Fibrinogen Milano II: a congenital dysfibrinogenaemia associated with juvenile arterial and venous thrombosis

A congenitally abnormal fibrinogen was isolated from blood of a young man with deep-vein thrombosis. Two other affected members of this family had three episodes of severe arterial thrombosis. The fibrinogen showed a delayed clotting by thrombin, but a normal clotting by Arvin®, Reptilase®, and prothrombin-staphylocoagulase complex. Analysis of the fibrinopeptides A and B by high performance liquid chromatography did not reveal an abnormal peptide structure. The rate of release of A and B peptides by thrombin was strongly delayed, whereas the rate of release of fibrinopeptide A by Arvin® appeared to be normal. The fibrin polymerization rate was normal. Interactions between the abnormal fibrinogen, platelets and the fibrinolytic interaction between fibrinogen Milano II and thrombin is associated with a defective binding of thrombin to the fibrin moiety of the abnormal fibrinogen.