Diagnosis in von Willebrand’s disease

Dear Ask The Doctor: My mother has been talking about her Von Willebrand's disease for quite some time now. She definitely has the symptoms to back it up, and the test results as well. But, I was researching the test results, and I'm not sure if I am misunderstanding them, or they are just plain wrong. The extensive test was by intranasal DDAVP. The first part of the test for Factor VIII acitivty showed an increase from 41% to 116%. Is this the percent compared to the levels of a person without? For the Von Willebrand antigen test, it showed an increase from 62% to 101%, and it says that a person with mild symptoms will have only 25% to 30%. This doesn't seem right. The last part of the test, for the multimers, says they are normal but they signify the disease. Does this make sense at all? Is it possible that my mom has a different type of the disease?

Dear Brad: Von Willebrand disease (VWD) is an inherited bleeding disorder. It is characterized by mutations that lead to an impairment in the synthesis or action of von Willebrand factor, a multimeric protein that is required for platelet adhesion. There are three types of von Willebrand’s disease. Type 1 is a mild quantitative defect (decreased amount of vWF). Type 2 is a qualitative defect (dysfunctional vWF). Type 3 is a severe total quantitative defect (no vWF produced). The VWF multimer assay is a visual assessment of the size and the banding pattern of VWF multimers on gel electrophoresis of the patient's plasma, and is used to identify variants of type 2 VWD that may indicate an abnormal VWF structure. If this assay is positive then your mother has von Willebrand’s disease, but I would advise discussing the individual test results with your mother’s haematologist.