Genetics of plasma concentration of von Willebrand factor.

The plasma concentration of von Willebrand factor (vWf) shows a very wide range in individuals without bleeding disorders. In a twin study we found that 60% of the variance of the plasma concentration of vWf is due to genetic factors. Individuals with AB0 blood group 0 have a lower concentration of vWf than individuals with blood group A, B or AB. Thirty percent of the genetic variance was due to an effect of the AB0 locus. Since the Lewis substances show great structural similarity to the ABH blood group substances we compared the vWf concentration in individuals with and without the Lea antigen on the red cell surface. Individuals lacking the Lea antigen had a lower vWf concentration than individuals who had this antigen. Le(a+b-) people are nonsecretors and Le(a-b+) people are secretors of ABH substance. The lowest vWf concentration was found in blood group 0 secretors. Both the AB0 locus and the Secretor locus may be major loci for the determination of the plasma concentration of vWf.