Effect of factor V^LEIDEN in the case of severe hemophilia A. Thrombin formation in the absence of factor VIII in the presence of protein C and 1 nmol/L thrombomodulin with either normal factor V (triangles), a mixture composed of 50% normal factor V and 50% factor V^LEIDEN (squares), or 100% factor V^LEIDEN (circles). Thrombin generation was initiated by 5 pmol/L factor VIIa⋅TF. Error bars represent the standard error of mean (n = 3).