VWF multimeric analysis of pretreatment samples for TTP and aHUS patients. In each run shown, a normal control plasma (NC) and an abnormal control plasma (AC, obtained from a patient with type 2 von Willebrand disease) were included to verify the performance and resolution of the analysis. The area above the solid line in the figure represents the larger multimers with molecular weight higher than band #15 (indicated by an arrow) counted from the bottom of the gel. This area, indicated by an vertical line in the figure, is referred to as ULVWF. (A) Multimeric analysis from 19 acquired TTP patients. (B) Multimeric analysis from 19 aHUS patients. A sample from a TTP patient containing ULVWF is included in panel B for comparison. In a few aHUS patients, faint bands above the dotted line can be seen that represent normal variation rather than pathologically increased ULVWF multimers.