title: von Willebrand factor: evidence for variable clearance in vivo according to Y/C1584 phenotype and ABO blood group.
abstract: BACKGROUND
  The plasma von Willebrand factor (VWF) level (VWF:Ag) is known to correlate with the VWF Y/C1584 variation and with ABO blood group. The ratio of the VWF propeptide (VWFpp) to VWF:Ag and the ratio of coagulation factor VIII (FVIII:C) to VWF:Ag have previously been used as indicators of VWF clearance and/or secretion.
  
  
  OBJECTIVE
  To investigate the mechanism underlying the relationship between VWF phenotype and VWF:Ag, the VWFpp/VWF:Ag ratio and FVIII:C/VWF:Ag ratio were determined for plasmas of phenotype Y/C1584, Y/Y1584, blood group O and blood group A (n = 50 for each set). The blood group O plasmas comprised two sets of 25 with low and high mean VWF levels (Low-O and High-O), respectively; similarly for group A (Low-A and High-A).
  
  
  CONCLUSIONS
  The VWFpp/VWF:Ag ratio was greater than 1 (unity) for Y/C1584 plasmas and significantly higher than for Y/Y1584 plasmas; however, the FVIII:C/VWF:Ag ratio was near unity for both and was not significantly different. These results are consistent with increased clearance for Y/C1584 VWF. Similarly, the VWFpp/VWF:Ag ratio and FVIII:C/VWF:Ag ratio in combination were consistent with increased VWF clearance in blood group O compared with blood group A, and in Low-O and Low-A, respectively, compared with High-O and High-A. The data indicate that in vivo C1584 and blood group O are associated with increased VWF clearance, and that clearance contributes to differing VWF level within a given blood group.
authors.affiliation: Department of Haematology, School of Medicine, Cardiff University, Heath Park, Cardiff, UK.
authors.forename: J A
authors.initials: JA
authors.lastname: Davies
authors.forename: P W
authors.initials: PW
authors.lastname: Collins
authors.forename: L S
authors.initials: LS
authors.lastname: Hathaway
authors.forename: D J
authors.initials: DJ
authors.lastname: Bowen
mesh_terms: D000017:ABO Blood-Group System; D005169:Factor VIII / Q000032:analysis; D005838:Genotype; D006801:Humans; D020125:Mutation, Missense; D010641:Phenotype; D011110:Polymorphism, Genetic; D014841:von Willebrand Factor / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000017:ABO Blood-Group System; D014841:von Willebrand Factor; D005169:Factor VIII