In the post-allo-HCT setting, complement inhibitors such as eculizumab, (anti-C5 monoclonal antibody), narsoplimab (IgG-4 monoclonal antibody that inhibits the effector enzyme MASP-2 of the lectin complement pathway), and coversin (C5 inhibitor) have already been used in the treatment of transplant-associated thrombotic microangiopathy (TA-TMA) (31–33). The gene discussed is C5; the disease is Genetic thrombotic microangiopathy.