Fibrinogenemia Tampere. A dysfibrinogenemia with defective gelation and thromboembolic disease

Abstract Fibrinogen Tampere was found in a woman with a severe thromboembolic disease. The thrombin induced clotting time of her plasma and purified fibrinogen was slightly prolonged. The activation of fibrinogen Tampere appeared to be normal but subsequent gelation was defective. We studied fibrin gels formed at different ionic strengths and at different fibrinogen and calcium concentrations by liquid permeation, turbidity, and 3D laser microscopy. Crosslinking was studied by SDS-gel electrophoresis. The gels formed from fibrinogen Tampere were at inoic strength above 0.2 much tighter and had lower fiber mass-length ratios than normal gels as judged by permeability and turbidity data. At ionic strength 0.15 and at different calcium concentrations analysis by permeability showed the same results for fibrinogen Tampere as for normal gels. Analysis by turbidity at ionic strength 0.15 suggested swelling of the fibers at low calcium concentrations. 3D microscopy revealed perturbed clot architecture under all conditions. In fibrin gels from fibrinogen Tampere, the γ-chain crosslinking was normal but the crosslinking of α-chains was delayed at ionic strength 0.2 and also at lower ionic strengths on lowering the calcium concentration. The abnormal gelation may be due to a mutation in the fibrinogen molecule. Tendency to form tight fibrin gels and/or insufficient cross-linked fibrin matrix may be pathogenetic in this thrombotic disease.