A NEW THROMBOTIC DYSFIBRINOGENEMIA PRESENT IN SEVERAL MEMBERS OF A VENEZUELAN FAMILY

Up to the present, 16 dysfibrinogenemias have been described with thrombotic symptomatology, of which 3 cases showed low affinity of the fibrin for thrombin.

In this study, we describe a family with an elevated frequency of thrombotic episodes which may be due to an alteration in the fibrinogen molecule causing a defective adsorption of thrombin by the fibrin formed.

Two women, mother and daughter, were admitted to our clinic with a history of repeated pulmonary thromboembolisms. Coagulation studies (which included Antithrombin III, Protein C, etc.) revealed only a prolonged thrombin time with high fibrinogen levels (500 mg/dl) by the clot weight and immunological methods. More detailed studies on fibrinogen function showed:

1) Abnormal monomers aggregation and polymerization rate, ho changes were observed in the latter when induced by reptilase followed by thrombin.

2) Normal fibrinopeptide release

3) Normal cross-linked and uncross-linked fibrin chains.

4) Low affinity of fibrin for thrombin

5) Normal plasmin degradation

6) The electron microscopy showed a normal fibrin net with the characteristic periodic cross-striations pattern but which formed more slowly than normal.

Both patients were treated with oral anticoagulants. The mother has not suffered any thromboembolic episodes in two years of treatment but the daughter has shown clinical signs of minor episodes of pulmonary thromboembolism which were confirmed by perfussion gammagraphy. In the family study, 4 members have died due to either venous or arterial thrombotic accidents. Fibrinogen function studies carried out on 8 members from 3 generations showed a prolonged thrombin time with delayed polymerization in 4 of the 8 (1 adult, 3 children), none of which have suffered any thrombotic manifestations up to the time of the study.

The name of Caracas V is proposed for this new dysfibrino-genemia.