Measurement of von Willebrand factor activity: relative effects of ABO blood type and race

Abstract

Summary. Tests based on three different principles are reported to measure the activity of von Willebrand factor (VWF): ristocetin cofactor (VWF:RCo), collagen binding (VWF:CB), and the so-called`activity ELISA' (VWF:MoAb). We measured these and other diagnostic parameters in a population of 123 randomly selected female study controls, age 18±45 years. Type O subjects had signi®cantly lower levels than non-O subjects in each test. Race differences were seen in all tests except VWF:RCo, with Caucasians having signi®cantly lower levels than African-Americans. ABO differences accounted for 19% of the total variance in VWF:Ag (P < 0.0001) and race for 7% (P < 0.0001), for a total of 26%. Both effects were mediated through VWF:Ag and were independent. VWF:Ag level was the primary determinant of VWF function, accounting for approximately 60% of the variance in VWF:RCo and VWF:CB and 54% of the variance in factor VIII. The ratio VWF:RCo/ VWF:Ag differed signi®cantly by race within blood group. The median ratios were 0.97 for type O Caucasians vs. 0.79 for type O African-Americans and 0.94 for non-O Caucasians vs. 0.76 for non-O African-Americans. The ratio VWF:CB/VWF:Ag did not vary. This suggests racial differences in the interaction of VWF with GP1b but not with subendothelium. Alternatively, VWF:RCo may be regulated to maintain a relatively constant plasma level in the presence of excessive VWF:Ag. This heterogeneity within the normal population is partially responsible for the dif®culty in de®ning diagnostic limits for von Willebrand disease.

Plasma von Willebrand factor level and its associated parameters: Reference ranges in Nigeria

“…VWF: CB was significantly lower in blood group O when compared with non-O blood. This is consistent with the observation in the Chinese population (Chng et al, 2005), Australia (Favaloro et al, 2005) and Atlanta (Miller et al, 2003). In this study, we also demonstrated a significant correlation between VWF: Ag and VWF: CB in blood group O subjects.…”

“…The actual ranges quoted by earlier reports varied greatly, this may be attributed to the genotype of the ABO blood group and other factors outside the VWF gene. The ranges determined in this study were higher when compared with Caucasian values determined by Miller et al (2003). This may be explained because VWF is an acute phase reactant in man and our population is exposed to many conditions including malaria infestation that can predispose to an inflammatory response.…”

“…Plasma VWF vary relative to ABO blood group and race (Coppola et al, 2003;Miller et al, 2003;Sukhu et al, 2003;Haley et al, 2002;O'Donnell and Laffan, 2001;Miller et al, 2001;Nitu-Whalley et al, 2000;Shima et al, 1995;Caekebeke-Peerlinck et al, 1989). Also, ABO blood group influences the rate of proteolysis of VWF by ADAMTS-13 (Bowen, 2003) and show relationship between thrombotic and coronary risk factor (Schleef et al, 2005;Ray et al, 2004).…”

“…Selection of the normal range for VWF plasma level at the lower end of the reference range based on the ABO group might influence the clinical diagnosis of VWD. (Bauduer and Ducout, 2004;Miller et al, 2003). At the upper end of the range, there is increased evidence of elevated thrombosis risk with high level of VWF (van der Meer et al, 2004;Felmeden et al, 2003).…”

The ABO Histo-Blood Group and AKI in Critically Ill Patients with Trauma or Sepsis

“…Alternatively, an unidentified genetic or environmental factor, with distinct frequencies between individuals of European and African descent, may modify the ABO-AKI association depending on race. For example, polymorphisms in the vWF gene are associated with expression of vWF in healthy Americans of European but not African descent, suggesting racial divergence in the genetic regulation of vWF expression (46,47) and possibly, contributing to the racial difference in ABO-AKI associations. The baseline characteristics of our cohorts also exhibit racial differences.…”