The relationship between ABO blood subgroups and the circulating levels of von Willebrand factor and factor VIII

Abstract Von Willebrand factor (VWF) is produced inendothelial cells and megakaryocytes, and is secreted intoplasma as a multimeric glycoprotein. VWF plays a key rolein primary hemostasis, acting as a mediator betweenspecific receptors on the platelet surface and componentsof the extra cellular matrix such as collagen. Additionally,it serves as a carrier and stabilizing protein for procoagulantfactor VIII. Various factors influence the plasma level ofFVW:Ag (VWF antigen), and ABO is one of the mostimportant of these factors. Several authors have shownthat normal group O individuals have significantly lowerlevels of VWF and factor VIII than non-O individuals.Furthermore, recent studies have demonstrated that nor-mal individuals carrying one O allele (AO and BO) havesignificantly lower plasma levels of VWF and factor VIIIthan those carrying no O allele (AA, AB and BB). Thereare no reports in the literature regarding the functionalactivity of VWF in blood subgroups A 2 O, A B, A 3 O, A X