From OMIM
Von Willebrand disease is the most common inherited bleeding disorder. It is characterized clinically by mucocutaneous bleeding, such as epistaxis and menorrhagia, and prolonged bleeding after surgery or trauma. It results from a defect in platelet aggregation due to defects in the von Willebrand factor. Von Willebrand factor is a large, multimeric protein that plays a role in platelet adhesion and also serves as a carrier for the thrombotic protein factor VIII (F8; 300841). F8 is mutated in hemophilia A (306700) (review by Goodeve, 2010). Whereas von Willebrand disease types 1 (193400) and 3 (277480) are characterized by quantitative defects in the VWF gene, von Willebrand disease type 2, which is divided in subtypes 2A, 2B, 2M, and 2N, is characterized by qualitative abnormalities of the VWF protein. The mutant VWF protein in types 2A, 2B, and 2M are defective in their platelet-dependent function, whereas the mutant protein in type 2N is defective in its ability to bind F8. VWD2 accounts for 20 to 30% of cases of VWD (Mannucci, 2004; Sadler et al., 2006; Lillicrap, 2009; Goodeve, 2010). For a general discussion and a classification of the types of von Willebrand disease, see VWD type 1 (193400).  http://www.omim.org/entry/613554