The prothrombin nt20210 A allele as a risk factor for venous thromboembolism: detection of heterozygous and homozygous carriers by alternative methods.
Factor V Leiden is a genetic disorder characterized by a poor anticoagulant response to activated Protein C and an increased risk for venous thromboembolism.
Technical standards and guidelines: venous thromboembolism (Factor V Leiden and prothrombin 20210G >A testing): a disease-specific supplement to the standards and guidelines for clinical genetics laboratories.
According to the Lyon-venous thromboembolism risk score, 50% of patients with PC deficiency and 51% of heterozygous factor V Leiden carriers did not received any antepartum heparin prophylaxis.
The odds ratio for the FII 20210G/A mutation in 504 patients with venous thromboembolism compared to controls was 2.0 (95% CI 1.0-4.0) and, for factor V Leiden, 5.8 (95% CI 3.3-10.3).
We have analyzed 5971 control individuals originating from 26 geographically defined populations in Europe and neighboring countries for the presence of factor V Leiden, an important genetic risk factor in venous thromboembolism.
In contrast, factor V Leiden, the G20210A prothrombin gene mutation, and the C677T MTHFR gene mutation are not genetic risk factors among Thai patients with VTE.
Prothrombin 19911 A > G polymorphism was independently associated with a 1.5-fold increased risk of VTE and increased 2-fold the risk of VTE associated with FV Leiden, both increases statistically significant.
The aim of this study was to compare the prevalence of the prothrombin 20210A allele in control subjects and in subjects with recognised thrombophilia and to establish whether the additional inheritance of the PT 20210A allele is associated with an increased risk of venous thromboembolism.
Coagulation factor II G20210A and coagulation factor V (Leiden) G1691A single nucleotide polymorphisms (SNPs) are major inherited risk factors of venous thromboembolism.
Within the past decade, the identification of two mutations that are relatively prevalent among the white population (the factor V Leiden and prothrombinG20210A gene mutations) has paved the way for a number of large cohort studies that have greatly advanced our understanding of the pathogenesis of venous thromboembolism (VTE).
Active cancer was associated with at increased risk for VTE recurrences (HR: 3.06; 95%CI: 1.14-8.17) and anaemia (HR: 4.11; 95%CI: 1.45-11.6) or abnormal prothrombin time (HR: 4.10; 95%CI: 1.68-10.1) were associated with at increased risk for major bleeding.
Symptomatic venous thromboembolism (VTE) during prophylaxis and follow-up (1.9%) was significantly over-represented among patients with the prothrombin gene G20210A mutation (p = 0.0002).
Trial endpoints will include recurrent VTE, major bleeding episodes and all-cause mortality in the total patient population and separately in those patients with factor V Leiden.
Further clinical trials are also required to determine if a longer course of treatment is indicated for subgroups of patients based on clinical characteristics and laboratory features (such as those with idiopathic thrombosis versus postoperative thrombosis, and those with or without identifiable molecular markers of a high risk of recurrent venous thromboembolism such as the factor V Leiden gene mutation).
Inherited thrombophilia was not associated with a statistically significant increase in risk of recurrence in pregnancy or in puerperium, yet the rate of recurrence in puerperium was 14.2% (95%CI 5.7-31.4) in overall carriers of factor V Leiden and 30% (95%CI 10.7-60.3) in carriers with a pregnancy-related first VTE, with a risk 6.8 times higher than in women without thrombophilia and with a non pregnancy-related first VTE.
Single point mutations in the genes coding for factor V [G1691A; Leiden], prothrombin [PRT; G20210A], and methylenetetrahydrofolate reductase [MTHFR, C677T] were shown to be major inherited predisposing factors for venous thromboembolism.
The most accepted inherited hemostatic abnormalities associated with venous thromboembolism are factor V Leiden (FVL) and factor II (FII) G20210A mutations, as well as deficiencies in antithrombin (AT), protein C (PC), and protein S (PS).