Prothrombin 20210G>A is an ancestral prothrombotic mutation that occurred in whites approximately 24 000 years ago

The anticoagulant function of coagulation factor V

Almost two decades ago an anticoagulant function of factor V (FV) was discovered, as an anticoagulant cofactor for activated protein C (APC). A natural mutant of FV in which the R506 inactivation site was mutated to Gln (FVLeiden) was inactivated slower by APC, but also could not function as anticoagulant cofactor for APC in the inactivation of activated factor VIII (FVIIIa). This mutation is prevalent in populations of Caucasian descent, and increases the chance of thrombotic events in carriers. Characterisation of the FV anticoagulant effect has elucidated multiple properties of the anticoagulant function of FV: 1) Cleavage of FV at position 506 by APC is required for anticoagulant function. 2) The C-terminal part of the FV B domain is required and the B domain must have an intact connection with the A3 domain of FV. 3) FV must be bound to a negatively charged phospholipid membrane. 4) Protein S also needs to be present. 5) FV acts as a cofactor for inactivation of both FVa and FVIIIa. 6) The prothrombotic function of FVLeiden is a function of both reduced APC cofactor activity and resistance of FVa to APC inactivation. However, detailed structural and mechanistic properties remain to be further explored.

Factor V Leiden

Factor V Leiden (FVLeiden ) is a common hereditary thrombophilia that causes activated protein C (APC) resistance. This review describes many of the most fascinating features of FVLeiden , including background features, mechanisms of hypercoagulability, the founder mutation concept, the "FVLeiden paradox," synergistic interaction with other thrombotic risk factors, the intertwined relationship between FVLeiden and APC resistance testing, and other, uncommon mutations implicated in causing APC resistance. In addition, there are several conditions where laboratory tests for APC resistance and FVLeiden are or can be discrepant, including lupus anticoagulants, anticoagulants such as direct thrombin inhibitors (dabigatran, argatroban, and bivalirudin) and rivaroxaban, as well as pseudohomozygous, pseudo-wildtype, liver transplant, and bone marrow transplant patients. The laboratory test error rate for FVLeiden is also presented.

Ethnic diversity in the genetics of venous thromboembolism

Genetic susceptibility is considered as a crucial factor for the development of venous thromboembolism (VTE). Epidemiologic and genetic studies have revealed clear disparities in the incidence of VTE and the distribution of genetic factors for VTE in populations stratified by ethnicity worldwide. While gain-of-function polymorphisms in the procoagulant genes are common inherited factors in European-origin populations, the most prevalent molecular basis for venous thrombosis in Asians is confirmed to be dysfunctional variants in the anticoagulant genes. With the breakthrough of genomic technologies, a set of novel common alleles and rare mutations associated with VTE have also been identified, in different ethnic groups. Several putative pathways contributing to the pathogenesis of thrombophilia in populations of African-ancestry are largely unknown, as current knowledge of hereditary and acquired risk factors do not fully explain the highest risk of VTE in Black groups. In-depth studies across diverse ethnic populations are needed to unravel the whole genetics of VTE, which will help developing individual risk prediction models and strategies to minimise VTE in all populations.

Activated protein C resistance testing for factor V Leiden

Activated protein C resistance assays can detect factor V Leiden with high accuracy, depending on the method used. Factor Xa inhibitors such as rivaroxaban and direct thrombin inhibitors including dabigatran, argatroban, and bivalirudin can cause falsely normal results. Lupus anticoagulants can cause incorrect results in most current assays. Assays that include dilution into factor V-deficient plasma are needed to avoid interference from factor deficiencies or elevations, which can arise from a wide variety of conditions such as warfarin, liver dysfunction, or pregnancy. The pros and cons of the currently available assays are discussed.

MUTYH-associated polyposis (MAP): evidence for the origin of the common European mutations p.Tyr179Cys and p.Gly396Asp by founder events

MUTYH-associated polyposis (MAP) is an autosomal recessive adenomatous polyposis caused by biallelic germline mutations of the base-excision-repair gene MUTYH. In MAP patients of European origin, the combined allele frequency of the mutations p.Tyr179Cys and p.Gly396Asp ranges between 50 and 82%, while these mutations have not been identified in Far Eastern Asian populations, supporting the hypothesis that a founder effect has occurred at some point in European history. To investigate the natural history of the two common European MUTYH alleles, we genotyped six gene-flanking microsatellite markers in 80 unrelated Italian and German MAP patients segregating one or both mutations and calculated their age in generations (g) by using DMLE+2.2 software. Three distinct common haplotypes, one for p.Tyr179Cys and two for p.Gly396Asp, were identified. Estimated mutation ages were 305 g (95% CS: 271-418) for p.Tyr179Cys and 350 g (95% CS: 313-435) for p.Gly396Asp. These results provide evidence for strong founder effects and suggest that the p.Tyr179Cys and p.Gly396Asp mutations derive from ancestors who lived between 5-8 thousand years and 6-9 thousand years B.C., respectively.

Origin of Swedish hemophilia A mutations

BACKGROUND

Hemophilia A (HA) has a high level of variation within the disease class, with more than 1000 mutations being listed in the HAMSTeRS database. At the same time a number of F8 mutations are present in specific populations at high frequencies.

OBJECTIVES

The simultaneous presence of large numbers of rare mutations and a small number of high-frequency mutations raises questions about the origins of HA mutations. The present study was aimed at describing the origins of HA mutations in the complete Swedish population. The primary issue was to determine what proportion of identical mutations are identical by descent (IBD) and what proportion are attributable to recurrent mutation events. The age of IBD mutations was also determined.

PATIENTS/METHODS

In Sweden, the care of HA is centralized, and the Swedish HA population consists of ~ 750 patients from > 300 families (35% severe, 15% moderate, and 50% mild). Identical haplotypes were defined by single-nucleotide polymorphism and microsatellite haplotyping, and the ages of the mutations were estimated with estiage.

RESULTS

Among 212 presumably unrelated patients with substitution mutations, 97 (46%) had mutations in common with other patients. Haplotyping of the 97 patients showed that 47 had IBD mutations (22%) with estimated ages of between two and 35 generations. The frequency of mild disease increased with an increasing number of patients sharing the mutations.

CONCLUSIONS

A majority of the IBD mutations are mild and have age estimates of a few hundred years, but some could date back to the Middle Ages.

Framing postpartum hemorrhage as a consequence of human placental biology: an evolutionary and comparative perspective

Postpartum hemorrhage (PPH), the leading cause of maternal mortality worldwide, is responsible for 35 percent of maternal deaths. Proximately, PPH results from the failure of the placenta to separate from the uterine wall properly, most often because of impairment of uterine muscle contraction. Despite its prevalence and its well-described clinical manifestations, the ultimate causes of PPH are not known and have not been investigated through an evolutionary lens. We argue that vulnerability to PPH stems from the intensely invasive nature of human placentation. The human placenta causes uterine vessels to undergo transformation to provide the developing fetus with a high plane of maternal resources; the degree of this transformation in humans is extensive. We argue that the particularly invasive nature of the human placenta increases the possibility of increased blood loss at parturition. We review evidence suggesting PPH and other placental disorders represent an evolutionarily novel condition in hominins.

Factor V Leiden mutation and its impact on pregnancy complications

OBJECTIVE

The aim of this prospective study was to find the association between the factor V Leiden mutation and adverse pregnancy outcomes.

METHODS

This study is an analysis of a prospective observational study of the frequency of placenta-mediated complications of factor V Leiden mutation carriers. We compared pregnancy outcomes of 11 women with a heterozygous form of the factor V Leiden mutation with 41 women of a control group.

RESULTS

All pregnancies ended with delivery of a living infant. None of the 52 pregnancies were complicated by venous thromboembolism. There were a few significant differences regarding placenta-mediated complications. The gestational age at delivery showed small significant differences. There was a significant difference in the birth weight deviation in percentage between FVL carriers and controls. The incidence of blood loss exceeding 1000 ml was higher in the control group.

CONCLUSIONS

Carriership of the factor V Leiden mutation did not affect the incidence of preeclampsia. Adverse pregnancy outcomes such as placental abruption were rare. Eclampsia, intrauterine fetal death and venous thromboembolism did not occur. Our results provide evidence that the maternal heterozygous FVL mutation did not increase the risk of an adverse pregnancy outcome.

[Activated protein C resistance and factor V Leiden: clinical interest]

Activated protein C resistance (APCR) is a coagulation abnormality often linked to FV Leiden mutation, a single nucleotide G1691A substitution resulting in arginine 506→glutamine missense factor V mutation. FV Leiden has a frequency of 20 to 30% in groups of patients with venous thrombosis while it is of 4 to 10% in normal subjects. FV Leiden is considered as a weak risk factor of thrombosis except in homozygote. FV Leiden is implicated in deep venous thrombosis occurrence. Duration of oral anticoagulant treatment is six months in patients developing a first venous thrombosis except in patients with combined defects or a clinical context suggesting a high risk of severe relapse. Detection of APCR by coagulation methods is often used in first intention with a high specificity if plasmas tested are diluted in factor V deficient plasma. Genotyping study is essential to establish the heterozygote or homozygote statute and certain teams perform it directly. Nevertheless, APCR not related to FV Leiden could be an independent thrombosis risk factor. APCR and FV Leiden are included in laboratory investigations of thrombophilic markers in patients less than 50 years with venous thrombosis. In arterial thrombosis, FV Leiden implication is weak or absent. FV Leiden increases the risk of thrombosis in other situations as in patients with cancer. An association with recurrent miscarriages and other vasculoplacental complications is also reported in many studies but the data concerning the efficacy of antithrombotic treatment to prevent recurrence are currently insufficient.

Detection of Factor V Leiden and prothrombin c.20210G>A allele by Roche Diagnostics LightCycler®

Venous thrombosis affects one in one thousand people each year, and in many countries, it is a major cause of morbidity and death in hospitalised patients. Factor V Leiden and the prothrombin c.20210G>A transition are relatively common in the Western World, and both increase the risk of venous thrombosis. The author describes the detection of t+++hese two genetic variants on the carousel-based Roche LightCycler®. This simple method has high sensitivity for DNA, making it possible to test blood samples without the need for traditional DNA extraction and purification.

The relationship between blood groups and disease

The relative contribution of founder effects and natural selection to the observed distribution of human blood groups has been debated since blood group frequencies were shown to differ between populations almost a century ago. Advances in our understanding of the migration patterns of early humans from Africa to populate the rest of the world obtained through the use of Y chromosome and mtDNA markers do much to inform this debate. There are clear examples of protection against infectious diseases from inheritance of polymorphisms in genes encoding and regulating the expression of ABH and Lewis antigens in bodily secretions particularly in respect of Helicobacter pylori, norovirus, and cholera infections. However, available evidence suggests surviving malaria is the most significant selective force affecting the expression of blood groups. Red cells lacking or having altered forms of blood group-active molecules are commonly found in regions of the world in which malaria is endemic, notably the Fy(a-b-) phenotype and the S-s- phenotype in Africa and the Ge- and SAO phenotypes in South East Asia. Founder effects provide a more convincing explanation for the distribution of the D- phenotype and the occurrence of hemolytic disease of the fetus and newborn in Europe and Central Asia.

Pesquisa de marcadores de trombofilia em eventos trombóticos arteriais e venosos: registro de 6 anos de investigação

CONTEXTO: Os autores apresentam uma análise epidemiológica sobre a investigação de marcadores de trombofilia em pacientes que apresentaram eventos trombóticos arteriais e/ou venosos acompanhados no Departamento de Angiologia e de Cirurgia Vascular do CENTERVASC no período de janeiro de 2001 a janeiro de 2007. OBJETIVO: Avaliar a prevalência de marcadores de trombofilias congênitas ou adquiridas nos eventos trombóticos venosos e/ou arteriais. MÉTODOS: Entre janeiro de 2001 e janeiro de 2007, 224 pacientes com eventos trombóticos venosos e/ou arteriais foram submetidos a uma rotina de investigação quanto à presença ou não de marcadores de trombofilia, independentemente da idade e história familiar dos pacientes, topografia do evento e presença ou ausência de fatores trombogênicos extrínsecos. RESULTADOS: Foram detectados marcadores de trombofilia em 112 pacientes (50% dos casos). Nestes, observou-se de modo predominante a positividade para anticorpos antifosfolipídios, anticardiolipina e/ou anticoagulante lúpico (39 casos), bem como a presença do fator V de Leiden (43 casos). O sistema venoso foi significativamente o mais acometido, e a ocorrência associada com condições trombogênicas extrínsecas esteve presente em 56 (50%) dos portadores de marcadores de trombofilias. CONCLUSÕES: A presença de marcadores de trombofilia nos pacientes com eventos trombóticos, venosos e/ou arteriais, independentemente da faixa etária ou da existência de fatores extrínsecos associados, foi significativa.

Factor V Leiden in an Urartian, Dating Back to 1000 BC

Factor V Leiden (FVL) is the most common monogenic disorder that causes activated protein C (APC) resistance, creating hyper-coagulation. The mutation shows an uneven geographic distribution, significantly high in European populations. The mutation is believed to have originated approximately 20 000 years ago probably from a geographic region close to Anatolia. This fact makes it noteworthy to search for the mutation in ancient populations that once lived in this area. One of these civilizations, Urartu was centered around Van Lake in Eastern Turkey. The archeological remains from the excavations of the region are dated back to 1000 BC. Teeth, taken from the excavations of Van Yoncatepe fortress, were taken into DNA analysis considering all the precautions for ancient DNA analysis. Multiplex STR (Short Tandem Repeats) analysis were performed both to determine the gender of the samples and to conclude that the samples are preserved from modern DNA contamination. After getting an 80% amplification success for amelogenin, a melting curve analysis using lightcycler was performed to determine the FVL genotype of each sample. Of the 60 samples, 1 gave a positive amplification result for FV gene and was found to be heterozygous. To date, the age of this mutation was estimated based on statistical calculations using haplotype frequencies; here for the first time, we report FVL in an ancient population of 3000 years.

A likelihood model that accounts for censoring due to fetal loss can accurately test the effects of maternal and fetal genotype on the probability of miscarriage

OBJECTIVE

Heritable maternal and fetal thrombophilia and/or hypofibrinolysis are important causes of miscarriage. Under the constraint that fetal genotype is observed only after a live birth, estimating risk is complicated. Censoring prevents use of published statistical methodology. We propose techniques to determine whether increases in miscarriage are due to the fetal genotype, maternal genotype, or both.

METHODS

We propose a study to estimate the risk of miscarriage contributed by an allele, expressed in either dominant or recessive fashion. Using a multinomial likelihood, we derive maximum likelihood estimates of risk for different genotype groups. We describe likelihood ratio tests and a planned hypothesis testing strategy.

RESULTS

Parameter estimation is accurate (bias <0.0011, root mean squared error <0.0780, n = 500). We used simulation to estimate power for studies of three gene mutations: the 4G hypofibrinolytic mutation in the plasminogen activator inhibitor gene (PAI-1), the prothrombin G20210A mutation, and the Factor V Leiden mutation. With 500 families, our methods have approximately 90% power to detect an increase in the miscarriage rate of 0.2, above a background rate of 0.2.

CONCLUSION

Our statistical method can determine whether increases in miscarriage are due to fetal genotype, maternal genotype, or both despite censoring.

The first homozygous family for prothrombin G20210A polymorphism reported in Latin America

The 20210A allele of the prothrombin gene is associated with increased risk of venous thromboembolism. In this study, we described manifestations of thrombosis in four generations of a Colombian family, with four 20210A homozygous carriers and six 20210G/A heterozygous carriers for polymorphism as well as unrelated participants from the same population. The levels of prothrombin in the 20210A homozygote patients were higher than in the normal 20210G homozygotes (133 + 11% and 92.3 + 12.4%, respectively, P < .01) and the 20210G/A heterozygotes (133 + 11% vs. 114.8 + 24%, P < .05). About 2 out of 4 20210A homozygotes and 5 out of 6 20210G/A heterozygous members of this family did not have venous thromboembolism or any other thrombotic manifestation even though one of them had been exposed to thrombotic risk factors. Thus, we posit the effect of 20210A on the thrombotic phenotype in this family seems to be weak.

Advances in understanding pathogenic mechanisms of thrombophilic disorders

Venous thromboembolism is a major medical problem, annually affecting 1 in 1000 individuals. It is a typical multifactorial disease, involving both genetic and circumstantial risk factors that affect a delicate balance between procoagulant and anticoagulant forces. In the last 50 years, the molecular basis of blood coagulation and the anticoagulant systems that control it have been elucidated. This has laid the foundation for discoveries of both common and rare genetic traits that tip the natural balance in favor of coagulation, with a resulting lifelong increased risk of venous thrombosis. Multiple mutations in the genes for anticoagulant proteins such as antithrombin, protein C, and protein S have been identified and constitute important risk factors. Two single mutations in the genes for coagulation factor V (FV Leiden) and prothrombin (20210G>A), resulting from approximately 20,000-year-old mutations with subsequent founder effects, are common in the general population and constitute major genetic risk factors for thrombosis. In celebration of the 50-year anniversary of the American Society of Hematology, this invited review highlights discoveries that have contributed to our present understanding of the systems that control blood coagulation and the genetic factors that are involved in the pathogenesis of venous thrombosis.

Thrombophilic polymorphisms in Israel

Three thrombophilic polymorphisms, FV G1691A, FII G20210A and MTHFR C677T were investigated in Israeli populations by FRET, (fluorescence resonance energy transfer) real-time PCR. We observe extensive variability in the frequencies of each of the polymorphisms, as has been observed in the study of other polymorphisms in these populations. Very high allele frequencies for FV G1691A (the highest 0.087 in Turkish and Greek Jews) and FII G20210A (the highest 0.061 in Georgian Jews) in some of the Israeli populations justify a clinical investigation to assess their risk for venous thrombosis. Principal Coordinates Analysis demonstrates that the Jewish populations are interspersed among the non-Jewish populations. The resemblance of some Jewish populations to certain non-Jewish populations coincides with findings based on classical markers.

The hemostatic balance revisited through the lessons of mankind evolution

Under physiologic conditions, a hemostatic balance is achieved through the effects of natural procoagulant and anticoagulant factors which, in equilibrium with each other, provide hemostasis at the sites of vascular injury. Abnormalities of these hemostasis factors can result in a tendency toward hemorrhagic or thrombotic events. In this review the influence of inherited prothrombotic risk factors--especially the more frequent factor V Leiden and prothrombin gene mutations--on normal and abnormal hemostasis is analyzed from an evolutionary point of view. The effect of inherited bleeding disorders on the development of thrombotic or atherosclerotic processes is also discussed.

Plantar vein thrombosis: a rare cause of plantar foot pain

Plantar vein thrombosis is a rare condition, with only a handful of cases reported in the literature. The cause is unknown; however, the disease has been attributed to prior surgery, trauma, and paraneoplastic conditions. We present a case of a 32-year-old female runner with plantar vein thrombosis diagnosed on contrast-enhanced MRI and confirmed on ultrasound. The symptoms resolved with conservative treatment and evaluation revealed the presence of a prothrombin gene mutation and use of oral contraceptive pills. To our knowledge, this is the first case of plantar vein thrombosis diagnosed initially by MRI. Moreover, this case suggests that plantar vein thrombosis should be considered in patients with hypercoagulable states and plantar foot pain.

Age estimates of ancestral mutations causing factor VII deficiency and Dubin–Johnson syndrome in Iranian and Moroccan Jews are consistent with ancient Jewish migrations

Factor VII (FVII) deficiency and Dubin-Johnson syndrome (DJS) are rare autosomal recessive disorders caused by mutations in F7 and MRP2 genes, respectively. Both disorders are relatively frequent among Iranian and Moroccan Jews. FVII deficiency in both populations is caused by a founder A244V mutation in the F7 gene and DJS is caused by two founder mutations, I1173F and R1150H in the MRP2 gene that are specific for Iranian and Moroccan Jewish patients, respectively. We estimated the age of FVII A244V and MRP2 I1173F by analysis of microsatellite markers flanking F7 and MRP2 genes, respectively, in 13 Iranian Jewish homozygotes for the I1173F mutation and 21 Iranian and Moroccan Jewish homozygotes for the A244V mutation. Dating of the mutations was estimated by the DMLE+2.0 program employing observed linkage disequilibria of multiple genetic markers. The estimated age of the I1173F mutation was approximately 1500 years, and the age of the A244V mutation was approximately 2600 years. These estimates suggest that I1173F causing DJS in Iranian Jews occurred after the separation of Iranian Jews from Moroccan Jews 2000-2600 years ago, while A244V causing FVII deficiency in Iranian and Moroccan Jews occurred prior to the divergence of these two populations.