Clinical and laboratory management of the prothrombin G20210A mutation

The Association of Prothrombin Gene G20210A Mutation with Recurrent Venous Thromboembolism: Evidence from a Meta-Analysis

OBJECTIVES

The prothrombin (PT) G20210A mutation is one of the most prevalent genetic variations associated with an increased susceptibility to the first episode of venous thromboembolism (VTE). However, it remains uncertain whether this inherited thrombophilic abnormality also poses a risk for recurrent VTE. This meta-analysis aimed to assess the relation of PT G20210A mutation to the risk of recurrent VTE.

METHODS

PubMed and Scopus were systematically searched for pertinent prospective studies. Relative risks (RR) and 95% confidence intervals (CI) were used to test the association. Sixteen studies, with 16,174 participants, were included.

RESULTS

Carriers of the G20210 A mutation were at increased risk of recurrent VTE (RR = 1.60, 95% CI = 1.20-2.14) compared to noncarriers; the increased risk was observed in heterozygotes (GA versus GG) (RR = 1.79, 95% CI = 1.24-2.57), but not in GA/AA mutation.

CONCLUSIONS

This association was found to be significant in the long term (≥5 years of follow-up), but not in the short term (<5 years of follow-up).

Homozygous Carriers of F2 c.20210G>A Variant: A Report of Two Cases and Literature Review

Thromboembolism is known to be a multifactorial event that is impacted by various genetic and environmental factors. The genetics society's recommended name for this variant is c.*97G>A (this is the nomenclature we need to use in the patient report). However, people have been using legacy names c.20210G>A or G20210A (so these are common names). One of the most common genetic variants associated with inherited thrombophilias, F2 c.20210G>A is acknowledged to be a weak but significant risk factor for thromboembolism. However, its clinical presentation has been described as phenotypically heterogeneous. We present two rare cases with homozygous F2 c.20210G>A variant, one of which also carries a heterozygous variant in coagulation factor V gene F5, c.1601G>A (p.Arg534Gln; commonly known as factor V Leiden). We described the clinical courses of these two cases and discussed F2 c.20210G>A and factor V Leiden as genetic risk factors in thromboembolism, the role of provoking factors, such as surgery and malignancy, and the management of such patients.

A Successful Collaborative Approach to the Perioperative Management After Hip Arthroscopy of a Patient with Heterozygous Prothrombin G20210A Mutation: A Case Report

CASE

We report on a patient with heterozygous prothrombin G20210A mutation (PTM) and a history of venous thromboembolism (VTE) after knee arthroscopy, who was undergoing hip arthroscopy. This common mutation has an overall prevalence of 2.0% and results in a 280% to 420% likelihood of thrombosis compared to patients without the mutation.

CONCLUSIONS

Hip arthroscopy is associated with a low risk of VTE with currently no guidelines for thromboprophylaxis. Patients should be managed in relation to their risk factors utilizing a collaborative, individualized approach. Treatment with short-term low-molecular-weight heparin resulted in no thromboembolism at 18-month follow-up for this patient with PTM.

Optimal utilization of thrombophilia testing

The global incidence of venous thromboembolism is high so laboratory testing for hereditary thrombophilia and selected acquired thrombophilia is common. Given the costs associated with testing and multiple pre-analytic and analytic variables affecting the assays, careful patient selection and timing of testing and diligent application to patient management are critical to providing high-value clinical care. Collaboration between the ordering providers and performing laboratories has the potential to achieve these goals. Herein, utility of thrombophilia testing, variables that affect the assays, and impact on patient management are reviewed. Where available, information on cost-effectiveness is discussed.

Epidemiology of venous thromboembolism

Thrombosis can affect any venous circulation. Venous thromboembolism (VTE) includes deep-vein thrombosis of the leg or pelvis, and its complication, pulmonary embolism. VTE is a fairly common disease, particularly in older age, and is associated with reduced survival, substantial health-care costs, and a high rate of recurrence. VTE is a complex (multifactorial) disease, involving interactions between acquired or inherited predispositions to thrombosis and various risk factors. Major risk factors for incident VTE include hospitalization for surgery or acute illness, active cancer, neurological disease with leg paresis, nursing-home confinement, trauma or fracture, superficial vein thrombosis, and-in women-pregnancy and puerperium, oral contraception, and hormone therapy. Although independent risk factors for incident VTE and predictors of VTE recurrence have been identified, and effective primary and secondary prophylaxis is available, the occurrence of VTE seems to be fairly constant, or even increasing.

Hypercoagulable states: an algorithmic approach to laboratory testing and update on monitoring of direct oral anticoagulants

Hypercoagulability can result from a variety of inherited and, more commonly, acquired conditions. Testing for the underlying cause of thrombosis in a patient is complicated both by the number and variety of clinical conditions that can cause hypercoagulability as well as the many potential assay interferences. Using an algorithmic approach to hypercoagulability testing provides the ability to tailor assay selection to the clinical scenario. It also reduces the number of unnecessary tests performed, saving cost and time, and preventing potential false results. New oral anticoagulants are powerful tools for managing hypercoagulable patients; however, their use introduces new challenges in terms of test interpretation and therapeutic monitoring. The coagulation laboratory plays an essential role in testing for and treating hypercoagulable states. The input of laboratory professionals is necessary to guide appropriate testing and synthesize interpretation of results.

Evaluation of chromosomal abnormalities and common trombophilic mutations in cases with recurrent miscarriage

BACKGROUND

Recurrent miscarriage (RM) is a frequent obstetric problem. Its' pathophysiology is poorly understood. Infections, genetic, endocrine, anatomic and immunologic problems have been suggested as causes for RM.

OBJECTIVE

To evaluate the frequency of chromosomal abnormalities and 3 common thrombophilic mutations in couples with RM.

METHODS

A retrospective data collection was performed for the results of the cytogenetic analysis of the couples and Methylenetetrahydrofolate Reductase (MTHFR) C677T, Factor V Leiden (FVL) G1691A and Prothrombin (PTm) G20210A mutations of the mother in 142 couples suffering from RM.

RESULTS

Prevalence of FVL, MTHFR, and PTm gene mutations were similar between cases shaving 2 or ≥3 abortions (P=0.528; P=0.233; P=0.375). In patients with FVL, MTHFR and PTm gene mutations, the OR's of having ≥3 abortions when compared to having 2 abortions were 1.515 (95% CI: 0.414-5.552), 0.573 (95% CI: 0.228-1.441), and 2.848 (95% CI: 0.355-22.871). All cases with PTm mutation had ≥3 abortions and all abortions occurred between 6-8 gestational weeks.

CONCLUSION

Chromosomal abnormalities and thrombophilic mutations (especially PTm) seem to have an important role in RM. Additional larger studies involving investigation of more genes that may have a role in pregnancy are needed to assess this association.

Prothrombin time, activated partial thromboplastin time and dilute Russell's Viper Venom times are not shorter in patients with the prothrombin G20210A mutation, and dilute Russell's Viper Venom time may be longer

INTRODUCTION

Prothrombin G20210A (PT20210) carriers have increased prothrombin levels and increased risk for venous thrombosis. We hypothesized PT20210 carriers would have decreased PT, aPTT, and dRVVT clotting times.

METHODS

We reviewed 1186 thrombotic risk panels that included PT, aPTT, dRVVT, and PT20210 genotype with potential confounding variables, excluding samples consistent with anticoagulant therapy or lupus anticoagulant presence. We examined relationships of PT20210 with PT, aPTT, and dRVVT correcting for covariates using multivariate regression. We confirmed associations in 1876 separate panel results and a group of homozygotes for PT20210 and used general linear models to determine if associated tests predict PT20210 status.

RESULTS

Neither PT, aPTT, nor dRVVT was shorter in PT20210 carriers. Contrary to our hypothesis, PT20210 was significantly associated with higher dRVVT (p=0.001), but not PT or aPTT. dRVVT differences were significant in a replicate sample p=0.035 and an additional sample of PT20210 homozygotes (p=0.02). Of all variables available, only dRVVT predicted PT20210 carrier status (p=0.0008, AUC=0.64).

CONCLUSIONS

We observed an association between longer dRVVT and the prothrombin G20210A mutation in a retrospective observational study. These findings merit further study in large well-characterized clinical cohorts and laboratory research experiments.

Pathology consultation on the laboratory evaluation of thrombophilia: when, how, and why

Venous thromboembolism (VTE) results from the interaction of the Virchow triad (venous stasis, endothelial injury, and hypercoagulability). Risk factors for increased hypercoagulability, or thrombophilia, include activated protein C resistance/factor V Leiden, the prothrombin G20210A mutation, deficiencies of the natural anticoagulants (antithrombin, proteins C and S), antiphospholipid antibodies, hyperhomocysteinemia, and increased factor VIII activity. Not all patients with VTE need to be tested for such risk factors, but patients with thrombophilia should be evaluated for all possibilities to better estimate risk. At the same time, testing should be patient-specific because assay results are affected by preanalytic variables, including thrombosis and anticoagulant therapy.

Replication and characterisation of genetic variants in the fibrinogen gene cluster with plasma fibrinogen levels and haematological traits in the Third National Health and Nutrition Examination Survey

Previous genetic association studies of the fibrinogen gene cluster have identified associations with plasma fibrinogen levels. These studies are typically limited to plasma fibrinogen measured among European-descent populations. We sought to replicate previous well-known associations with fibrinogen variants and plasma fibrinogen. We then sought to identify and characterise novel associations with fibrinogen variants with plasma fibrinogen and several haematological traits in three racial/ethnic populations. We genotyped 25 single nucleotide polymorphisms (SNPs) in the fibrinogen gene cluster in 2,631 non-Hispanic whites, 2,108 non-Hispanic blacks, and 2,073 Mexican-Americans from the Third National Health and Nutrition Examination Survey (NHANES). We performed single SNP tests of association for plasma fibrinogen, mean platelet volume, platelet distribution width, platelet count, white blood cell count, and serum triglycerides. Five previously identified associations with plasma fibrinogen replicated in our study in non-Hispanic whites and blacks. We identified two novel associations between genetic variants and decreased plasma fibrinogen: rs2227395 (p=0.0007; non-Hispanic whites) and rs2070022 (p=0.001; Mexican-Americans). Several fibrinogen SNPs were also associated with haematological traits: rs6050 with decreased platelet distribution width in non-Hispanic whites; rs6050 and rs2066879 with decreased and increased platelet distribution width, respectively, in non-Hispanic whites;rs2227409 with increased mean platelet volume, rs2070017 with decreased platelet count, and rs6063 with increased platelet distribution width in non-Hispanic blacks; and rs4220 and rs2227395 with decreased white blood cell count, rs2227409 with increased platelet distribution width, rs2066860 and rs1800792 with increased and decreased triclyceride levels, respectively, and rs1800792 with decreased platelet counts in Mexican-Americans. We successfully replicated and identified novel associations with fibrinogen variants and plasma fibrinogen. These data confirm the importance of the fibrinogen gene cluster for plasma fibrinogen levels as well as suggest this gene cluster may have pleiotropic effects on haematological traits.

Diagnostic algorithm for thrombophilia screening

Thrombophilia screening is aimed at detecting the most frequent and well-defined causes of venous thrombosis, such as activated protein C resistance/factor V Leiden mutation, prothrombin G20210A gene mutation, deficiencies of natural anticoagulants, such as antithrombin, protein C and protein S, the presence of antiphospholipid antibodies, hyperhomocysteinemia and increased factor VIII activity. At this time, thrombophilia screening is not recommended for those possible congenital or acquired risk factors, whose association with increased risk of thrombosis has not been proven sufficiently. Laboratory investigations should include a step-wise approach to the diagnosis of thrombotic disorders with respect to the assays and methods of analysis that are used. The assays recommended for the first diagnostic step of screening should establish, whether the subject has one of the common causes of thrombophilia. If one or more abnormal results are obtained, the second diagnostic step includes the assays recommended for confirmation and/or characterization of the defect. When performing the investigation of thrombophilia, it is important to consider all pre-analytical and other variables that may affect the results of thrombophilia testing, including time of testing, age, gender, liver function, hormonal status, pregnancy or the acute phase response to inflammatory diseases. This is necessary, in order to avoid, any misinterpretation of the results. This review summarizes the current knowledge concerning thrombophilia investigations, with special focus on the diagnostic algorithm regarding patient selection, the assays and methods of analysis used and all the variables that should be considered when employing tests for the diagnosis of thrombophilia.

Hereditary thrombophilic risk factors for recurrent pregnancy loss

This review summarizes current knowledge about the role of hereditary hypercoagulation factors predisposing to thrombophilia-associated recurrent fetal loss. Thrombophilias are a major cause of adverse pregnancy outcome, playing a role in the etiology of up to 40% of cases worldwide. Hereditary thrombophilic predispositions to recurrent pregnancy wastage include genetic lesions in blood coagulation factors II and V as well as natural anticoagulants antithrombin, protein C, and protein S. Furthermore, methylenetetrahydrofolate reductase gene variants conferring higher thrombophilia risk in combination with these mutations and the newly described annexin A5 gene M2 promoter allele are associated with repeated fetal loss. The review gives a concise description of the molecular defects arising from the genetic changes, of the role these factors play in the timing and definition of fetal loss, and risk estimates from available studies and meta-analysis. This knowledge is instrumental for a more precise assessment of individual risks for repeated fetal loss and should guide therapeutic strategies, where relevant. Since the average childbearing age increases in Western societies, the importance of a timely diagnosis of fetal loss predisposition is increasing.

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.

European External Quality Control Study on the Competence of Laboratories to Recognize Rare Sequence Variants Resulting in Unusual Genotyping Results

Background: Depending on the method used, rare sequence variants adjacent to the single nucleotide polymorphism (SNP) of interest may cause unusual or erroneous genotyping results. Because such rare variants are known for many genes commonly tested in diagnostic laboratories, we organized a proficiency study to assess their influence on the accuracy of reported laboratory results.

Methods: Four external quality control materials were processed and sent to 283 laboratories through 3 EQA organizers for analysis of the prothrombin 20210G&gt;A mutation. Two of these quality control materials contained sequence variants introduced by site-directed mutagenesis.

Results: One hundred eighty-nine laboratories participated in the study. When samples gave a usual result with the method applied, the error rate was 5.1%. Detailed analysis showed that more than 70% of the failures were reported from only 9 laboratories. Allele-specific amplification-based PCR had a much higher error rate than other methods (18.3% vs 2.9%). The variants 20209C&gt;T and [20175T&gt;G; 20179_20180delAC] resulted in unusual genotyping results in 67 and 85 laboratories, respectively. Eighty-three (54.6%) of these unusual results were not recognized, 32 (21.1%) were attributed to technical issues, and only 37 (24.3%) were recognized as another sequence variant.

Conclusions: Our findings revealed that some of the participating laboratories were not able to recognize and correctly interpret unusual genotyping results caused by rare SNPs. Our study indicates that the majority of the failures could be avoided by improved training and careful selection and validation of the methods applied.

Do inherited hypercoagulable states play a role in thrombotic events affecting kidney/pancreas transplant recipients?

BACKGROUND

Pancreas graft thrombosis remains the leading non-immunologic cause of graft loss after pancreas transplantation. We studied the role of hypercoagulable states (HCS) in pancreas graft thrombosis (pthx).

METHODS

Between January 1, 1994, and January 1, 2003, 131 pancreas transplant recipients experienced a pthx (n = 67) or other thrombotic events. Fifty-six recipients consented to have their blood drawn and tested for the HCS. These results were compared with a control group of pancreas transplant recipients who did not experience a thrombotic event. Fisher's exact test was used to compare the groups.

RESULTS

We found 18% of the recipients with pancreas thrombosis to have a HCS. Factor V Leiden (FVL) was found in 15% vs. 4% in the control group (p = ns) vs. 3-5% in the general white population. We found 3% of the pancreas thrombosis patients to have a prothrombin gene mutation (PGM) vs. 0% in the control group (p = ns) vs. 1-2% in the general white population.

CONCLUSIONS

Of pancreas transplant recipients with thrombosis, 18% had one or more of the most common factors associated with a HCS (FVL or PGM). This can be compared with 4% in a control group and 4-7% in the general white population, respectively. Although the differences are not statistically significant due to small numbers, we feel that the findings may be clinically relevant. While this is only a pilot study, it may be reasonable to screen select pancreas transplant candidates for HCS, especially FVL and PGM, until more data become available.

Sickle cell trait and the risk of venous thromboembolism among blacks

People with sickle cell disease have a chronically activated coagulation system and display hemostatic perturbations, but it is unknown whether they experience an increased risk of venous thromboembolism. We conducted a case-control study of venous thromboembolism that included 515 hospitalized black patients and 555 black controls obtained from medical clinics. All subjects were assayed for hemoglobin S and hemoglobin C genotypes. The prevalence of the S allele was 0.070 and 0.032 for case patients and controls, respectively (P < .001). The odds that a patient had sickle cell trait were approximately twice that of a control, indicating that the risk of venous thromboembolism is increased approximately 2-fold among blacks with sickle cell trait compared with those with the wild-type genotype (odds ratio = 1.8 with 95% confidence interval, 1.2-2.9). The odds ratio for pulmonary embolism and sickle cell trait was higher, 3.9 (2.2-6.9). The prevalence of sickle cell disease was also increased among case patients compared with controls. We conclude that sickle cell trait is a risk factor for venous thromboembolism and that the proportion of venous thromboembolism among blacks attributable to the mutation is approximately 7%.

Phenotypic Heterogeneity in Patients with Homozygous Prothrombin 20210AA Genotype. A paper from the 2005 William Beaumont Hospital Symposium on Molecular Pathology

Venous thromboembolic events (VTEs) affect an estimated 1 in 1000 people annually, resulting in approximately 50,000 deaths, with prevalence increasing with age. The genetic contributors to thrombosis have been described and further explored within the last 15 years as molecular diagnostic techniques have become more widely used. The prothrombin G20210A mutation is the second most common inherited thrombotic risk factor after factor V Leiden. Generally present in less than 5% of the population, the mutation's prevalence varies greatly with ethnicity. The G20210A mutation confers a mildly increased thrombotic risk that is compounded by the presence of other risk factors. One striking characteristic of the G20210A mutation is the phenotypic heterogeneity of the rare homozygous cases. Forty percent of the reported homozygous cases are asymptomatic. Many of the symptomatic patients have additional risk factors that might compound the thrombotic risk. We present here a review of the literature for the homozygous prothrombin G20210A mutation and describe additional cases that exemplify the heterogeneous nature of this entity.

Acute Bowel Ischemia Following Spinal Surgery

Acute mesenteric ischemia is a morbid condition that may be difficult to diagnose due to nonspecific nature of its symptoms. To our knowledge, such a complication has not previously been reported after spinal surgery via the posterior approach. We describe the case of a 43-year-old woman who developed acute mesenteric ischemia several days after a surgical procedure for a lumbar spondylolisthesis via the posterior route. This chronic course is suggestive for venous intestinal ischemia. Prone position and hypotension during the procedure may have favored blood stasis and mesenteric vein occlusion in this patient with an inherited hypercoagulable state.

False-negative factor V Leiden genetic testing in a patient with recurrent deep venous thrombosis

False-negative genetic testing of the factor V Leiden (fVL) mutation is unusual. We report a case of a young woman with a history of deep venous thrombosis tested for the fVL at four separate laboratories on four separate dates. Two laboratories reported the patient to be heterozygous for the fVL, while the other two reported no evidence of a mutation. Testing methods of the various laboratories were reviewed, and additional testing was performed on stored and newly drawn DNA samples, including sequencing of the fVL gene segment. The preponderance of evidence indicates the patient to be heterozygous for the fVL mutation. Dissection of data suggests that either sample misidentification or faulty allele specific amplification methods could have led to false-negative results in two laboratories. In one of the two laboratories, misinterpretation of results and clerical error could not be excluded. There is a need for standardization of optimized fVL genetic testing methods. Further education of ordering physicians on the limitations of genetic testing is necessary.

Reference materials (RMs) for analysis of the human factor II (prothrombin) gene G20210A mutation

The Scientific Committee of Molecular Biology Techniques (C-MBT) in Clinical Chemistry of the IFCC has initiated a joint project in co-operation with the European Commission, Joint Research Centre, Institute of Reference Materials and Measurements to develop and produce plasmid-type reference materials (RMs) for the analysis of the human prothrombin gene G20210A mutation. Although DNA tests have a high impact on clinical decision-making and the number of tests performed in diagnostic laboratories is high, issues of quality and quality assurance exist, and currently only a few RMs for clinical genetic testing are available. A gene fragment chosen was produced that spans all primer annealing sites published to date. Both the wild-type and mutant alleles of this gene fragment were cloned into a pUC18 plasmid and two plasmid RMs were produced. In addition, a mixture of both plasmids was produced to mimic the heterozygous genotype. The present study describes the performance of these reference materials in a commutability study, in which they were tested by nine different methods in 13 expert laboratories. This series of plasmid RMs are, to the best of our knowledge, the first plasmid-type clinical genetic RMs introduced worldwide.

Prothrombin G20210A mutation in cases with recurrent miscarriage: a study of the mediterranean population

BACKGROUND

Thrombophilic predisposition may be one of the underlying causes of recurrent miscariage (RM). The purpose of this study was to evaluate the Prothrombin G20210A mutation in cases with history of RM.

MATERIAL AND METHODS

A total of 104 cases, 55 with diagnosis of RM and 49 control cases, were included in this controlled study. In all cases, in addition to full examination tests, Prothrombin 20210A mutation analysis was carried out by means of Polymerase Chain Reaction (PCR).

RESULTS

Mean number of the abortion was 3.51 +/- 0.74 in the RM group and 0.08 +/- 0.27 in the control group (p < 0.05). As a consequence of comprehensive examinations, in 24 (43.6%) of 55 RM cases at least one etiologic factor was put forth. Prothrombin G20210A mutation was observed in six (10.9%) cases of the RM group and one (2.04%) in the control group (p < 0.05). Four of the six cases (66.7%) of Prothrombin G20210A mutation had a subsequent pregnancy. Among these four pregnancies, there was one spontaneous loss at 14 weeks of gestation and one severe pre-eclampsia.

CONCLUSION

Our data together with literature suggest that Prothrombin G20210A mutation may be associated with RM. We recommend this genetic testing as a screening tool for women with history of RM.

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.

Extensive Aortic Thromboembolism Due to Acquired Hypercoagulable State: An Autopsy Case Report

Aortic thrombosis rarely occurs without severe atherosclerosis, aneurysm, or cardiosurgical or traumatic state. Arterial thrombosis is commonly related to an inherited and/or acquired hypercoagulable state. A 50-year-old woman presented with diffuse abdominal pain. One day after her admission, she experienced bloody stools. Computed tomography showed multiple extensive thromboses in the aorta and superior mesentery arteries. She underwent a partial jejunoileostomy and colectomy for extensive bowel infarction. Following surgery, her condition deteriorated and she died on the fourth hospital day. At autopsy, gross examination showed 2 large thrombi (7 and 8 cm in length) in the proximal and descending (thoracic) aorta, with mild atherosclerosis. A mesenteric artery thromboembolus with extensive bowel infarction was present. Postmortem laboratory studies revealed an elevated anticardiolipin immunoglobulin G antibody level. The thrombotic state in this patient was considered multifactorial secondary to acquired risk factors, including obesity, mild aortic atherosclerosis with coronary artery disease, and presence of a high titer anticardiolipin antibody.

Risk factors and clinical presentation of portal vein thrombosis in patients with liver cirrhosis

BACKGROUND/AIMS

Portal vein thrombosis in patients with liver cirrhosis is usually associated to hepatocellular carcinoma. Clinical presentation of non-neoplastic portal vein thrombosis (PVT) in cirrhotic patients has not been specifically studied and risk factors of PVT in this group of patients are still poorly understood.

METHODS

We studied all patients with PVT and liver cirrhosis admitted to our Unit from January 1998 to December 2002. They were paired (by gender, age and Child-Pugh score) to a group of cirrhotic patients without PVT and screened for acquired and inherited thrombophilic risk factors. These factors together with the site of thrombosis and the severity of the liver disease were correlated to the clinical presentation of PVT.

RESULTS

Out of a total of 701 cirrhotic patients admitted to our hospital and routinely screened with Doppler ultrasound, 79 (11.2%) were found to have PVT. Of these, 34 (43%) were asymptomatic and 45 (57%) were symptomatic (31 presented with portal hypertensive bleed and 14 with abdominal pain, 10 of whom had intestinal infarction). Mesenteric vein involvement was never asymptomatic and lead to intestinal ischemia or infarction. Most patients were in class Child-Pugh B and C. Among thrombophilic risk factors studied only the mutation 20210 of the prothrombin gene resulted independently associated to PVT.

CONCLUSIONS

Portal vein thrombosis may be completely asymptomatic in patients with liver cirrhosis; however in more than half of cases presents with life-threatening complications such as gastrointestinal haemorrhage and intestinal infarction. Cirrhotic patients with PVT usually have an advanced liver disease and the presence of the mutation 20210 of the prothrombin gene increases more than fivefold the risk of PVT.

Inherited and acquired thrombophilias and poor pregnancy outcome: should we be treating with heparin?

PURPOSE OF REVIEW

The most important acquired thrombophilia related to poor pregnancy outcome is probably antiphospholipid syndrome. Inherited thrombophilias that have been implicated in venous thromboembolism and poor pregnancy outcome and for which standard tests are generally available are antithrombin III deficiency, the factor V Leiden mutation, prothrombin G20210A mutation and the C677T polymorphism in the methylenetetrahydrofolate reductase system implicated in mild hyperhomocysteinaemia. The management of antiphospholipid syndrome with previous fetal losses is well documented and substantiated by small clinical trials. It is the purpose of this review to investigate new contributions to this field since June 2002.

RECENT FINDINGS

Only one randomized trial was published during the review period, but a Cochrane review and several excellent review articles appeared detailing management.

SUMMARY

There is a dire lack of randomized trials in the literature on the efficacy of heparin or other coagulation modulators on pregnancy outcome in patients with inherited thrombophilias. There is consensus on thrombo-prophylaxis for antiphospholipid syndrome. Protocols for the management of venous thromboembolism and pulmonary emboli related to pregnancy are well established.

Elevated hemostatic factor levels as potential risk factors for thrombosis

OBJECTIVES

To review the state of the art relating to elevated hemostatic factor levels as a potential risk factor for thrombosis, as reflected by the medical literature and the consensus opinion of recognized experts in the field, and to make recommendations for the use of specific measurements of hemostatic factor levels in the assessment of thrombotic risk in individual patients.

DATA SOURCES

Review of the medical literature, primarily from the last 10 years.

DATA EXTRACTION AND SYNTHESIS

After an initial assessment of the literature, key points were identified. Experts were assigned to do an in-depth review of the literature and to prepare a summary of their findings and recommendations. A draft manuscript was prepared and circulated to every participant in the College of American Pathologists Conference XXXVI: Diagnostic Issues in Thrombophilia prior to the conference. Each of the key points and associated recommendations was then presented for discussion at the conference. Recommendations were accepted if a consensus of the 27 experts attending the conference was reached. The results of the discussion were used to revise the manuscript into its final form.

CONCLUSIONS

Consensus was reached on 8 recommendations concerning the use of hemostatic factor levels in the assessment of thrombotic risk in individual patients. Detailed discussion of the rationale for each of these recommendations is presented in the article. This is an evolving area of research. While routine use of factor level measurements is not recommended, improvements in assay methodology and further clinical studies may change these recommendations in the future.

College of American Pathologists Consensus Conference XXXVI: Diagnostic Issues in Thrombophilia

OBJECTIVES

To review the state of the art relating to laboratory testing for thrombophilia, as reflected by the medical literature and the consensus opinion of recognized experts in the field, and to make recommendations regarding laboratory testing (whom to test, when to test, what tests to perform, rationale for testing, and other issues) in the assessment of thrombotic risk in individual patients and their family members.

DATA SOURCES

Review of the medical literature (primarily from the last 10 years) and the experience and opinions of experts in the field were used as data sources.

DATA EXTRACTION AND SYNTHESIS

Participating authors evaluated the medical literature and prepared manuscripts with specific proposed recommendations. Drafts of all of the manuscripts were prepared and circulated to every participant in the College of American Pathologists Conference XXXVI: Diagnostic Issues in Thrombophilia prior to the conference. Each of the conclusions and associated recommendations was then presented for discussion. Recommendations were accepted if a consensus of 70% or more of the 27 experts attending the conference was reached. The results of the discussion were then used to revise the manuscripts and recommendations into final form.

CONCLUSIONS

Consensus was reached on 179 recommendations, all of which are presented in articles in this issue of the Archives. Detailed discussion of the rationale for each of these recommendations is found in the text of the respective articles, along with citations to justify the level of evidence for the recommendations. This is an evolving area of research, and it is certain that further clinical studies will change many of the recommendations, cause some to be deleted, and add others in the future.