Detection of factor V leiden and prothrombin gene mutations in patients who died with thrombotic events

Prothrombin and risk of venous thromboembolism, ischemic heart disease and ischemic cerebrovascular disease in the general population

OBJECTIVE

We tested the hypotheses that Prothrombin G20210A heterozygosity associate with increased risk of venous thromboembolism (VTE), ischemic heart disease (IHD), and ischemic cerebrovascular disease (ICVD) in the general population and re-tested risk of IHD and ICVD in two case-control studies.

METHODS

9231 individuals from the Danish general population were followed for VTE (VTE=DVT+PE), deep venous thrombosis (DVT), pulmonary embolism (PE), IHD, myocardial infarction (MI), ICVD, and ischemic stroke (IS) for a median of 24 years. Case-control studies included 2461 IHD cases and 867 ICVD cases.

RESULTS

In the general population, Prothrombin G20210A heterozygotes had1.3 (95% CI:0.6-2.9) fold risk for VTE, 0.6 (0.2-2.0) for DVT, 1.7(0.6-4.8) for PE, 1.5(1.1-2.1) for IHD, 1.7(1.1-2.7) for MI, 1.1(0.6-1.9) for ICVD, and 1.1(0.5-2.1) for IS compared to non-carriers. Double heterozygotes for Prothrombin G20210A and Factor V Leiden versus double non-carriers had a multifactorially adjusted hazard ratio for IHD of 6.0(2.0-19). In case-control studies, multifactorially adjusted odds ratios for Prothrombin G20210A heterozygotes versus non-carriers were 2.0(1.1-3.4) for IHD, 2.0(1.0-3.8) for MI, 1.4(0.7-3.1) for ICVD, and 2.1(0.8-5.4) for IS.

CONCLUSION

Prothrombin G20210A heterozygosity alone and in combination with Factor V Leiden R506Q heterozygosity predicts 1.5 and 6.0 fold risk of IHD compared to non-carriers.

Comparative aspects of blood coagulation

Blood coagulation is a basic physiological defense mechanism that occurs in all vertebrates to prevent blood loss following vascular injury. In all species the basic mechanism of clot formation is similar; when endothelium is damaged a complex sequence of enzymatic reactions occurs that is localized to the site of trauma and involves both activated cells and plasma proteins. The reaction sequence is initiated by the expression of tissue factor on the surface of activated cells and results in the generation of thrombin, the most important enzyme in blood clot formation. Thrombin converts soluble fibrinogen, via soluble fibrin monomers, into the insoluble fibrin that forms the matrix of a blood clot as well as exerting positive-feedback regulation that effectively promotes additional thrombin generation that facilitates the rapid development of a thrombus. Both spontaneous and trauma-induced haemorrhagic episodes can develop in all mammals with inherited or acquired abnormalities in one or more of the coagulant proteins. Experimental studies with plasma from a wide range of species have led to the conclusion that there are extensive differences in the rates of thrombin generation and fibrin formation among species. However, current evidence suggests that at least some of these quantitative differences are likely due to the use of non-species specific laboratory reagents. Although the individual proteins involved in the procoagulant pathways exhibit similar functions in all animals, differences in amino acid sequence cause incomplete homology and varying degrees of immunological cross-reactivity for the same protein across species.