Ultimately, thorough VWD testing should include measurement of VWF levels (VWF:Ag) and determination of each aspect of function: Specifically, the interaction with platelet glycoprotein 1b (VWF:RCo), as well as subendothelium-collagen interactions (VWF:CB), evaluation of FVIII activity, and in some circumstances multimer analysis 32. This evidence concerns the gene VWF and von Willebrand disease (hereditary or acquired).