title: Collagen binding provides a sensitive screen for variant von Willebrand disease.
abstract: BACKGROUND
  von Willebrand factor (VWF) is a multimeric protein that binds platelets and collagen, facilitating hemostasis at sites of vessel injury. Measurement of VWF multimer distribution is critical for diagnosis of variant von Willebrand disease (VWD), particularly types 2A and 2B, but the typical measurement by gel electrophoresis is technically difficult and time-consuming. A comparison of VWF collagen binding (VWF:CB) and VWF multimer distribution was performed to evaluate the utility of VWF:CB as a diagnostic test.
  
  
  METHODS
  Participants were enrolled in the Zimmerman Program for the Molecular and Clinical Biology of VWD. VWF:CB was analyzed with type III collagen and multimer distribution by agarose gel electrophoresis. The study population included 146 healthy controls, 351 individuals with type 1 VWD, and 77 with type 2 VWD. Differences between individuals with multimer group results within (controls) and outside the reference intervals were assessed with Mann-Whitney tests.
  
  
  RESULTS
  The mean VWF:CB/VWF antigen ratio was 1.10 for individuals with multimer distribution within the reference intervals and 0.51 for those with multimer distribution outside the reference intervals (P < 0.001). Sensitivity of VWF:CB for multimer abnormalities was 100% for healthy controls, 99% for patients with type 1, and 100% for patients with type 2A and type 2B VWD using a VWF:CB/VWF antigen cutoff ratio of 0.6, and decreased to 99% for all patients with a ratio of 0.7. With the exception of individuals with novel or unclassified mutations, the VWF:CB was able to correctly categorize participants with variant VWD.
  
  
  CONCLUSIONS
  These findings suggest that VWF:CB may substitute for multimer distribution in initial VWD testing, although further studies are needed to validate the clinical utility of VWF:CB.
authors: Department of Pediatrics, Division of Hematology and Oncology, Medical College of Wisconsin, Milwaukee, WI, USA. veronica.flood@bcw.edu
authors: Veronica H
authors: VH
authors: Flood
authors: Joan Cox
authors: JC
authors: Gill
authors: Kenneth D
authors: KD
authors: Friedman
authors: Pamela A
authors: PA
authors: Christopherson
authors: Paula M
authors: PM
authors: Jacobi
authors: Raymond G
authors: RG
authors: Hoffmann
authors: Robert R
authors: RR
authors: Montgomery
authors: Sandra L
authors: SL
authors: Haberichter
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D016022:Case-Control Studies; D003094:Collagen / Q000378:metabolism*; D006801:Humans; D011485:Protein Binding; D014842:von Willebrand Diseases / Q000145:classification / Q000175:diagnosis* / Q000378:metabolism
chemical_list: D015415:Biomarkers; D003094:Collagen