In patients with paroxysmal nocturnal hemoglobinuria (PNH), a hemolytic anemia caused by an acquired deficiency of the terminal complement regulators CD55 and CD59, therapy with eculizumab was associated with a significant reduction of intravascular hemolysis, thrombotic events, and transfusion requirements, as well as the improvement of anemia, dyspnea, fatigue, and quality of life [195,196]. The gene discussed is CD55; the disease is paroxysmal nocturnal hemoglobinuria.