ADAMTS13 and thrombotic thrombocytopenic purpura: However, the common clinical presentation of TMAs, such as thrombotic thrombocytopenic purpura (TTP), in which ADAMTS13’s role is well understood [9,10], and PE/HELLP syndrome, suggests a linkage between the faulted expression of ADAMTS13 and the development of PE/HELLP syndrome [11].