From data to drug: the translational impact of RaDaR, the UK national registry of rare kidney diseases

Each rare kidney disease affects relatively few individuals, but collectively these disorders place a significant burden on patients, families, healthcare systems, and society. Historically, therapeutic development has been limited by diagnostic challenges, small and underpowered trials, and a lack of disease-specific, clinically meaningful endpoints acceptable to regulators. The UK National Registry of Rare Kidney Diseases (RaDaR) was launched in 2010 to address these challenges by capturing high-quality longitudinal data. With over 37,000 participants enrolled across more than 100 UK sites, RaDaR now functions as a nationally integrated research platform supporting epidemiological studies, biomarker and genomic research, clinical trial feasibility and recruitment, patient-reported experience studies, and health economic evaluations. RaDaR's infrastructure and stakeholder engagement have advanced understanding of disease natural history and surrogate endpoints and have informed trial design. Analyses from RaDaR have helped quantify progression risk in IgA nephropathy and other glomerulopathies, supporting proteinuria reduction as a surrogate endpoint for regulatory approval. RaDaR data have informed NICE appraisals and supported clinical trials targeting specific molecular subgroups. By integrating clinical, laboratory, and hospital episode data, and by maintaining sustained patient engagement, RaDaR enables research that is both scalable and patient-centred. Its role in trials for focal segmental glomerulosclerosis, Alport syndrome, and C3 glomerulopathy exemplifies its contribution to precision nephrology. For the rarest conditions, international collaboration remains essential to achieve adequately powered datasets and harmonised endpoints. RaDaR demonstrates how a national registry can bridge the gap between real-world data and therapeutic development, accelerating the path from disease understanding to drug approval in rare kidney disease.