Fibrinogen Barcelona I. Congenital dysfibrinogenemia characterized by defective release of fibrinopeptide A and fibrinogen degradation products.

A congenital dysfibrinogenemia, fibrinogen Barcelona I, was detected in a 28 year-old woman with no prior history of bleeding. The thrombin induced clotting of plasma and purified fibrinogen was much prolonged. Fibrin monomer aggregation was impaired. The abnormal fibrinogen polymerized in the presence of calcium and can be further cross-linked by factor XIIIa. The turbidity of fibrin gels obtained from fibrinogen Barcelona was much lower than normal fibrinogen. The kinetic constant Km for fibrinogen Barcelona plus normal fibrinogen gelation was similar to normal fibrinogen gelation. The release rate of fibrinopeptide A by thrombin was slower than that of normal fibrinogen. However, two mol of fibrinopeptide A was released per mol of fibrinogen in 30 min. SDS-PAGE of abnormal and normal fibrinogens and of reduced fibrinogens showed identical patterns. Sialic acid content was markedly decreased in fibrinogen Barcelona. Plasmin digestion of two fibrinogens showed identical patterns in SDS-PAGE as regards X fragment formation. The kinetics of fibrinogen degradation showed a decrease in the formation rate of D and E fragments. The fact that the patient was in threat of abortion and developing a haemorrhagic syndrome may indicate that the defect in the fibrinogen was important in the pathogenesis of haemorrhage in this patient.