In the last ten years, progress has been made concerning PNH in regards to both diagnosis and therapeutic approaches: high sensitivity flow cytometry enabled us to detect very small PNH clones [2], and the complement inhibitor eculizumab (ECU), a monoclonal antibody targeting C5, has significantly reduced hemolysis, anemia, and occurrence of thrombosis, reducing PNH-related morbidity and mortality [3]. The gene discussed is C5; the disease is anemia.