The diagnosis is suspected on clinical (classical pentad of fever, microangiopathic hemolytic anemia, thrombocytopenia, renal dysfunction, and changes in mental status) and laboratory (anemia with schistocytes, increased reticulocytes (> 2.5%), thrombocytopenia, indirect (unconjugated) bilirubin > 2 mg/dL, undetectable haptoglobin, high lactate dehydrogenase) grounds and confirmed by very low levels (< 10%) of ADAMTS3 [59]. This evidence concerns the gene HP and Thrombocytopenia.