LAUSR

Dear Editor, Type 3 von Willebrand disease (VWD) is the rarest (1 in 1 million) and the most severe VWD, characterized by undetectable, and low, plasma levels of von Willebrand factor (VWF) and factor (F) VIII (<20 IU/dL), respectively.1 Patients with type 3 VWD mostly present mucocutaneous bleeding, haematoma and haemarthrosis.2,3 Treatment is ondemand replacement of the missing factor. However, patients with a high risk of severe bleeding can receive prophylaxis.4 Inhibitor formation is a serious complication of replacement therapy in type 3 VWD. About 10% of the patients who develop inhibitor show severe anaphylactic reactions to any products containing VWF and they become nonresponsive. Inhibitor development is a multifactorial event that can be affected by causative mutation, type and duration of replacement therapy,