Fibrinogen 'New York'. An abnormal fibrinogen associated with thromboembolism: functional evaluation

A 54 yr old woman presented with a 23 yr history repeated life threatening thromboembolism. The presence of a qualitatively abnormal fibrinogen was suggested by the demonstration of delayed and incomplete coagulation of plasma or partially purified fibrinogen by thrombin or Reptilase. Two brothers showed a similar in vitro defect but were clinically not affected. The plasma fibrinogen concentration was 0.50 to 1.64 mg/ml when estimated by heat turbidity, clottability, or immunologic techniques. The serum contained 80 to 820 μg/ml of unclottable fibrinogen related materials even after 24 hr exposure to thrombin. The fibrinogen related material in the serum showed faster anodal mobility on immunoelectrophoresis than that of normal plasma. Immunodiffusion studies with rabbit antihuman fibrinogen antiserum showed lines of identity between control plasma and the patient's plasma and serum. Studies of the kinetics of thrombin action on fibrinogen demonstrated impaired release of fibrinopeptide A and B defective polymerization of preformed fibrin monomers. The maximum amount of fibrinopeptide A released by exhaustive treatment with thrombin was similar (per milligram protein) for both the patient's and control fibrinogen. This abnormal fibrinogen variant is tentatively designated fibrinogen 'New York', its possible identity with one of the previously described abnormal fibrinogens has not been excluded.