PNA binding correlates with propeptide/VWF ratios. (A) VWF propeptide and mature VWF antigen levels were determined for healthy volunteers (n = 24) and VWD type 1 patients (n = 32) depicted in Figure .4, and the molar ratio propeptide over VWF was calculated as described.²⁶  Difference between both groups was tested using the unpaired 2-tailed t test with the Welch correction applied. (B) Values for relative PNA binding obtained for VWD type 1 patients were plotted versus the corresponding propeptide/VWF ratios. The drawn line was obtained after linear regression analysis. Correlation was found to be significant (Spearman rank = 0.50; P = .004). Bars represent mean values.