ADAMTS13 and atypical hemolytic-uremic syndrome: The principal subtypes of TMA are thrombotic thrombocytopenic purpura (TTP) mainly due to anti-ADAMTS13 autoantibodies and the hemolytic uremic syndrome (HUS) associated with shigatoxin-related endothelial toxicity (shiga-toxin related HUS) or with complement alternative pathway dysregulation (atypical HUS or aHUS).