VWF and thrombotic thrombocytopenic purpura: In 1982, Moake et al. recognized the abnormal composition of von Willebrand factor (VWF) multimers in the plasma of patients with TTP [2], and in 1998 Furlan et al. [3] and Tsai and Lian [4] identified ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) deficiency as the pathogenic cause of TTP.