More than 1400 inherited metabolic diseases (IMDs) have so far been identified; the numbers are rapidly increasing, since new analytical high through-put methods help to unravel the molecular and metabolic basis of so far unknown diseases. Each IMD is a rare condition with estimated individual prevalence ranging from 0.1 to 15 in 100,000 newborns but taken together patients affected by IMDs are numerous with at least one in 500 newborns. Early diagnosis can improve outcomes. For many of these conditions, a significant delay in diagnosis still occurs. Additionally, knowledge about their natural history, the efficacy and safety of therapies, and long-term follow-up is incomplete.

Since IMDs are rare, experience of single expert centres is extremely limited and the evidence base of current diagnostic and therapeutic approaches is low. This causes significant inequalities and inequities for patients with IMDs and, consequently, has a significant impact on their health outcome as well as on the socio-economics of European countries.

For a limited number of IMDs networking activities already exist on a European or international level such as the EU-funded European Registry and Network for Intoxication type Metabolic Diseases (E-IMD; CHAFEA agreement no. 2010 12 01), the European Network and Registry for Homocystinurias and Methylation Defects (E-HOD; CHAFEA agreement no. 2012 12 02), and the International Working Group on Neurotransmitter Related Disorders (iNTD).

To date no overarching patient registry encompassing the majority of IMDs, independent from industry and built on the common data elements of the EU RD Platform exists. The “Unified European Registry for Inherited Metabolic Diseases (U-IMD)” being the first European registry that encompasses all 1400+ IMDs, aims at closing this gap. It will fully implement the EUCERD recommendations for rare disease registries and built on the common data elements of the EU RD Platform, thus applying the core features of the highly successful E-IMD, E-HOD and iNTD family of registries to the entire MetabERN disease panel and sharing methodological and operational expertise gained from previous EU-funded projects. MetabERN thus will be fitted out with a powerful and unique tool, compatible with the EU RD Platform that will be a crucial factor for the network to achieve its mission.