The most common acquired drivers in primary IC-MPGN and C3G are the C3 nephritic factors (C3NeFs) (17–20) a heterogeneous group of autoantibodies that bind to neoepitopes of the C3 convertase complex C3bBb, the key amplifying enzyme of the complement alternative pathway that cleaves C3 to C3a and C3b (21, 22). The gene discussed is C3; the disease is complement 3 glomerulopathy.