Bernard-Soulier syndrome (BSS) is a bleeding disorder caused by a defect in or deficiency of the platelet membrane von Willebrand factor receptor which is composed of 4 proteins, GP1BA, GP1BB, GP9 and GP5. The clinical feature is characterized by variable thrombocytopenia and large defective platelets.
Mutation of leucine-57 to phenylalanine in a platelet glycoprotein Ib alpha leucine tandem repeat occurring in patients with an autosomal dominant variant of Bernard-Soulier disease.