BOF: Clotting (Haemophilia)

Western-blot / chemiluminescent-based multimer analysis of von Willebrand protein forms part of the diagnostic array used to subclassify von Willebrand disease (VWD). What pattern would be seen in type type 2N VWD?

a) Absent high molecular weight multimers with normal low molecular weight multimers

b) Globally reduced multimers with normal distribution of high and low molecular weight multimers

c) Globally absent multimers

d) Markedly increased high molecular weight multimers

e) Normal multimer pattern

The Answer is:

Normal multimer pattern

Explanation:

Type 2N VWD is characterised by normal multimer analysis but abnormal APTT. The dysfunction arises from the absence of a factor VIII binding site.

Reference:

Laffan M, Brown SA, Collins PW et al. The diagnosis of von Willebrand disease: a guideline from the UK Haemophilia Centre Doctors' Organization. Haemophilia 2004 May;10(3):199-217.