This study was performed in part to assess the utility of VWF activity/Ag ratios to capture type 2 VWD cases, particularly relevant in the age of the latest diagnostic VWD guidelines [2], which recommend use of newer VWF:GPIbB assays (VWF:GPIbM or VWF:GPIbR) ahead of classical VWF:RCo since they would likely yield lower variability, better low VWF level sensitivity, and improve VWD diagnosis reliability. This evidence concerns the gene VWF and von Willebrand disease (hereditary or acquired).