While von Willebrand disease (VWD) is the most common inherited blood disorder, with an estimated prevalence of approximately 1%, only 1 in 10 000 individuals have symptoms.7,8 Individuals with the disease have either decreased or abnormal von Willebrand factor (VWF), an essential primary hemostasis protein. This evidence concerns the gene VWF and von Willebrand disease (hereditary or acquired).