Patient #1, with the functionally inactivating Factor H/FHL-1 antibody, and patients #2 and #3, both expressing functionally defective Factor H and FHL-1, showed low C3 levels, AP dysregulation, and highly associated renal pathology in the form of C3G (at the time diagnosed as MPGN II/DDD). The gene discussed is FHL1; the disease is primary membranoproliferative glomerulonephritis.