Despite the large number of clinical trials targeting C5, C5a, C5aR1 on AAV, IgAN, aHUS, PNH, and other diseases, and the approved clinical use of eculizumab for PNH, aHUS, and myasthenia gravis, clinical trials targeting C3 are less and mostly on phase I, and no clinical trials targeting C3a or C3aR are registered. This evidence concerns the gene C3AR1 and paroxysmal nocturnal hemoglobinuria.