[Atypical hemolytic uremic syndrome (aHUS): new insights into pathogenesis leading to novel therapeutic approaches].

The atypical hemolytic-uremic syndrome (aHUS) belongs to the thrombotic mictroangiopathies (TMA). This group of diseases has traditionally been divided on clinical grounds by affected organs into thrombotic-thrombocytopenic purpura (TTP) and hemolytic-uremic syndrome (HUS), the latter being termed atypical if not preceeded by diarrhea. Tremendous scientific advances of the last two decases have shown that these clinically overlaping syndromes are caused by distinct molecular mechanisms. The definition of clinical syndromes has therefore been replaced by a TMA-classification on a molecular-mechanistic basis. aHUS is caused by an uncontrolled activation of the alternative complement pathway mostly due to genetic defects. These insights and particularly the development of a specific terminal complement inhibitor have revolutionized the treatment of aHUS and considerably improved its prognosis.