[1][2][3] The Disease Ontology project is hosted at the Institute for Genome Sciences at the University of Maryland School of Medicine.
The Disease Ontology project was initially developed in 2003 at Northwestern University to address the need for a purpose-built ontology that covers the full spectrum of disease concepts annotated within biomedical repositories within an ontological framework that is extensible to meet community needs.
Disease Ontology Identifiers (DOIDs) consist of the prefix DOID: followed by number, for example, Alzheimer's disease has the stable identifier DOID:10652.
DO is cross-referenced in several resources such as UniProt.
The Disease Ontology entry for motor neuron disease in OBO format is given below, showing the links to other classification schemes, including ICD-9, ICD-10, MeSH, SNOMED and UMLS.