FAMILY STUDIES OF PATIENTS WITH RECURRENT VENOUS THROMBOSES AND INHERITED DISORDERS OF BLOOD COAGULATION OR FIBRINOLYSIS

Several defects of the coagulation and/or fibrinolytic system have been found to be associated with venous thromboembolism. In young patients with recurrent thromboses or a positive family history, an inherited disorder should be excluded

535 young patients with venous thromboses, phlebitis and/or pulmonary embolism were investigated from 1980 until 1986. The first thrombotic event had occurred at an age of less than 45 years.An inborn disorder of the blood coagulation or fibrinolytic system was found in 18 families. Most of them (n=13/18) had a positive family history. In all families either thromboses had occurred in at least one member (n=12/18) and/or the defect could be detected in one of them (n=12/18)

Most often we found a deficiency of antithfombin III (n=6). A deficiency of protein C (type I) was detected in 3 and a deficiency of protein S in 5 families. In one patient a combined deficiency of anti thrombin III, protein C and protein S was found. Extensive family studies revealed a deficiency of antithrombin III in the grandmother of the patient, who suffered from arterial thrombosis. A deficiency of plasminogen and an abnormal plasminogen molecule were detected in 2 other families. Defective release of t-PA could be demonstrated in 3 members of one investigated family up to now

Seme family members with either defects of protein C, protein S or plasminogen as well as a defective release of t-PA lack thrombotic events. Furthermore thromboses of mesenteric veins occurred in 2 of 6 patients with anti thrombin III deficiency and in 1 of 5 patients with protein S deficiency. Superficial vein thromboses were mainly found in patients with protein C- or protein S-deficiency