How Old Is Factor V Leiden Mutation?

High prevalence of factor V Leiden and prothrombin G20101A mutations in Kashmiri patients with venous thromboembolism

AIM

The genetic variants of the factor V (G1691A), prothrombin (G20210A) and MTHFR (C677T) genes have been widely implicated as inherited risk factors for developing venous thrombosis. This study was undertaken to reveal the frequency of these mutations in Kashmiri patients with venous thromboembolism.

METHODOLOGY

A case-control study was designed with 250 VTE patients and 250 healthy controls. The mutations were analysed using ARMS-PCR and PCR-RFLP approach.

RESULT

The factor V Leiden G1691A mutation was found in 17/250 (6.8%) VTE patients and prothrombin G20210A mutation was found in 7/250 (2.8%) VTE patients while no mutation was found in any of the healthy controls. Both the mutations were found to be significantly associated with the increased risk of VTE (p = 0.0001 and 0.0150 respectively) while no association of VTE risk with MTHFR C677T polymorphism was found (p = 0.53).

CONCLUSION

The increased frequency of factor V Leiden G1691A and prothrombin G20210A mutation in VTE patients indicates a significant role of these mutations in the development of VTE in our population. We therefore suggest the routine screening of these two mutations as thrombophilic markers in Kashmiri patients with venous thromboembolism.

Race differences in the prevalence of the factor V Leiden mutation in Kuwaiti nationals

Factor V Leiden mutation (FVL; G1691A) is an established risk factor for venous thromboembolic disorders. FVL was reported with high prevalence in Caucasians (1-15%) but was absent in non-Caucasians like Africans and Asians. Studies reported FVL in 5-27% of Arabs and non-Arabs living in the Middle Eastern countries northern to the Arabian Peninsula, but was almost absent in Arabs in the Arabian Peninsula itself. Kuwait is an Arabic country present on the northern border of the Arabian Peninsula, and Kuwaitis are originally from Saudi Arabia (Southern to Kuwait and within the Arabian Peninsula) or from Iran and Iraq (northern to Kuwait and the Arabian Peninsula). This study was conducted to study FVL in Kuwaitis in relation to their origin. Real-time PCR was performed on DNA samples of 285 apparently healthy Kuwaitis using specially designed primers and probes for FVL. There were 109 Kuwaitis of Iranian origin, 71 of Iraqi origin and 105 of Saudi origin. FVL was present in 7 and 5 Kuwaitis of Iranian and Iraqi origin, respectively. None of the Kuwaitis of Saudi origin had the mutation. Prevalence of FVL in Kuwaitis of Iranian (6.42%) and Iraqi (7.04%) origin were statistically different from prevalence in Kuwaitis of Saudi (0%) origin (P-value<0.05). No difference was found between females and males (P-value>0.6). In conclusion, FVL is present in Kuwaitis of Iranian or Iraqi origin only. Therefore, testing and providing genetic consultation for FVL may be needed in those Kuwaitis only which should save time, cost and efforts. However, this assumption should be confirmed by other studies and on larger number of cases.

Thrombophilic gene polymorphisms in puerperal cerebral veno-sinus thrombosis

Puerperal cerebral veno-sinus thrombosis (PCVT) is a common form of stroke in young women in India, which is associated with high morbidity and mortality. The frequency of PCVT in India is 10 to 12 times more compared to western population. As yet, the etiology of this condition is unclear. Our aim was to study the prevalence and the role of the common genetic polymorphisms associated with thrombophilia such as factor V Leiden, prothrombin G20210A and methylene tetrahydrofolate reductase (MTHFR) C677T, in aseptic PCVT. We investigated 86 women with PCVT and 86 age-matched women with no post-partum complications. Polymerase chain reaction (PCR)/restriction fragment length polymorphism analysis was used to identify their genotypes. The frequency of the three polymorphisms in cases and controls were: factor V Leiden, 2.3% versus 1.2% (OR 0.49, 95% CI=0.02-7.12, p=1.000) and MTHFR C677T, 16.3% versus 17.4% (OR 0.92, 95% CI=0.39-2.19, p=0.838). The prothrombin G20210A variant was not detected in either patients or controls. The clinical characteristics of the PCVT patients with the polymorphisms did not differ significantly from those without them. In our series of PCVT patients, the risk associated with the established thrombophilic risk factors is insignificant. Exploration of these gene polymorphisms seems to be of limited value in the investigation of PCVT in south Indian women.

Factor V Leiden as a Common Genetic Risk Factor for Venous Thromboembolism

PURPOSE

To increase nurses' knowledge of the Factor V Leiden (FVL) genetic trait for venous thromboembolism.

ORGANIZING FRAMEWORK

An overview of the history, prevalence, and predisposition of the FVL genetic mutation, including who should be tested and how and in what circumstances people with FVL should be treated.

FINDINGS

FVL is the most commonly recognized genetic trait associated with venous thrombosis. It is found predominantly in Caucasian populations. Biochemically it causes "activated protein C resistance (APCR)." The decision to test for FVL depends on whether the information gained will potentially improve the health care of the person or family. For people who have had deep venous thrombosis, testing for FVL will likely not alter treatment approaches. Currently the advantage for testing is primarily limited to asymptomatic family members who carry FVL and who have had deep vein thrombosis. Close relatives who also carry the mutated gene might benefit from prophylactic anticoagulation when their risk of thrombosis is increased by temporary factors such as surgery.

CONCLUSIONS

Nurses are in a unique position to provide accurate information and counseling when patients and their family members are presented with the results of thrombophilia testing.

Role of the geneticist in testing and counseling for inherited thrombophilia

Within the past decade, the identification of two mutations that are relatively prevalent among the white population (the factor V Leiden and prothrombin G20210A 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). VTE is clearly a multigenic disorder, with well-characterized examples of gene-gene and gene-environment interactions underlying its pathogenesis. Increasing numbers of patients are being referred for testing, and many more diagnoses of inherited thrombophilia are being made. The purpose of this article is to discuss the practical applications of both diagnostic testing and genetic counseling for the major inherited thrombophilias: inherited resistance to activated protein C/factor V Leiden, prothrombin G20210A mutation, protein C deficiency, protein S deficiency, and antithrombin deficiency. A description of each entity is included along with a discussion of the indications for testing, selection of the most appropriate screening test, and proper interpretation of test results. Informed consent for testing, screening of asymptomatic individuals in special circumstances (such as during pregnancy or before initiation of estrogen therapy), screening of family members, and posttest education are also addressed. This article emphasizes that these polymorphisms should be regarded as risk factors for thrombosis whose clinical expression generally depends on the coexistence of additional thrombophilic mutations or environmental conditions that provoke the development of VTE.