von Willebrand Factor Multimers

The von Willebrand Factor (vWF) protein is a large molecule with a multimeric structure containing subunits with molecular weights up to, and exceeding, 2 million daltons. The ability to form such multimers is necessary for the normal function of the vWF molecule.

Defective multimer formation results in a qualitative abnormaility of vWF and multimer analysis can therefore be helpful in classifying the subtype of von Willebrand's Disease.

The vWF Multimer assay is performed by subjecting the patient's plasma to electrophoresis in an agarose gel and then detecting the vWF subunits with a specific antibody to vWF. A normal multimeric pattern contains a full range of multimers (low and high molecular weight).

Type 1 vWD has low levels of vWF activity and antigen, but the multimeric structure is normal.

Type 2 vWD exhibits a lack of intermediate or high molecular weight multimers.

Type 3 vWD shows a complete lack of multimers due to the inability to synthesize vWF in these patients.

Currently, this test is sent to an external reference laboratory and is not performed in the Hemostasis and Thrombosis Laboratory.