Fibrinogen Zurich I: impaired release of fibrinopeptide A.

Fibrinogen Zurich I is characterized by an abnormal fibrin monomer polymerization. It consists of two fractions of molecules, one with a normal aggregation and one not aggregating at all and interfering with the aggregation of the normal population. Using a radioimmunoassay for fibrinopeptide A, only approximately half of the expected fibrinopeptide A could be recovered after thrombin or Defibrase proteolysis. The defective fibrinopeptide A release could be confirmed by measurement of the N-terminal Gly/Tyr ratio. It is likely that the abnormal fibrin monomer aggregation of the abnormal fraction of fibrinogen Zurich I is due to the defective fibrinopeptide A release of this fraction.