As reported, high‐dose IVIg targeted on C3 is used in dermatomyositis patients,96 eculizumab (a C5 blocker) is used in paroxysmal nocturnal hemoglobinuria, atypical haemolytic uremic syndrome, neuromyelitis optica and myasthenia gravis97 and avacopan (a specific C5aR1 antagonist) is used in antineutrophil cytoplasmic antibody‐associated vasculitis.98 This evidence concerns the gene C5 and neuromyelitis optica.