Hereditary defects in fibrinolysis associated with thrombosis.

The plasminogen-plasmin system involves proteolytic enzymes which are primarily responsible for the degradation of fibrin deposits in blood vessels. Through intricate interactions between the various components and inhibitors, a balance is maintained between profibrinolysis and impaired fibrinolytic activity. Several hereditary defects have been described affecting functional plasminogen concentrations, plasminogen activator levels, and plasminogen activator inhibitor activity. These defects have been implicated as risk factors for thrombosis based on a multitude of case reports associating impaired fibrinolysis with thrombosis. However, under close scrutiny, the role of decreased fibrinolysis as an etiologic factor in thrombosis has not been firmly established. Rather, dysfibrinolysis may manifest itself through an accentuation of an underlying thrombophilic state such as recurrent thrombotic episodes. Further evaluation of impaired fibrinolytic activity in conjunction with an underlying thrombophilic condition is warranted.