In addition, it is presumed that the cause of anaphylaxis is a complement activation-related pseudoallergy (CARPA), in which the pre-existing IgG or IgM antibody to PEG activates complementarily, generating anaphylatoxins (C3a, C4a, and C5a), and causing mast cell degranulation [36]. This evidence concerns the gene C3 and anaphylaxis.