Von Willebrand disease type 2N: An update

Area of Science:

• Hematology
• Genetics
• Molecular Biology

Background:

• Von Willebrand factor (VWF) defects cause von Willebrand disease (VWD), the most common inherited bleeding disorder.
• Type 2N VWD is a rare, recessive form caused by mutations affecting VWF's binding site for factor VIII (FVIII).

Purpose of the Study:

• To review the pathophysiology, diagnosis, treatment, and molecular biology of type 2N VWD.
• To highlight the importance of differentiating type 2N VWD from hemophilia A and its carrier state.

Main Methods:

• Review of existing literature on type 2N VWD.
• Discussion of diagnostic laboratory assays, including VWF binding capacity for FVIII (VWF:FVIIIB) and genetic analysis.

Main Results:

• Type 2N VWD presents with low FVIII coagulant activity (FVIII:C) and disproportionately high VWF antigen, often with autosomal recessive inheritance.
• Impaired VWF-FVIII binding leads to rapid FVIII clearance, despite preserved VWF interactions with platelets and collagen.

Conclusions:

• Accurate diagnosis of type 2N VWD is essential for appropriate genetic counseling and effective treatment strategies.
• Distinguishing type 2N VWD from hemophilia A is critical and achievable through specific laboratory testing of VWF-FVIII binding interactions.