Recent functional and structural data using FHR-1 and disease-associated FHR-1 mutants have advanced our knowledge of the physiological role of FHR-1 and helped us to delineate a novel mechanistic framework for the association of FHR-1 with various diseases like aHUS, C3G, IgA-nephropathy (IgAN) and age-related macular degeneration (AMD) (12–14). The gene discussed is CFHR1; the disease is IgA glomerulonephritis.