An update on type 2B von Willebrand disease

Area of Science:

• Hematology
• Molecular Biology
• Genetics

Background:

• Type 2B von Willebrand disease (VWD) is a rare bleeding disorder, representing less than 5% of all VWD cases.
• Mutations in the A1 domain of von Willebrand factor (VWF) lead to enhanced binding with platelet glycoprotein Ibα (GPIbα).
• This abnormal interaction results in increased platelet clearance and loss of high-molecular-weight VWF multimers, crucial for hemostasis.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying Type 2B VWD.
• To discuss the diagnostic challenges posed by clinical heterogeneity.
• To review current and optimal therapeutic strategies for managing bleeding events.

Main Methods:

• Analysis of VWF-platelet interactions.
• Review of clinical case variations and mutation correlations.
• Evaluation of treatment outcomes for platelet transfusion, desmopressin, and VWF replacement therapy.

Main Results:

• Mutations in the VWF A1 domain enhance VWF binding affinity to platelet GPIbα.
• Clinical presentations vary significantly, complicating diagnosis even with identical mutations.
• Platelet transfusions can be ineffective due to aggregation, and desmopressin may increase bleeding risk.

Conclusions:

• Type 2B VWD is characterized by a specific gain-of-function mutation affecting VWF-platelet interaction.
• Effective management requires careful consideration of diagnostic variability and treatment limitations.
• Replacement therapy with factor VIII/VWF concentrates is the preferred and most effective treatment for bleeding in Type 2B VWD.