Studies on the inheritance and nature of hemophilia BM

Incidence, significance, and subtypes of hemophilia BM in a large population of hemophilia B patients

Eleven patients with hemophilia BM were found out of a population of 66 patients with hemophilia B. Factor IX activity in the hemophilia BM varied between less than 1% and 1.6% of normal but factor IX antigen was normal or only slightly reduced in each instance. Thrombotest clotting time was variably prolonged and was not corrected by the addition of normal plasma. Thrombotest mixing experiments and dilution curve studies confirmed the presence of the inhibitor in every patient. There are at least two forms of hemophilia BM, a severe one and a mild one. In the first form, Thrombotest is severely prolonged (90-120 s). In the other, the prolongation is mild or moderate (60-80 s). A positive correlation exists between the antigen-activity difference (delta antigen-activity) and the prolongation of Thrombotest both in the propositi and in obligatory carriers. The criteria for the diagnosis of hemophilia BM are the following: prolonged PTT, prolonged Thrombotest, lack of correction of Thrombotest by the addition of normal plasma while PTT is fully corrected. The lack of correction of Thrombotest in the presence of a full correction of PTT, is the unique clotting feature.

[Clinical studies of familial hereditary factor VII deficiency (author's transl)]

The discovery of a severe factor VII deficiency with increased bleeding tendency resulted in investigations of 22 members of the family. In the propositus and in two of his siblings a severe hypoproconvertinemia was demonstrated, a partial deficiency was found in ten persons. Studies of the family confirmed that this disorder is transmitted by an autosomal gene with intermediate penetrance. The mutated gene produces a severe deficiency in the homozygote and partial deficiency in the heterozygote. The parents of the homozygote patients were consanguineous. Hemorrhagic diathesis was noted only in patients with a severe factor VII deficiency. Causes for the variability of the clinical manifestations are discussed.

New methods in coagulation

Recent advances in the elucidation of the molecular biochemistry of the coagulation proteins have provided the foundation for the development of synthetic substrates. These substrates are oligopeptide with either a chromophore or fluorophore group attached to the C-terminal end. They may be used in the laboratory to assay for a number of the serine proteases involved in either coagulation or fibrinolysis. Also, by suitably modifying the assay system, the various inhibitors can be quantitated. These substrates promise to revolutionize the coagulation laboratory allowing for more precise quantitation of trace enzymes and also improved standardization and precision of coagulation assays. In addition to these substrates, the introduction of a number of immunologic procedures into the diagnostic laboratory have been of major importance in elucidating the heterogeneity of hereditary coagulation defects. By correlating the immunologic assays, coagulation assays and clinical picture, a number of subgroups of hereditary deficiencies have been identified. Also, the immunologic assays have provided a means for identifying the carrier state of hemophilia A and have significantly contributed to the improved diagnosis of von Willebrand's disease. The use of ristocetin cofactor assays, when used in conjunction with the Factor VIII antigens, have enable the laboratory to more accurately diagnose the majority of patients with von Willebrand's disease. Ristocetin cofactor may be assayed utilizing either formalin fixed or washed platelets and recently a snake venom has been introduced to assay for this particular aspect of the Factor VIII complex. Platelet specific proteins (i.e., platelet factor 4 and beta-thromboglobulin) may be assayed utilizing either radioimmunoassays or in the case of platelet factor 4 modified coagulation assays. These proteins provide evidence of in vivo platelet activation and hopefully may, in the future, be correlated with platelet kinetics.