Abstract
BACKGROUND: Although individual rare and complex diseases (RDs) affect small patient populations, together they impact an estimated 27–36 million people across the European Union. Addressing this major public health challenge has been a long-term priority for the European Union, leading to the establishment of the European Reference Networks (ERNs) in 2017. MAIN BODY: ERNs are cross-border networks connecting clinical expert centres to share knowledge, improve and harmonise diagnosis and care for patients with rare and complex diseases. Since their inception, 24 ERNs have united 1,606 expert centres across 375 hospitals in all EU Member States and Norway. Their activities span multidisciplinary clinical collaboration, patient-centred governance, education and training, and the development of clinical guidelines. Over 4900 extremely rare or difficult cases have been discussed among experts without requiring the patients to travel abroad when expertise was not available in their own countries. A key factor for this success is the cross-border IT platform - known as the Clinical Patient Management System 2.0 - provided by the European Commission for medical discussions, which enables experts to share patient data, including medical images and lab results, in a secure and protected environment that is fully compliant with all relevant security and data privacy requirements. ERNs have demonstrated resilience in crises such as the COVID-19 pandemic and the war in Ukraine, providing rapid, coordinated responses to sustain care for vulnerable patient groups. The first formal evaluation in 2023 confirmed that more than 95% of member centres met quality standards, underscoring the networks’ maturity and effectiveness. Moving into the next phase, the Joint Action JARDIN (2024–2027) aims to integrate ERNs into national healthcare systems to ensure sustainability and equitable access to high-quality RD care. CONCLUSIONS: ERNs exemplify European solidarity and innovation in healthcare, transforming how rare disease expertise is shared and applied across borders. Their continued integration into national systems will be pivotal to achieving a truly cohesive European Health Union that delivers improved outcomes for all patients with rare and complex diseases.