VWF and thrombotic thrombocytopenic purpura: The pathogenesis may be autoimmune in nature since autoantibodies against ADAMTS13 (acronym for a Disintegrin and a Metalloproteinase with Thrombospondin-1 Motifs, 13th member of the family), which cleaves von Willebrand Factor (vWF), are typically present in most cases of idiopathic TTP.