von Willebrand Disease

von Willebrand’s disease (vWD) is the most common inherited bleeding disorder with a prevalence as high as 1 to 2 percent in the general population. The main clinical manifestations include increased or easy bruising, recurrent epistaxis (nosebleeds), excessive bleeding during menstruation and/or childbirth, and postoperative bleeding (particularly after tonsillectomy or dental extractions). The disease is caused by an inherited defect in the von Willebrand factor (vWF), a large multimeric glycoprotein, with essential roles in primary homeostasis and as a carrier of coagulation factor VIII (FVIII) in the circulation¹. The symptoms of vWD are due a quantitative deficiency or qualitative dysfunction of vWF protein. A variety of point mutations, insertions, and deletions in the vWF gene and conversions with the pseudo gene have been described.^2,3

vWD is classified into three different subtypes⁴. Type 1 accounts for 70 percent of cases with deficiency of vWF, and is typically inherited as an autosomal dominant trait. About 60% of the variation in vWF plasma is due to genetic factors, although a definitive diagnosis is complicated by ABO blood type, ethnic background, reduced penetrance and variable expressivity. Type 2 accounts for 10 to 30 percent of cases and is characterized by qualitative abnormalities of vWF, which is further divided into four subtypes (2A, 2B, 2M, and 2N). Type 2A, 2B, 2M follow autosomal dominant inheritance, while type 2N and a rare type 2A variant follow autosomal recessive inheritance. Type 3 affects approximately 1 to 5 percent of cases and is characterized by very low or undetectable levels of plasma vWF. Type 3 is an autosomal recessive disease with either homozygous or compound heterozygous mutations. Affected individuals have severe bleeding that can be life-threatening if not recognized and treated.

To open a printable assay summary in a new window, click the link below.

von Willebrand Disease Assay Summary
(in portable document format (pdf) which requires Adobe® Acrobat® Reader™ to view or print; download latest version free)

Please submit the Test Request Form (TRF) and the von Willebrand’s Disease Patient Information Form when ordering this test.

References
1. Mannucci PM. N Engl J Med. 2004 Aug 12;351(7):683-94.
2. Keeney S, Cumming AM. Clin Lab Haematol. 2001 Aug;23(4):209-30.
3. Gupta PK et al. Br J Haematol. 2005 Sep;130(5):752-8.
4. Sadler JE. Thromb Haemost. 1994 Apr;71(4):520-5.

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