For example, VWD is considered the most common inherited bleeding disorder with an estimated prevalence up to 1%; it is due to deficiency and/or defects in the plasma protein VWF.29, 72, 73VWD is classified on the basis of quantitative deficiencies of VWF (VWD types 1 and 3) or qualitative defects in VWF (type 2 VWD), which may or may not be also associated with a quantitative deficiency of VWF. This evidence concerns the gene VWF and von Willebrand disease (hereditary or acquired).