VWF and thrombotic thrombocytopenic purpura: Classic TTP results from the deficiency or malfunction of a desintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13), which fails to cleave the ultralarge multimers of the von-Willebrand factor (v-WF) that are released by endothelial cells [10].