Rare Diseases and classifications

Orphanet maintains the Orphanet nomenclature of rare diseases, essential in improving the visibility of rare diseases in health and research information systems: each disease in Orphanet is attributed a unique and stable identifier, the ORPHA code. The nomenclature is organised in a poly-hierarchial classification, and data set includes: types of disorders, flags of disorders, new relations between disorders, and characterisation of the alignments between disorders and external terminologies or resources (OMIM, ICD-10, MeSH, UMLS, MedDRA and GARD). The alignments are characterised in order to indicate if the terms are perfectly equivalent (exact mapping) or not.
For analysis purposes, each disorder is attributed to a preferred classification by linking it to the head of classification entity (Linearisation of disorders). As some decisions could be made somewhat arbitrarily, we have written a set of rules to make sure attributions are consistent (see below procedure on Linearisation rules for Orphanet classifications).
Hence, users are allowed to access to 4 differents data sets: Orphanet nomenclature files for coding, Rare diseases and cross referencing, Classifications of rare diseases and Linearization of disorders.

Orphanet nomenclature files for coding

Cross-referencing of rare diseases

Classifications of rare diseases

Linearisation of disorders

Video tutorials

What is the Orphanet nomenclature of rare disorders?

Frequently Asked Questions

Free access products description

Orphanet procedures

Orphanet nomenclature and classification of rare diseases

ICD-10 coding rules for rare diseases

Naming rules for the rare disease nomenclature in English

Nomenclature production in national language

Linearisation rules for Orphanet classifications

Orphanet Standard Operating Procedures