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.
A localized arrested tooth development which appears to involve most commonly the anterior teeth, usually on one side of the midline, most often the maxillary central and lateral incisors. Roentgenographically, the teeth have a ghostlike appearance. Calcification and bits of prismatic enamel may be found in the pulp and the enamel is thin and absent in part. (Jablonski, Illustrated Dictionary of Dentistry, 1982)