Von Willebrand Disease is caused by low levels of functional von Willebrand factor. Von Willebrand factor has two main functions: 1) connecting platelets to sites of injured blood vessels and 2) protecting factor VIII from normal breakdown in the blood circulation. There are at least 6 types of von Willebrand Disease. Testing can be complex and requires tests of protein levels as well as the function of von Willebrand factor and often examination of the von Willebrand factor gene. Treatment is with infusion of von Willebrand factor into the vein or by releasing stored von Willebrand factor using desmopressin.

Other factor deficiencies are more rare but can include factor V, factor VII, factor X, factor XI, and fibrinogen. These disorders are also are diagnosed by measuring the factor levels and often evaluation of the corresponding gene.