More than 700 inherited metabolic diseases (IMDs) have been identified so far. Each single IMD is a rare condition, but collectively IMDs are affecting at least one in 500 newborns. Clinical presentation of IMDs is wide-ranging from involvement of single organ systems to multi-systemic disease, confronting patients with significant and often severe health problems resulting in high morbidity, reduced life expectancy, and low quality of life.
For a limited number of IMDs networking activities already exist on a European or international level. The E-IMD, E-HOD and iNTD family of IMD registries has a relevant impact on improving the health of patients with IMDs and facilitates post-authorisation safety studies (PASS) for orphan drugs. However existing registries still do exclude a significant portion of IMDs and do not fulfill all core recommendations made by the European Union Committee of Experts on Rare Diseases (EUCERD). The recent inception of the European Reference Network for Hereditary Metabolic Diseases (MetabERN) lays the foundation for the development of an overarching European IT platform for IMD registries.
The project consists of 3 components: (1) a novel registry platform for all known IMDs, (2) an upgrade of existing IMD registries and (3) a collaboration with the European Rare Kidney Disease Reference Network (ERKNet). The new Unified European Registry for Inherited Metabolic Diseases (U-IMD) will encompass all known IMDs, fully implementing EUCERD recommendations. Data modules developed for U-IMD will be integrated in the existing IMD registries, with the iNTD registry as pilot, thus reaching interoperability of patient records. MetabERN and ERKNet will develop a common standard for minimal core data sets.
The U-IMD registry will follow an open multiple stakeholder approach, explicitly seeking collaborations with national and EU level health authorities, other scientific networks and consortia, patient and parent organizations and industry.

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