21 June 2023

Orphanet has developed and maintains the Orphanet nomenclature of rare diseases, that is cross-referenced with other international terminologies and reference databases (including OMIM, ICD-10, SNOMED-CT, MedDRA, UMLS, MeSH, and GARD) in order to enable interoperability between different information systems. The Orphanet classification is organised according to three hierarchical levels: Group of disorders, Disorder, and Subtype of a disorder, that determine the level of precision of each diagnosis included in the nomenclature. This classification level is indicated on the respective Orphanet website page of each clinical entity.

The European Commission has recommended the adoption of Orpha codes for designating rare diseases covered by the 24 European Reference Networks for Rare Diseases (ERNs). As knowledge evolves, there is need to create new entries and modify existing ones. Orphanet has established a procedure to support ERNs in this process: “Procedural document: Collaboration with networks of expertise for the revision of the Orphanet nomenclature and classification of rare diseases”.

The scheme that summarizes the process is depicted in the below figure, copied from the above cited document:


The websites https://od4rd.eu and https://www.orphadata.com/orphanet-nomenclature-for-coding/ may also bring further information and resources that may be helpful.
In order to facilitate the creation of the request and its adequate prioritization, EURO-NMD has started a dialogue with Orphanet and will assist his members in diverse forms during the procedure.
We also encourage our members to use the link that redirects to the form as it contains the required information to kick start the process. We will also be able to provide support to your request and monitor its progress in the different stages of the above workflow.

The ERNs are co-funded by the
European Union (Health Programme and CEF)

EU Commission

“EURO-NMD is one of the 24 European Reference Networks (ERNs) approved by the ERN Board of Member States. The ERNs are co-funded by the European Union (Health Programme and CEF).
For more information about the ERNs and the EU health strategy,
please visit ec.europa.eu/health/ern