The European Registry for Rare Bone and Mineral Conditions (EuRR-Bone) is closely linked to the European Reference Networks on Rare Bone Diseases (ERN BOND) and Rare Endocrine Conditions (Endo-ERN) and with its registry EuRRECa. It is however open to all professionals involved in the care of bone and mineral conditions. In EuRR-Bone we offer an electronic reporting tool (e-reporting of rare conditions, e-REC) for capturing newly encountered cases without collecting personal data.

To describe the generated data on Bone and Mineral conditions via e-REC in the first 18 months of its existence, from April 2020 to September 2021.

e-REC users receive invitations to complete a monthly online return which collects the number of new paediatric (<18) and adult (≥18) cases of conditions that are included in the registry. Diseases are mapped according to ORPHANET codes.

42 centres from 18 countries are active reporters, of which 14 are ERN BOND members, 26 are Endo-ERN members and 14 have no ERN affiliation. A total of 253 adult and 383 paediatric new cases of Bone or Mineral conditions were registered. Amongst adults, the most frequently reported conditions were hypoparathyroidism (21%), fibrous dysplasia (18%) and hyperparathyroidism (20%), while in children osteogenesis imperfecta (17%), achondroplasia (14%) and X-linked hypophosphataemia (11%) were the most reported. An increase in the number of reporting centres from 12 to 42, and in the number of cases from 23 to 636 cases, was documented in e-REC during the registry second year of activity.

e-REC is an easy-to-use online tool that objectively maps the occurrence of rare bone and mineral conditions among centres and countries. The growing e-REC user community and number of reported cases have facilitated the development of related projects such as secondary surveys that aim to collect a brief amount of data for understanding certain aspects of the reported condition.