The diagnosis of VWD type and subtype is crucial for many purposes: to make a differential diagnosis between VWD 2N and hemophilia A or between VWD 2B and a platelet disorder named “pseudo VWD or platelet type VWD,” [10] to predict the response to desmopressin [11] or the kinetic of VWF during pregnancy, to anticipate the risk of allo-immunization in patients with type 3 VWD [12] and to help for genetic counseling [13]. This evidence concerns the gene VWF and von Willebrand disease (hereditary or acquired).