von Willebrand Disease, Type 2B

**Semantic type:** Disease or Syndrome

**Definition:** An autosomally inherited (generally dominant) coagulation disorder characterized by qualitative abnormalities of the von Willebrand factor (VWF). The mutant VWF shows increased affinity to platelet glycoprotein Ib alpha, resulting in increased platelet aggregation, and increased proteolysis of VWF subunits causing a decrease of large VWF multimers; patients often have secondary thrombocytopenia due to platelet consumption.