VWF and thrombotic thrombocytopenic purpura: Congenital TTP (cTTP) is an ultra‐rare disorder defined by an inherited deficiency of the von Willebrand factor (VWF) cleaving enzyme a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) leading to the presence of highly adhesive ultra large VWF multimers.