American College of Medical Genetics consensus statement on factor V Leiden mutation testing

Laboratory Diagnosis of Activated Protein C Resistance and Factor V Leiden

The factor V Leiden (FVL) polymorphism is known as the most common inherited risk factor for venous thrombosis. In turn, FVL is the leading cause of an activated protein C resistance (APCR) phenotype, in which the addition of exogenous activated protein C to plasma does not result in the expected anticoagulant effect. In the routine laboratory approach to the formal diagnosis of FVL, an initial positive screening plasma-based method for APCR is often performed, and only if needed, this is followed by a confirmatory DNA-based assay for FVL. Multiple methods with accepted sensitivity and specificity for determining an APCR/FVL phenotype are commonly categorized into two separate groups: (1) screening plasma-based assays, including qualitative functional clot-based assays, for APCR, and (2) confirmatory DNA-based molecular assays, entailing several tests and platforms, including polymerase chain reaction-based and non-PCR-based techniques, for FVL. This review will describe the methodological aspects of each laboratory test and prepare suggestions on the indication of APCR and FVL testing and method selection.

Inherited thrombophilia transpires with severe coronary arterial thrombosis in wide range of age backgrounds: A report of 3 cases

Introduction

and importance: Protein C and S deficiency are some of the coagulation cascade disorders which may also contributes not only to venous thromboembolism (VTE), but also rarely to arterial thrombosis. Here we present a report of 3 severe coronary artery disease (CAD) cases ranging from very young to elderly patients with concomitant inherited thrombophilia.

Case presentation

The first case was a chronic coronary syndrome from a very young male patient with history of VTE without any other risk factor of CAD. The second case was about premature CAD with triple chronic total occlusion (RCA, LCX, LAD) in patient under 45 years old, with single risk factor. The third case was about accelerated atherosclerosis progression from previously non significant stenosis in RCA into total occlusion in RCA and inferior STEMI in old patient on supposely adequate double anti platelet agent.

Clinical discussion

All patients had protein C and/or S deficiency and first degree family history of VTE, therefore inherited thrombophilia was diagnosed. We gave them oral anticoagulant in addition to their standard treatment for secondary prevention with good outcome and without further adverse event.

Conclusion

It is important to raise awareness to perform screening inherited thrombophilia as an important risk factor for CAD in special subgroup such as young age patient with rapid course progression and family history of VTE. The use of oral anticoagulants as either prophylactic or therapeutic purpose in patients with inherited thrombophilia are safe and effective. However, further research is still needed.

•

Inherited thrombophilia is a rare disease that can causes coronary arterial thrombosis.

•

Inherited thrombophilia screening should be done in special subgroup of patients.

•

There is no treatment guideline for CAD patients with inherited thrombophilia.

Guidelines for genetic testing of healthy adults who deposit samples and related data in bioresource collections and biobanks

Currently, a significant part of research in the fields of human and medical genetics is carried out using tissue samples, genealogical, population, medical and personal data. Their use is of particular relevance in the “genome era”, since only joint analysis of genomic data and health status of the population is crucial for understanding how genes are associated with health and disease. Genetic studies of adults without symptoms of diseases are carried out to obtain data on a possible predisposition to multifactorial diseases, to establish the carrier status of autosomal recessive mutations as part of preconception care and to assess individual sensitivity to drugs. In addition, healthy individuals can be tested to detect an inherited disease at presymptomatic stage. This situation increasingly emphasizes the importance of storing data on genome sequencing or any other patient tests for subsequent data reanalysis, as well as their safety, including biosamples from an individual and one’s family. The review article, based on international experience, summarizes guidelines for genetic testing of healthy individuals. The options for storing biological samples and related data are considered.

Unusual pattern of thrombotic events in young adult non-critically ill patients with COVID-19 may result from an undiagnosed inherited and acquired form of thrombophilia

In 145 previously healthy non-critically ill young adults, coronavirus disease 2019 (COVID-19)-related symptoms, risk factors for thrombosis, coagulation and inflammatory parameters were compared, with 29 patients reporting unusual thrombotic events (UTEs) and 116 not having thrombotic events. The inflammatory indices, coagulation and prothrombotic platelet phenotype (PTPP) were significantly higher in patients with UTEs versus those without. Patients with UTEs were categorised according to detection of thrombophilic genes (TGs), coagulation and inflammatory markers to the non-TG and TG subcohort. A total of 38 UTEs were identified, which included splanchnic vein thrombosis (SVT; 11), stroke (six), cerebral vein thrombosis (five), thrombotic microangiopathy (four), limb ischaemia and inferior vena cava thrombosis (three each), ST-segment elevation myocardial infarction (two), superior vena cava thrombosis (two), upper limb deep venous thrombosis and retinal vein thrombosis, one each. We found a 55% prevalence of TGs mainly heterozygous coagulation factor II, thrombin (FII)-G20210A, Janus kinase 2 (JAK2)-V617F, protein-S, and antithrombin III deficiency with a high (76·9%) prevalence of venous UTEs, multiple vessels thrombosis, and recurrence rate among the TG versus non-TG subcohort. The presence of JAK2-V617F, and FII-G20210A mutations was linked with SVT. Thrombosis in the non-TG subcohort was associated with more haemorrhagic problems, thrombosis progression and a significantly higher level of inflammatory markers, PTPP, mean platelet volume, von Willebrand factor, and factor VIII, which remained high for up to 6 months, as well as elevated D-dimer. Acquired and inherited thrombophilia with endotheliopathy appeared to be a relevant mechanism to explain the occurrence of UTEs that are not correlated to COVID-19 severity.

The prevalence of Factor V Leiden (Arg506Gln) mutation in King Khalid University Hospital patients, 2017-2019

Arg506Gln mutation is responsible for one of the procoagulant factors and most common inherited thrombophilia in the Factor V Leiden (FVL) family. The replacement of the missense mutation for Arg506Gln / R506Q is at 1691st position from Guanine to Adenine with the modification of the amino acid from arginine to glutamine. The aim of this study was to investigate the current prevalence of the G1691A mutation in the FVL gene in the capital city’s King Khalid University Hospitals (KKUH). Since 2017–2019 we have recruited 482 patients in these cross-sectional studies to test the G1691A mutation in KKUH’s FVL gene. DNA was extracted using 2mL of the EDTA blood and genotyping was performed with polymerase chain reaction and the data was analyzed using Sanger sequencing. In this study, 4.4% of the G1691A mutation was found to be positive (combined heterozygous-GA and homozygous-AA variants) and 95.6% of them with negative, i.e., homozygous normal-GG genotypes. Our study concludes that with the advances in genetic testing and their recent availability, early mutation detection could approve the genotype risks for many patients and this mutation is not as rare as previously believed in the Saudi region as our study has established with a 4.4 percent prevalence.

Thrombophilic alterations, migraine, and vascular disease: results from a case-control study

BACKGROUND

The association between thrombophilic alterations, migraine, and vascular events has been broadly investigated but not been completely clarified.

METHODS

In this cross-sectional, case-control study, we included consecutive outpatients diagnosed with migraine referring to a tertiary headache center. Migraine patients were matched to headache-free control subjects. All participants were evaluated for free protein S anticoagulant, functional protein C anticoagulant, homocysteine, and antiphospholipid antibodies (aPLs). History of ischemic stroke (IS) or transient ischemic attack (TIA), coronary heart disease, and peripheral venous thrombosis was also ascertained.

RESULTS

We included 329 migraine patients and 329 control subjects (mean age 41 years, 77% women in both groups). Among migraine patients, 239 (72.6%) had migraine without aura and 90 (27.4%) had migraine with aura. Migraine patients had more frequently arterial hypertension, hypercholesterolemia, history of IS or TIA and, peripheral venous thrombosis compared to control subjects, whereas we found no differences in diabetes mellitus, BMI, and coronary heart disease between the two groups. At least one thrombophilic alteration was detected in 107 (32.5%) migraine patients and in 74 (22.5%) control subjects (OR = 1.66, 95% CI 1.17-2.35, p = 0.004). We identified an association of migraine with aPL positivity (OR = 2.6, 95% CI 1.5-4.7, p = 0.001) and with free protein S deficiency (OR = 4.7, 95% CI 1.6-14.0, p = 0.002), whereas we found no differences in protein C deficiency, APCR, and hyperhomocysteinemia between the two groups. Furthermore, aPL positivity and free protein S deficiency were more common in migraine patients with and without aura than in control subjects. We found that in migraine patients, aPL positivity was associated with both IS or TIA (OR = 5.6, 95% CI 1.5-20.4, p = 0.009) and with coronary heart disease (OR = 27.6, 95% CI 1.4-531.1, p = 0.028), whereas free protein S deficiency was associated with IS or TIA only (OR = 14.3, 95% CI 2.8-74.4, p = 0.002).

CONCLUSIONS

Our research documented a significative higher prevalence of aPL positivity and protein S deficiency in migraineurs than in controls. Data also showed an association between these alterations and some vascular thrombotic events in migraine patients. We can argue that thrombophilic disorders associated with migraine may contribute to the occurrence of vascular events.

Direct-to-consumer genetic testing for factor V Leiden and prothrombin 20210G>A: the consumer experience

Background

Clinical genetic testing for inherited predisposition to venous thromboembolism (VTE) is common among patients and their families. However, there is incomplete consensus about which individuals should receive testing, and the relative risks and benefits.

Methods

We assessed outcomes of receiving direct‐to‐consumer (DTC) results for the two most common genetic risk factors for VTE, factor V Leiden in the F5 gene (FVL) and prothrombin 20210G>A in the F2 gene (PT). Two thousand three hundred fifty‐four customers (1244 variant‐positive and 1110 variant‐negative individuals) of the personal genetics company 23andMe, Inc., who had received results online for F5 and F2 variants, participated in an online survey‐based study. Participants responded to questions about perception of VTE risk, discussion of results with healthcare providers (HCPs) and recommendations received, actions taken to control risk, emotional responses to receiving risk results, and perceived value of the information.

Results

Most participants (90% of variant‐positive individuals, 99% of variant‐negative individuals) had not previously been tested for F5 and/or F2 variants. The majority of variant‐positive individuals correctly perceived that they were at higher than average risk for developing VTE. These individuals reported moderate rates of discussing results with HCPs (41%); receiving prevention advice from HCPs (31%), and making behavioral changes to control risk (e.g., exercising more, 30%). A minority (36%) of variant‐positive individuals worried more after receiving VTE results. Nevertheless, most participants reported that knowing their risk had been an advantage (78% variant‐positive and 58% variant‐negative) and were satisfied knowing their genetic probability for VTE (81% variant‐positive and 67% variant‐negative).

Conclusion

Consumers reported moderate rates of behavioral change and perceived personal benefit from receiving DTC genetic results for VTE risk.

We assessed the consumer experience receiving direct‐to‐consumer (DTC) genetic risk for venous thromboembolism (VTE). 2354 customers (1244 variant‐positive and 1110 variant‐negative individuals) of the personal genetics company 23andMe, Inc., who had received results online for risk variants in clotting factor genes F2 and F5, participated in an online survey‐based study. Participants responded to questions about perception of VTE risk, discussion of results with healthcare providers and recommendations received, actions taken to control risk, emotional responses to receiving risk results, and perceived value of the information.

Genetic mutations associated with susceptibility to perioperative complications in a longitudinal biorepository with integrated genomic and electronic health records

BACKGROUND

Existing genetic information can be leveraged to identify patients with susceptibilities to conditions that might impact their perioperative care, but clinicians generally have limited exposure and are not trained to contextualise this information. We identified patients with genetic susceptibilities to anaesthetic complications using a perioperative biorepository and characterised the concordance with existing diagnoses.

METHODS

Adult patients undergoing surgery within Michigan Medicine from 2012 to 2017 were consented for genotyping. Genotypes were integrated with the electronic health record (EHR). We retrospectively characterised frequencies of variants associated with butyrylcholinesterase deficiency, factor V Leiden, and malignant hyperthermia, three pharmacogenetic factors with perioperative implications. We calculated the percentage homozygous and heterozygous for each that had been diagnosed previously and searched for EHR findings consistent with a predisposition.

RESULTS

Analysis of genetic data revealed that 25 out of 40 769 (0.1%) patients were homozygous and 1918 (4.7%) were heterozygous for mutations associated with butyrylcholinesterase deficiency. Of the homozygous individuals, 14 (56%) carried a pre-existing diagnosis. For factor V Leiden, 29 (0.1%) were homozygous and 2153 (5.3%) heterozygous. Of the homozygous individuals, three (10%) were diagnosed by EHR-derived phenotype and six (21%) by clinician review. Malignant hyperthermia was assessed in a subset of patients. We detected two patients with associated mutations. Neither carried clinical diagnoses.

CONCLUSIONS

We identified patients with genetic susceptibility to perioperative complications using an open source script designed for clinician use. We validated this application in a retrospective analysis for three conditions with well-characterised inheritance, and showed that not all genetic susceptibilities were documented in the EHR.

Direct blood PCR: TaqMan-probe based detection of the venous thromboembolism associated mutations factor V Leiden and prothrombin c.20210G>A without DNA extraction

BACKGROUND

Practically, the initial step of genetic analysis is the extraction of DNA from blood or other cells, which is often time consuming and cost-intensive. We aimed at establishing a real-time PCR protocol for the detection of the venous thromboembolism associated mutations factor V Leiden (F5 c.1691G>A; p.R506Q) and prothrombin (F2) c.20210G>A from whole blood, without DNA extraction.

METHODS

F5 c.1691G>A (p.R506Q) and F2 c.20210G>A mutations were determined in 205 EDTA anti-coagulated whole blood samples from patients who underwent routine clinical genotyping using the DirectBlood Genotyping PCR Kit (myPOLS Biotec, Konstanz, Germany) together with in-house developed TaqMan primer-probe assays.

RESULTS

Validity score values of genotype calls using whole blood were similar and did not significantly differ compared to those using genomic DNA as substrate in PCR. Mutation analysis of 205 whole blood samples showed a negligible PCR dropout rate (one in 410 reactions) and were in 100% concordance with results obtained by conventional genotyping.

CONCLUSION

We successfully established a robust and valid real-time PCR protocol for the detection of the venous thromboembolism associated mutations F5 c.1691G>A (p.R506Q) and F2 c.20210G>A directly from whole blood.

A Q-Probes Study Involving Utilization of Free Prostate-Specific Antigen, Factor V Leiden, and Hepatitis A Serology Tests

Context.—

Managing the utilization of laboratory tests is an important quality improvement activity that adds value to health care.

Objective.—

To examine utilization of 3 laboratory tests and identify factors that impact performance.

Design.—

Test utilization performance was evaluated by determining the frequency with which appropriate preconditions for testing were met. This included 30 testing episodes each involving (1) free prostate-specific antigen (PSA) when total PSA was within an appropriate interpretable range, (2) total anti–hepatitis A virus antibody when previous anti–hepatitis A virus antibody results were either negative or not done, and (3) factor V Leiden mutation when a previous result was not already available. Participants also provided information regarding some of their utilization policies and procedures for these 3 tests.

Results.—

The overall frequency with which testing criteria were met was 20.6% (163 of 790), 91.5% (649 of 709), and 95.2% (799 of 839) for free PSA, anti–hepatitis A virus antibody, and factor V Leiden, respectively. Utilization review was infrequent and done by 20.7% (6 of 29) of participants for factor V Leiden, 3.6% (1 of 28) for anti–hepatitis A virus antibody, and 3.6% (1 of 28) for free PSA. No practice or demographic characteristics were significantly associated with utilization performance for any test.

Conclusions.—

Utilization review was infrequent for the 3 tests examined. Variable amounts of unnecessary testing were observed for all tests, most frequently for free PSA, for which reporting results carried the added risk of diagnostic error from misinterpretation of results.

Economic Evaluations of Thrombophilia Screening Prior to Prescribing Combined Oral Contraceptives: A Systematic and Critical Review

BACKGROUND

Combined oral contraceptives (COCs) increase the risk of venous thromboembolism (VTE), particularly among women with inherited clotting disorders. The World Health Organization classifies combined hormonal contraception as an "unacceptable health risk" for women with thrombogenic mutations but advises against universal thrombophilia screening before prescribing COCs given the low prevalence of thrombophilia and high screening costs.

OBJECTIVE

Through the lens of lifetime costs and benefits, this paper systematically and critically reviews all published economic evaluations of thrombophilia screening prior to prescribing COCs.

METHODS

We searched relevant databases for economic evaluations of thrombophilia screening before prescribing COCs. After extracting the key study characteristics and economic variables, we evaluated each article using the Quality of Health Economic Studies (QHES) and the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) instruments.

RESULTS

Seven economic evaluations of thrombophilia screening before prescribing COCs met our inclusion criteria. Only the two economic evaluations focusing exclusively on selective screening exceeded the 75-point threshold for high-quality economic studies based on the QHES instrument, whereas only one of these exceeded the 85% CHEERS threshold. Only three of the seven economic evaluations performed sensitivity analysis on key parameters. Most studies underestimated the benefits of thrombophilia screening by comparing one-time costs of genetic screening against benefits per person-year, thus implicitly assuming a 1-year duration of COC use, neglecting the long-term implications of VTE and/or neglecting the lifetime benefits of awareness of inherited thrombophilia.

CONCLUSION

Our review highlights the lack of methodologically rigorous economic evaluations of universal thrombophilia screening before prescribing COCs.

Prognosis and Monitoring of VTE

Venous thromboembolism (VTE) can present in a variety of different clinical settings and in a diverse, comorbid patient population, both of which will guide the clinician toward the appropriate therapeutic response. Patients who present with pulmonary embolism are at risk for hemodynamic instability, recurrence of VTE, cardiac comorbidities, and increased risk of overall mortality. Prognostication models have been clinically validated for risk stratification and prediction of mortality. Similar to pulmonary embolism, patients with deep vein thrombosis carry a higher risk of VTE recurrence and cardiac comorbidities. Consequently, VTE can be treated by a variety of methods such as anticoagulants or inferior vena cava filters, which bear their own risks and benefits. It is imperative that clinicians monitor patients for complications from VTE and the chosen therapy.

A curated gene list for reporting results of newborn genomic sequencing

PURPOSE

Genomic sequencing (GS) for newborns may enable detection of conditions for which early knowledge can improve health outcomes. One of the major challenges hindering its broader application is the time it takes to assess the clinical relevance of detected variants and the genes they impact so that disease risk is reported appropriately.

METHODS

To facilitate rapid interpretation of GS results in newborns, we curated a catalog of genes with putative pediatric relevance for their validity based on the ClinGen clinical validity classification framework criteria, age of onset, penetrance, and mode of inheritance through systematic evaluation of published evidence. Based on these attributes, we classified genes to guide the return of results in the BabySeq Project, a randomized, controlled trial exploring the use of newborn GS (nGS), and used our curated list for the first 15 newborns sequenced in this project.

RESULTS

Here, we present our curated list for 1,514 gene-disease associations. Overall, 954 genes met our criteria for return in nGS. This reference list eliminated manual assessment for 41% of rare variants identified in 15 newborns.

CONCLUSION

Our list provides a resource that can assist in guiding the interpretive scope of clinical GS for newborns and potentially other populations.Genet Med advance online publication 12 January 2017.

Guidance for the evaluation and treatment of hereditary and acquired thrombophilia

Thrombophilias are hereditary and/or acquired conditions that predispose patients to thrombosis. Testing for thrombophilia is commonly performed in patients with venous thrombosis and their relatives; however such testing usually does not provide information that impacts management and may result in harm. This manuscript, initiated by the Anticoagulation Forum, provides clinical guidance for thrombophilia testing in five clinical situations: following 1) provoked venous thromboembolism, 2) unprovoked venous thromboembolism; 3) in relatives of patients with thrombosis, 4) in female relatives of patients with thrombosis considering estrogen use; and 5) in female relatives of patients with thrombosis who are considering pregnancy. Additionally, guidance is provided regarding the timing of thrombophilia testing. The role of thrombophilia testing in arterial thrombosis and for evaluation of recurrent pregnancy loss is not addressed. Statements are based on existing guidelines and consensus expert opinion where guidelines are lacking. We recommend that thrombophilia testing not be performed in most situations. When performed, it should be used in a highly selective manner, and only in circumstances where the information obtained will influence a decision important to the patient, and outweigh the potential risks of testing. Testing should not be performed during acute thrombosis or during the initial (3-month) period of anticoagulation.

Pre-examination factors affecting molecular diagnostic test results and interpretation: A case-based approach

BACKGROUND

Multiple organizations produce guidance documents that provide opportunities to harmonize quality practices for diagnostic testing. The International Organization for Standardization ISO 15189 standard addresses requirements for quality in management and technical aspects of the clinical laboratory. One technical aspect addresses the complexities of the pre-examination phase prior to diagnostic testing.

METHODS

The Committee for Molecular Diagnostics of the International Federation for Clinical Chemistry and Laboratory Medicine (also known as, IFCC C-MD) conducted a survey of international molecular laboratories and determined ISO 15189 to be the most referenced guidance document. In this review, the IFCC C-MD provides case-based examples illustrating the value of select pre-examination processes as these processes relate to molecular diagnostic testing. Case-based examples in infectious disease, oncology, inherited disease and pharmacogenomics address the utility of: 1) providing information to patients and users, 2) designing requisition forms, 3) obtaining informed consent and 4) maintaining sample integrity prior to testing.

CONCLUSIONS

The pre-examination phase requires extensive and consistent communication between the laboratory, the healthcare provider and the end user. The clinical vignettes presented in this paper illustrate the value of applying select ISO 15189 recommendations for general laboratory to the more specialized area of Molecular Diagnostics.

The Evaluation of Serum Copeptin Levels and Some Commonly Seen Thrombophilic Mutation Prevalence in Acute Pulmonary Embolism

Acute pulmonary embolism (PE) is a common, emergent condition and may affect a large number of patients. Copeptin has been indicated to be a sensitive biomarker of arginine vasopressin release, and has diagnostic and prognostic value in various clinical conditions. Genetic mutations are considerable components of thrombophilic diseases, and factor II gene G20210A, (FII20210A), factor V Leiden (FVL, G1691A) and methylenetetrahydrofolate reductase gene C677T (MTHFR677T) single nucleotide polymorphisms are the most common mutations of thrombophilic diseases. In this study, serum copeptin levels were determined in patients with PE and healthy controls, and the results were discussed. The prevalence of some commonly seen thrombophilic mutations was also evaluated in patients with PE. The study included 32 patients (18 male, 14 female) with PE and 24 (13 male, 11 female) age- and gender-matched healthy controls. A significant difference in serum copeptin levels was determined between the patient and control groups (8.58 ± 4.42 and 4.07 ± 1.02 pmol/L, respectively). Heterozygous mutant genotype for FII20210A and heterozygous mutant genotype for FVL were observed in 3.1 and 9.4% of patients, respectively. Mutant genotype of 49% was determined for MTHFR677T mutations. It was concluded that copeptin may have diagnostic value for PE.

Genetic Risk Factors in Venous Thromboembolism

Genetic risk factors predispose to thrombophilia and play the most important etiopathogenic role in venous thromboembolism (VTE) in people younger than 50 years old. At least one inherited risk factor could be found in about half of the cases with a first episode of idiopathic VTE.Roughly, genetic risk factors are classified into two main categories: loss of function mutations (such as deficiencies of antithrombin, protein C, protein S) and gain of function mutations, (such as prothrombin mutation G20210A, factor V Leiden). A revolutionary contribution to the genetic background of VTE was brought by the achievements of the genome-wide association studies which analyze the association of a huge number of polymorphisms in large sample size.Hereditary thrombophilia testing should be done only in selected cases. The detection of hereditary thrombophilia has impact on the management of the anticoagulation in children with purpura fulminans, pregnant women at risk of VTE and may be useful in the assessment of the risk for recurrent thrombosis in patients presenting an episode of VTE at a young age (<40 years) and in cases with positive family history regarding thrombosis.

Expanded carrier screening in reproductive medicine-points to consider: a joint statement of the American College of Medical Genetics and Genomics, American College of Obstetricians and Gynecologists, National Society of Genetic Counselors, Perinatal Quality Foundation, and Society for Maternal-Fetal Medicine

The Perinatal Quality Foundation and the American College of Medical Genetics and Genomics, in association with the American College of Obstetricians and Gynecologists, the Society for Maternal-Fetal Medicine, and the National Society of Genetic Counselors, have collaborated to provide education for clinicians and laboratories regarding the use of expanded genetic carrier screening in reproductive medicine. This statement does not replace current screening guidelines, which are published by individual organizations to direct the practice of their constituents. As organizations develop practice guidelines for expanded carrier screening, further direction is likely. The current statement demonstrates an approach for health care providers and laboratories who wish to or who are currently offering expanded carrier screening to their patients.

Family history unawareness of blood clot risk: links to misdiagnoses and illness uncertainties in personal and expert realms

The difficulty of diagnosing blood clots makes salient the question, "What role does family history awareness have for guiding lay and expert actions?" The authors examine the in-depth life reflection interviews of 20 women who experienced a first venous blood clot between the ages of 18 and 50 years, identifying causal attributions the women made for thrombosis after the event. Twelve participants described an understanding of the cascade of events linked to thrombosis, revealing that there is seldom a single cause. The other eight identified belief in a single determining cause for their thrombosis. The authors reflect on the symptoms the women experienced during the course of the clotting event, patterns of care that they executed to self-manage their blood clot, and their misdiagnoses associated with symptoms and care. The women recalled the patterns of care received through formal health care systems and the reported misdiagnoses linked to these interactions. The recollections reveal that the subtle nature of venous blood clot symptoms contributes to lay and expert misdiagnoses. Use of antibiotics and pain killers in the wake of misdiagnosis masks symptoms, contributing to costly delays in accurate diagnoses. Four women were aware of a family history of clotting when the event occurred, 13 had such a history but lacked awareness until the clotting event, and three had no known history. Among women with awareness of their family history, blood clot diagnosis occurred sooner, promoting survival and efficiencies in health care. Implications for communicating about family history of thrombosis are considered.

Recurrent pregnancy loss in a subject with heterozygote factor V Leiden mutation; a case report

Recurrent pregnancy loss is usually defined as the loss of two or more consecutive pregnancies before 20 weeks of gestation, which occurs in approximately 5% of reproductive-aged women. It has been suggested that women with thrombophilia have an increased risk of pregnancy loss and other adverse pregnancy outcomes. Thrombophilia is an important predisposition to blood clot formation and is considered as a significant risk factor for recurrent pregnancy loss. The inherited predisposition to thrombophilia is most often associated with factor V Leiden mutation, prothrombin G20210A mutation, and methylenetetrahydrofolate reductase C677T and A1298C gene variants. The net effect is an increased cleavage of prothrombin to thrombin and excessive blood coagulation.

New molecular genetic tests in the diagnosis of heart disease

With the increasing use of next-generation sequencing applications, there has been an increase in identification of genetic causes of cardiac disease. This technology has also enabled the transition of these genes into the clinical setting and the rapid growth of large gene tests for the diagnosis of heart disorders. The ability to combine tests to include similar, but distinct, diseases has shown that many genes can be responsible for a wide variety of both syndromic and nonsyndromic disorders. This article discusses the current state of molecular genetic diagnosis for cardiac disorders, focusing on diseases with mendelian inheritance.

Development and integration of molecular genetic tests into clinical practice: the US experience

The issues that arise in the development of genetic tests for prediction and diagnosis are described in the context of the authors' experience as laboratory directors in the USA. The goal is to identify gaps and weaknesses in the test validation process and to define the pivotal issues. Variables that influence a laboratory director's decision to develop a particular molecular genetic assay, including motivation, economics, intellectual property and the regulatory environment, are described. Issues of clinical and analytic validation are discussed, providing examples of tests with both good (cystic fibrosis carrier screening) and poor (apolipoprotein E genotyping for Alzheimer's disease) clinical utility. The decision-making process that occurs during the considered transition of a research-based molecular genetic assay into routine use in the clinical laboratory is summarized. Different factors will be weighted differently depending on the nature of the disease being tested, the complexity of its gene and mutations, the available technical platforms, potential regulatory and intellectual property restrictions, and whether the proposed test is to be offered by an academic or a commercial laboratory.

Laboratory informatics based evaluation of methylene tetrahydrofolate reductase C677T genetic test overutilization

Background:

Laboratory data can provide a wide range of information to estimate adherence to guidelines and proper utilization of genetic testing. The methylene tetrahydrofolate reductase (MTHFR) C677T variant has been demonstrated to have negligible utility in patient management. However, the testing of this variant remains pervasive. The purpose of this study was to develop methods to analyze concordance of clinician ordering practices with national guidelines.

Methods:

We used laboratory data to extract specific data elements including patient demographics, timestamps, physician ordering logs and temporal relationship to chemistry requests to examine 245 consecutive MTHFR tests ordered in 2011 at an academic tertiary center. A comprehensive chart review was used to identify indications for testing. These results were correlated with a retrospective analysis of 4,226 tests drawn at a range of hospitals requesting testing from a national reference laboratory over a 2-year period. MTHFR ordering practices drawn from 17 institutions were examined longitudinally from 2002 to 2011.

Results:

Indications for testing included cerebrovascular events (40.0%) and venous thrombosis (39.1%). Family history prompted testing in eight cases. Based on acceptable hypercoagulability guidelines recommending MTHFR C677T testing only in the presence of elevated serum homocysteine, 10.6% (22/207) of adult patients met an indicated threshold at an academic tertiary center. Among 77 institutions, 14.5% (613/4226) of MTHFR testing met recommendations.

Conclusion:

We demonstrate an effective method to examine discreet elements of a molecular diagnostics laboratory information system at a tertiary care institution and to correlate these findings at a national level. Retrospective examination of clinicians’ request of MTHFR C677T genetic testing strongly suggests that clinicians have failed to adjust their ordering practices in light of evolving scientific and professional organization recommendations.

Processes and preliminary outputs for identification of actionable genes as incidental findings in genomic sequence data in the Clinical Sequencing Exploratory Research Consortium

As genomic and exomic testing expands in both the research and clinical arenas, determining whether, how, and which incidental findings to return to the ordering clinician and patient becomes increasingly important. Although opinion is varied on what should be returned to consenting patients or research participants, most experts agree that return of medically actionable results should be considered. There is insufficient evidence to fully inform evidence-based clinical practice guidelines regarding return of results from genome-scale sequencing, and thus generation of such evidence is imperative, given the rapidity with which genome-scale diagnostic tests are being incorporated into clinical care. We present an overview of the approaches to incidental findings by members of the Clinical Sequencing Exploratory Research network, funded by the National Human Genome Research Institute, to generate discussion of these approaches by the clinical genomics community. We also report specific lists of "medically actionable" genes that have been generated by a subset of investigators in order to explore what types of findings have been included or excluded in various contexts. A discussion of the general principles regarding reporting of novel variants, challenging cases (genes for which consensus was difficult to achieve across Clinical Sequencing Exploratory Research network sites), solicitation of preferences from participants regarding return of incidental findings, and the timing and context of return of incidental findings are provided.Genet Med 15 11, 860-867.Genetics in Medicine (2013); 15 11, 860-867. doi:10.1038/gim.2013.133.

An improved algorithm for activated protein C resistance and factor V Leiden screening

OBJECTIVES

To evaluate the performance of a Russell viper venom-based activated protein C resistance (APCR) screening test relative to DNA analysis for the factor V Leiden mutation.

METHODS

We evaluated the concordance between Pefakit APCR screening results and DNA analysis for 435 patients homozygous (n = 11), heterozygous (n = 310), or wild-type (n =114) for the G1691A allele.

RESULTS

Using receiver operating characteristic analysis, we found that a cutoff of 1.89 for the APCR ratio yields a sensitivity and specificity of 99.1%. In patients with discrepant genotype-phenotype correlation, their APCR may provide a more clinically relevant result.

CONCLUSIONS

We compared several strategies for employing reflex testing and found that performing initial APCR screening followed by confirmatory molecular analysis on a subset of cases in the borderline regions between the diagnostic groups can reduce unnecessary testing by approximately 80% without compromising diagnostic accuracy.

Genetic screening for the predisposition to venous thromboembolism: a cost-utility analysis of clinical practice in the Italian health care system

OBJECTIVES

In the Italian health care system, genetic tests for factor V Leiden and factor II are routinely prescribed to assess the predisposition to venous thromboembolism (VTE) of women who request oral contraception. With specific reference to two subpopulations of women already at risk (i.e., familial history or previous event of VTE), the study aimed to assess whether current screening practices in Italy are cost-effective.

METHODS

Two decisional models accrued costs and quality-adjusted life-years (QALY) annually from the perspective of the National Health Service. The two models were derived from a decision analysis exercise concerning testing practices and consequent prescribing behavior for oral contraception conducted with 250 Italian gynecologists. Health care costs were compiled on the basis of 10-year hospital discharge records and the activities of a thrombosis center. Whenever possible, input data were based on the Italian context; otherwise, the data were taken from the international literature.

RESULTS

Current testing practices on women with a familial history of VTE generate an incremental cost-effectiveness ratio of €72,412/QALY, which is well above the acceptable threshold of cost-effectiveness of €40,000 to €50,000/QALY. In the case of women with a previous event of VTE, the most frequently used testing strategy is cost-ineffective and leads to an overall loss of QALY.

CONCLUSIONS

This study represents the first attempt to conduct a cost-utility analysis of genetic screening practices for the predisposition to VTE in the Italian setting. The results indicate that there is an urgent need to better monitor the indications for which tests for factor V Leiden and factor II are prescribed.

Testing for inherited thrombophilia and consequences for antithrombotic prophylaxis in patients with venous thromboembolism and their relatives. A review of the Guidelines from Scientific Societies and Working Groups

The clinical penetrance of venous thromboembolism (VTE) susceptibility genes is variable, being lower in heterozygous carriers of factor V Leiden and prothrombin 20210A (mild thrombophilia), and higher in the rare carriers of deficiencies of antithrombin, protein C or S, and those with multiple or homozygous abnormalities (high-risk thrombophilia). The absolute risk of VTE is low, and the utility of laboratory investigation for inherited thrombophilia in patients with VTE and their asymptomatic relatives has been largely debated, leading to the production of several Guidelines from Scientific Societies and Working Groups. The risk for VTE largely depends on the family history of VTE. Therefore, indiscriminate search for carriers is of no utility, and targeted screening is potentially more fruitful. In patients with VTE inherited thrombophilia is not scored as a determinant of recurrence, playing a minor role in the decision of prolonging anticoagulation; indeed, a few guidelines consider testing worthwhile to identify carriers of high-risk thrombophilia, particularly those with a family history of VTE. The identification of the asymptomatic carrier relatives of the probands with VTE and thrombophilia could reduce cases of provoked VTE, offering them primary antithrombotic prophylaxis during risk situations. In most guidelines, this is considered justified only for relatives of probands with a deficiency of natural anticoagulants or multiple abnormalities. Counselling the asymptomatic female relatives of individuals with VTE and/or thrombophilia before pregnancy or the prescription of hormonal treatments should be administered with consideration of the risk driven by the type of thrombophilia and the family history of VTE.

ACMG Practice Guideline: lack of evidence for MTHFR polymorphism testing

MTHFR polymorphism testing is frequently ordered by physicians as part of the clinical evaluation for thrombophilia. It was previously hypothesized that reduced enzyme activity of MTHFR led to mild hyperhomocysteinemia which led to an increased risk for venous thromboembolism, coronary heart disease, and recurrent pregnancy loss. Recent meta-analyses have disproven an association between hyperhomocysteinemia and risk for coronary heart disease and between MTHFR polymorphism status and risk for venous t-hromboembolism. There is growing evidence that MTHFR polymorphism testing has minimal clinical utility and, therefore should not be ordered as a part of a routine evaluation for thrombophilia.

Pharmacogenetic typing for oral anti-coagulant response among factor V Leiden mutation carriers

CONTEXT

Factor V Leiden mutation is the most common inherited predisposition for hypercoagulability and thereby a common genetic cause for initiation of oral anti-coagulation therapy. There is a dearth of knowledge of coumarin response profile in such thrombophilic population.

AIMS

The current pilot study aims to estimate coumarin sensitivity in an Indian cohort with an inherited thrombophilia risk factor (Factor V Leiden mutation carriers) based on the observed frequency of CYP2C9 (*)2, (*)3 and VKORC1-1639G >A genotype combinations.

SETTINGS AND DESIGN

A retrospective study carried out in a tertiary health care center in India.

MATERIALS AND METHODS

Carriers of FVL mutation were genotyped for CYP2C9 ((*)2, F(*)3) and VKORC1 (-1639G >A) variants by PCR-RFLP technique.

STATISTICAL ANALYSIS USED

Chi-square test to analyze difference in expected and observed genotype frequency.

RESULTS

Sixty-one (n = 61) unrelated carriers of FVL mutation were observed in the 13 years study period. The allele frequency of CYP2C9 (*)2, CYP2C9 (*)3, and VKORC1-1639A in this cohort was 0.06, 0.11, and 0.16, respectively. Six (9.7%) individuals had two of the three variant alleles (heterozygous or homozygous), and 28 (45.9%) were heterozygous for at least one polymorphism.

CONCLUSIONS

Pre-prescription genotyping for coumarin drugs, if introduced in Indians with inherited thrombophilia (in whom oral anti-coagulant therapy may be necessary), is likely to identify 9.7% (hypersensitive) subjects in whom the optimum anti-coagulation may be achieved with reduced dosages, 44.3% (normal sensitivity) who may require higher dose and also 55.6% (hyper and moderate sensitivity) subjects who are likely to experience bleeding episodes.

The Obstetric Medicine Listserv: review of controversies surrounding thrombophilia testing

A woman with no significant personal or family history of thrombosis asked her internist to obtain a thrombophilia work-up prior to starting the combined oral contraceptive for dysmenorrhoea, after another physician advised her to have the test. The case was sent to an international email discussion group where the consensus was that testing should not be done. The responses of the group and review of this controversial topic are presented.

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.

Factor V Leiden thrombophilia

Factor V Leiden is a genetic disorder characterized by a poor anticoagulant response to activated Protein C and an increased risk for venous thromboembolism. Deep venous thrombosis and pulmonary embolism are the most common manifestations, but thrombosis in unusual locations also occurs. The current evidence suggests that the mutation has at most a modest effect on recurrence risk after initial treatment of a first venous thromboembolism. Factor V Leiden is also associated with a 2- to 3-fold increased relative risk for pregnancy loss and possibly other obstetric complications, although the probability of a successful pregnancy outcome is high. The clinical expression of Factor V Leiden is influenced by the number of Factor V Leiden alleles, coexisting genetic and acquired thrombophilic disorders, and circumstantial risk factors. Diagnosis requires the activated Protein C resistance assay (a coagulation screening test) or DNA analysis of the F5 gene, which encodes the Factor V protein. The first acute thrombosis is treated according to standard guidelines. Decisions regarding the optimal duration of anticoagulation are based on an individualized assessment of the risks for venous thromboembolism recurrence and anticoagulant-related bleeding. In the absence of a history of thrombosis, long-term anticoagulation is not routinely recommended for asymptomatic Factor V Leiden heterozygotes, although prophylactic anticoagulation may be considered in high-risk clinical settings. In the absence of evidence that early diagnosis reduces morbidity or mortality, decisions regarding testing at-risk family members should be made on an individual basis.

Speaking the Language of Genetics: A Primer

Genetic research advances will continue to result in clinical applications for genetics in primary care settings. Fluency with the evolving genetic terminology will enable primary care providers to provide better clinical care to their patients, particularly when helping patients understand genetic concepts. This article will help clinicians use genetic terminology with greater precision.

Usefulness of factor V Leiden mutation testing in clinical practice

We have investigated the clinical usefulness of the activated protein C resistance (APCR)/factor V Leiden mutation (FVL) test by sending out questionnaires to all Norwegian physicians who ordered these tests from our publicly funded service laboratory during a 3-month period, and of whom 70% (267/383) responded. Indications for testing, patient follow-up, the use of APCR versus FVL tests and differences in practice between hospital doctors and GPs were examined. We found that 46% of the tests were predictive, ordered for risk assessment in healthy individuals with no previous history of venous thromboembolism (VTE). Among these, 42% of the tests were taken on the initiative of the patient and 24% were screening tests before prescription of oral contraceptives. In total, 54% of the tests were classified as diagnostic, among which 42% were ordered owing to a previous history of VTE and 22% to a history of brain stroke or myocardial infarction. The prevalence of FVL heterozygotes was not significantly different between the predictive and diagnostic test groups, that is, 26 and 20%, respectively. Only the predictive tests influenced patient follow-up. Here, the physician's advice to patients depended on the test result. In general, the clinical usefulness of APCR/FVL testing was low. Many tests were performed on unsubstantiated or vague indications. Furthermore, normal test results led to unwarranted refrain from giving advice about antithrombotic measures, leading to potential harm to the patient.