Classically, these include thrombotic thrombocytopenic purpura (TTP) – a severe deficiency of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13, also known as von Willebrand factor-cleaving protease), and aHUS20. Here, ADAMTS13 is linked to thrombotic thrombocytopenic purpura.