von Willebrand disease is the most common inherited bleeding disorder in humans. VWD can be classified into three major types, designated Types 1, 2 and 3; Type 2 can be further separated into subtypes 2A, 2B, 2M and 2N. The diagnosis of VWD requires a personal and family history of bleeding and confirmation by laboratory analysis. Although Types 2 and 3 are relatively straightforward to diagnose, there may be a risk of overdiagnosis of Type 1 because of an overlap within the normal range. We also report on the clinical profile and diagnosis of VWD in a South American cohort of patients and on the in vitro characteristics of some factor concentrates available for treatment of VWD.

A b s t r a c tWe developed a new method for the detection of large von Willebrand factor (vWf) Von Willebrand Factor (vWf) is a glycoprotein that is synthesized by megakaryocytes and endothelial cells. It is found in plasma, subendothelial matrix, and platelets. The smallest form, a 500-kd dimer, is polymerized to more than 20 multimers of different sizes; the largest can reach a molecular weight of more than 15,000 kd.