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 B cell deficiency that has_material_basis_in mutations in the IGLL1 gene. Lambda 5 mutations can cause a block in B cell development at the transition between the pro-B cell and the pre-B cell stage. (DO)