Developing a standard dataset in the European registries for rare endocrine and bone conditions-a Melorheostosis...

Melorheostosis is a rare skeletal and connective tissue disorder with the estimated prevalence of 1/1,100,000. Low prevalence of rare diseases (RDs) can lead to suboptimal knowledge and expertise among clinicians.

The European Registries for Rare Endocrine and Bone Conditions (EuRREB) facilitates collection of a set of Core Data Elements and a specific dataset within the 'condition specific module' of the Core Registry platform. The Rare Bone Disease Action Group of the European Calcified Tissue Society (ECTS) collaborated with ERN BOND to develop a specific dataset for Melorheostosis.

An initial dataset was shortened to 44 unique variables. In January 2023, the Melorheostosis condition specific module was published and now consists of 18 patients from 2 countries. The median age of patients was 49 years old (range 23-82) and female to male ratio was 15:3 (83.3%). Family history of Melorheostosis was negative for all patients. The most affected bones were lower limbs in 12 cases (66.7%). Specifically, spine, feet and ribs were involved each in 2 cases (11%), skull and pelvis-in one patient each (5.5%). Two patients (11%) suffered from more than 1 lesion. Hyperostosis was present in 3 patients (16.7%), skeletal deformity-in 6 (33%), joint stiffness - in 11 (61%), asymmetry-in 16 (88.9%), joint limitation-in 12 (66.7%) patients. Swelling and muscle atrophy were reported in 1 case each (5.5%), vascular abnormalities-in 2 cases (11%), skin abnormality in 1 case (5.5%). Pain was present in 14 from 18 patients (77.8%). Genetic testing was performed in 5 patients (27.7%).

A condition specific module, for Melorheostosis, within an established registry has been developed. This will serve a useful resource to inform clinicians about this rare disease, and can support several healthcare initiatives such as guidelines creation and healthcare improvement strategies.