Abstract
Von Willebrand factor is a glycoprotein produced in the endothelium and megakaryocytes. Its levels are known to vary between individuals. About 60% of the variations are caused by genetic factors with ABO blood group accounting for about 30%. This research was carried out to determine von Willebrand factor antigen (vWf:Ag) levels in different ABO blood groups in a Nigerian population. Blood samples were collected from 207 apparently healthy residents of Calabar, Nigeria,for the determination of ABO blood group phenotypes and vWf:Ag levels. The subjects were aged between ten and seventy years. Both male and female subjects were involved. ABO blood group phenotype was determined by standard tube method while vWf:Ag was determined by ELISA method. The result showed that 48 (23.2%) of the subjects were of blood group A, 48 (23.2%) belonged to group B, 5 (2.4%) were of group AB, while group O subjects constituted 106 (51.2%) of the subjects. The mean vWf:Ag for all the subjects was 93.79 ±26.2%. Group A had mean value of 101.38 ± 24.26%, group B had 110.63 ± 21.36%, group AB had a level of 104.60 ± 24.17% and group O had a mean value of 82.23 ± 26.28%. A comparison of the mean levels between group O and non-group O individuals showed that non-group O had significantly higher levels than group O (p<0.05). The male in this study had mean vWf:Ag level of 91.43 ± 24.85% while the female subjects had a value of 96.09 ± 27.54%. The subjects aged 10-30 years had vWf:Ag level of 92.81 ± 25.90%, those between 31-50 years had mean value of 93.2 ± 27.64% while subjects aged 51-70 years of age had mean vWf:Ag level of 108.73±18.18%. This study has shown that vWf:Ag is higher in non-group O than blood group O individuals and that sex does not affect the level of
vWf:Ag.
Key words: Von Willebrand factor, von Willebrand factor antigen, ABO blood groups, Nigeria