The measurement of ADAMTS13 antigen levels and enzyme activity is important for TTP diagnosis, and to distinguish the clinical symptoms of this disease from other thrombotic microangiopathies like Hemolytic-Uremic Syndrome (HUS), disseminated intravascular coagulation (DIC) and the HELLP syndrome [4,24]. This evidence concerns the gene ADAMTS13 and Genetic thrombotic microangiopathy.