VWF and von Willebrand disease (hereditary or acquired): VWD is recognized as a hereditary hemostatic disorder stemming from the aberration of the gene residing on chromosome 12 that is essential for the synthesis of von Willebrand factor (VWF), a large multimeric glycoprotein constantly produced by endothelial cells and megakaryocytes (Ruggeri and Ware, 1993; Ruggeri, 2003).