ADAMTS13 and thrombotic thrombocytopenic purpura: Evaluation of ADAMTS13 qualities, such as activity, conformation status, antibodies, and antigen, is highly significant in the TTP diagnosis, as open conformation of ADAMTS13 is a subtle marker of TTP confirmation, in cases where ADAMTS13 activity is borderline low (i.e., 10–20%), or when levels of anti-ADAMTS13 inhibitors remain insignificant [11,52] (Figure 1).