products are an  IRDiRC Recognized Resources

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