Kininogen deficiency in Fitzgerald trait: role of high molecular weight kininogen in clotting and fibrinolysis.

Plasma from an asymptomatic person with defects in blood coagulation, release of kinin, and evolution of fibrinolytic activity upon contact with a foreign surface was deficient in kininogen. The coagulation defect was identified as "Fitzgerald trait." A preparation of high molecular weight kininogen repaired the defects in clotting, kinin release and fibrinolysis, but a preparation of low molecular weight kininogen did not. Therefore, Fitzgerald factor appears to be a high molecular weight kininogen. The site of action of the kininogen appears to be after that of activated Hageman factor and kallikrein in the generation of clot-promoting activity through activation of plasma thromboplastin antecedent (PTA).