PROJECT SUMMARY In our current healthcare system, it often takes years before patients with rare conditions and rare presentations of common conditions receive a diagnosis. In 2013, the National Institutes of Health supported the creation of the Undiagnosed Diseases Network (UDN) to address the needs of these patients, to facilitate the diagnostic process for those with undiagnosed conditions and generate new knowledge about underlying mechanisms of disease. The UDN was successful in solving medical mysteries, shortening diagnostic odysseys, and contributing to biomedical research discovery. In order to serve more patients, the UDN process must be scaled and integrated into broader healthcare and research ecosystems. As the Data Management Coordinating Center (DMCC) for a network of Diagnostic Centers of Excellence, Harvard Medical School will leverage experience in the UDN to create sustainable, nationally scaled infrastructure to support diagnosis, research, and care for those who are undiagnosed. This will be accomplished by bringing together experts in trans-institutional data sharing, data analysis, clinical care, bioinformatics, novel diagnostics, and translational research and creating three DMCC Cores - Administrative, Data Management, and Clinical Research Support - to address unmet needs of the undiagnosed. The Administrative Core will unite the DMCC and support activities of all three Cores. Together, the DMCC Cores will accomplish four aims: 1) Scale up UDN throughput by at least an order of magnitude to meet a pressing national need, 2) Leverage partnerships for sustainable coordination of diagnostic processes to increase patient autonomy while advancing opportunities for investigative science, 3) Maximize data mobility, interpretability, and shareability, and 4) Provide analytic service and data stewardship through the Data Management Core and Clinical Research Support Cores led by experts in genomics and AI teaming with clinicians and researchers.