Clinical and biochemical characterization of the prothrombin Belgrade mutation in a large Serbian pedigree: new insights into the antithrombin resistance mechanism

Abstract

Background The recently reported c.1787G>A mutation in the prothrombin gene leads to Arg596Gln replacement in the protein molecule (prothrombin Belgrade). This substitution impairs binding of antithrombin to thrombin and results in inherited thrombophilia, known as antithrombin resistance. Objectives We aimed to elucidate the clinical and biochemical characteristics of thrombophilia associated with antithrombin resistance in a large Serbian family with the prothrombin Belgrade mutation. Patients and methods Nineteen family members were investigated, among whom 10 were carriers of the c.1787G>A mutation. In all subjects the clinical phenotype was determined and laboratory investigations of hemostatic parameters were performed. Results Six out of the 10 mutation carriers developed thromboembolic events, mainly deep venous and mesenteric vein thrombosis. The median age of the first thrombotic event was 26.5 (12-41) years, whereas the incidence rate of first thrombosis was 2.2% per year. In all mutation carriers prothrombin activity was significantly decreased in comparison with non-carriers, clearly distinguishing each group. However, the presence of the mutation did not affect the prothrombin antigen level in plasma. The endogenous thrombin potential was significantly increased in all carriers in comparison with non-carriers, indicating the presence of blood hypercoagulability. Interestingly, levels of D-dimer and the F1+2 fragment were similar in both groups. Conclusions Although rare, the prothrombin Belgrade mutation represents strong thrombophilia with early onset of thrombosis in the investigated family. According to our results, decreased prothrombin activity may be a simple screening test for detection of this mutation in thrombotic patients.

Screening and functional exploration of prothrombin Arg596 related mutations in Chinese venous thromboembolism patients

“…All VTE-causing prothrombin mutations including Arg596Gln, Arg596Trp and Arg596Leu were reported to decrease prothrombin clotting activity. We found that deceased prothrombin activity was a simple and valuable test for screening Arg596 associated mutation as previously mentioned,12 and decreased prothrombin activity warrants further genetic analysis of the F2 gene.…”

Optimisation of antithrombin resistance assay as a practical clinical laboratory test: Development of prothrombin activator using factors Xa/Va and automation of assay

“…The thrombotic clinical penetrance of antithrombin‐resistant prothrombinemia is estimated to be equivalent or higher than that of antithrombin deficiency. With respect to prothrombin Belgrade (Arg596Gln), 60% heterozygous carriers of this mutation in the reported family developed venous thrombosis during their lifetime, and the annual incidence rate of the first thrombosis from birth was 2.2% . Conversely, the prevalence of an antithrombin‐resistant prothrombin carrier with this mutation has not been precisely estimated among patients with VTE.…”

“…Antithrombin‐resistant prothrombin is a mutant presenting paradoxical features in thrombosis and haemostasis in vivo, that is the mutant thrombin derived from antithrombin‐resistant prothrombin displays a mild decline in the procoagulant activity. However, a substantial impairment in its inactivation by antithrombin results in a prolongation of the procoagulant activity, causing thromboembolism in some patients . In clinical laboratory tests, plasma from the patient with a heterozygous ATR mutation does not exhibit a significant alteration in PT and APTT levels .…”

“…Diagnosis of antithrombin‐resistant prothrombin depends on a history of provoked or unprovoked VTE and subsequent definitive gene sequencing. Global coagulation tests (eg prothrombin time or activated partial thromboplastin time) cannot detect the antithrombin‐resistant prothrombin abnormality in heterozygote patients . Previously, we have established a manual operation assay specialised in detecting ATR .…”

“…Global coagulation tests (eg prothrombin time or activated partial thromboplastin time) cannot detect the antithrombinresistant prothrombin abnormality in heterozygote patients. 10,12,15 Previously, we have established a manual operation assay specialised in detecting ATR. 16 This manual operation assay has a prothrombin activator step by Oxyuranus scutellatus (Ox) venom; however, currently, it is difficult to obtain Ox venom because it is not marketed in some countries including Japan.…”