Associated von Willebrand disease as a possible cause of lack of thrombosis in an AT III abnormality (AT III Trento).

In a family with a known antithrombin III abnormality (AT III Trento) an associated von Willebrand defect (Type I) was found. The two defects seem to segregate independently. In fact four types of individuals were present, namely: subjects with isolated AT III abnormality, subjects with isolated von Willebrand defect, patients with double defect and normal subjects. Only one of the two patients with isolated AT III abnormality showed a thrombotic tendency. None of the patients with double defect showed thrombotic disease, indicating a possible protective action of the von Willebrand defect against thrombotic manifestations. Patients with isolated von Willebrand defect showed neither thrombotic nor bleeding manifestations. The study emphasizes the need for a careful evaluation of the hemostatic balance of patients with AT III abnormalities before concluding that they are symptomatic or asymptomatic.

Behaviour of antithrombin III abnormalities in the crossed immunoelectrophoresis system.

Antithrombin III (AT III) abnormalities can be characterized by means of crossed immunoelectrophoresis. In the past, it was thought that the abnormalities could be demonstrated only if heparin is present in the system. Now some conditions (AT III Trento, for example) are known to show an abnormal pattern only in the absence of heparin. This indicates that some of the changes are heparin-independent. Furthermore, it could be demonstrated that in some cases the abnormality is present only in serum (AT III Vicenza, for example). Therefore, the test should be carried out as a screening procedure both in plasma and serum and in the presence or absence of heparin in every case of suspected AT III abnormality.

Excess of factor X antigen versus clotting counterpart in coumarin treated patients as determined by an Elisa method.

Factor X antigen was assayed by means of an Elisa (sandwich) method in 36 patients on long-term anticoagulant therapy. The average value observed was 31.4% +/- 12.2. In almost every instance the antigen level was higher than the clotting counterpart (14.4% +/- 4.5). In a few instances no major difference was noted between factor X antigen and factor X activity. The method correlated fairly well with other immunological methods (electroimmunoassay and Laser Nephelometer). Therefore, factor X Elisa method appears to be a suitable method for factor X antigen evaluation.

Antithrombin III Trento. A 'new' congenital AT III abnormality with a peculiar crossed-immunoelectrophoretic pattern in the absence of heparin.

A family with a new congenital abnormality of antithrombin III (AT III) is presented. 5 members, all females, were affected. The proposita has had several thrombotic manifestations. The other patients, so far, are asymptomatic. Antithrombin activities were all decreased regardless of the method used (chromogenic or clotting) and regardless of the presence or absence of heparin in the assay system. AT III antigen, on the contrary, was normal in all patients regardless of the method used (electroimmunoassay, radial immunodiffusion or Laser nephelometer). The crossed immunoelectrophoresis without heparin showed in plasma the presence of an abnormal peak which was more anodal than the normal counterpart. The same pattern was seen in serum. In the heparin-modified cross-immunoelectrophoresis a normal pattern was seen in plasma and an abnormal one in serum. In the latter the anodal peak was in fact larger than the normal counterpart. Chromatographic studies using Heparin-Sepharose column failed to show changes in heparin affinity, and indicated that both the normal and the abnormal proposed to describe this abnormality. These studies further emphasize the great heterogeneity of AT III defects. This is the first AT III abnormality to show an abnormal crossed-immunoelectrophoresis in the absence of heparin.