Von Willebrand disease.

Von Willebrand disease (VWD) is the most common bleeding disorder. People with VWD have a problem with a protein in their blood called von Willebrand factor (VWF) that helps control bleeding. It is estimated that up to 1% of the world’s population suffers from VWD, but as many as 9 out of 10 people with VWD have not been diagnosed.