Platelet-type von Willebrand disease (PT-VWD) is an autosomal dominant bleeding disorder caused by gain-of-function mutations of GP1BA gene coding for the platelet surface glycoprotein Ib alpha protein, the receptor for the adhesive protein von Willebrand factor (VWF). PT-VWD is unique among platelet disorders because of platelet hyperresponsiveness rather than decreased function. In PT-VWD patients, platelets bind the VWF and agglutinate spontaneously. This results in thrombocytopenia and reduction of plasma VWF as platelets are removed from circulation. Of note, there is a very similar disorder, type 2B von Willebrand disease (VWD) [DS:H02092], to be taken into consideration in differential diagnosis.
Pseudo-von Willebrand's disease. An intrinsic platelet defect with aggregation by unmodified human factor VIII/von Willebrand factor and enhanced adsorption of its high-molecular-weight multimers.
