Bernard–Soulier syndrome (BSS) is a rare autosomal recessive bleeding disorder that is caused by a deficiency of the glycoprotein Ib-IX-V complex (GPIb-IX-V), the receptor for von Willebrand factor.

[6] Bernard–Soulier syndrome often presents as a bleeding disorder with symptoms of:[7] In regards to mechanism, there are three genes, GP1BA, GP1BB and GP9 that are involved (due to mutations).

[5][8] The differential diagnosis for Bernard–Soulier syndrome includes both Glanzmann thrombasthenia and pediatric Von Willebrand disease.

[5] BSS platelets do not aggregate to ristocetin, and this defect is not corrected by the addition of normal plasma, distinguishing it from von Willebrand disease.

BSS presents as a bleeding disorder due to the inability of platelets to bind and aggregate at sites of vascular endothelial injury.