Abdul Mannan: Type 2N VWD Can Wear Haemophilia A’s Lab Coat
Abdul Mannan, Consultant Haematologist, Director Haemophilia Centre, Haematology Lab Lead at Betsi Cadwaladr University Health Board, Founder of Blood Doctor, shared a post on LinkedIn:
“Type 2N von Willebrand disease can wear haemophilia A’s lab coat.
Low factor VIII. Similar bleeding. Different gene. Different family story.
Here is the trap:
- VWF normally binds and protects factor VIII.
- In type 2N, VWF is present, but its FVIII-binding function is defective. FVIII is cleared too quickly.
- VWF antigen and activity may be normal or reduced. FVIII is low out of proportion to VWF.
- The FVIII:C and VWF:Ag ratio is often below 0.6–0.7. But this is a clue, not a universal diagnostic cut-off.
- Confirm with a VWF:FVIIIB assay interpreted against VWF:Ag and the local laboratory range, and/or targeted VWF genetic testing.
- A VWF variant supports type 2N, which is usually autosomal recessive. An F8 variant points towards haemophilia A, which is X-linked.
Why does naming it matter?
Because treatment planning, family counselling and testing relatives all change. DDAVP response cannot be assumed either. In 123 genetically confirmed patients, Daniel and colleagues found genotype-linked variation in FVIII levels, bleeding and DDAVP response.
So when FVIII is low, ask one more question:
Is factor VIII missing, or has its carrier stopped holding on?
Would your laboratory pathway catch this before someone is labelled as having mild haemophilia A?”

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