Autoimmune thrombotic thrombocytopenic purpura (iTTP) is a potentially life-threatening, relapsing disease in which an acquired deficiency of the von Willebrand factor (VWF)-cleaving protease, ADAMTS13, leads to generalised microvascular thrombosis in various organs [1]. This evidence concerns the gene ADAMTS13 and acquired thrombotic thrombocytopenic purpura.