C3 and atypical hemolytic-uremic syndrome: Additionally, recent advances in monoclonal antibody therapies targeting complement factor C5, such as eculizumab and, more recently, C3, have revolutionized the management of diseases caused by the dysregulation of the complement system like paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS).