RGD uses the Human Disease Ontology (DO, https://disease-ontology.org/) for disease curation across species. RGD automatically downloads each new release of the ontology on a monthly basis. Some additional terms which are required for RGD's curation purposes but are not currently covered in the official version of DO have been added. As corresponding terms are added to DO, these custom terms are retired and the DO terms substituted in existing annotations and subsequently used for curation.
The loss of calcium salts from bones and teeth. Bacteria may be responsible for this occurrence in teeth. Old age may be a factor contributing to calcium loss, as is the presence of diseases such as rheumatoid arthritis.