Genetics of venous thrombosis

Quantitative protein mass spectrometry for multiplex measurement of coagulation and fibrinolytic proteins towards clinical application: What, why and how?

Plasma proteins involved in coagulation and fibrinolysis are essential to hemostasis. Consequently, their circulating levels and functionality are critical in bleeding and thrombosis development. Well-established laboratory tests to assess these are available; however, said tests do not allow high multiplicity, require large volumes of plasma and are often costly. A novel technology to quantify plasma proteins is quantitative protein mass spectrometry (QPMS). Aided by stable isotope-labeled internal standards a large number of proteins can be quantified in one single analytical run requiring <30 μL of plasma. This provides an opportunity to improve insight in the etiology and prognosis of bleeding and thrombotic disorders, in which the balance between different proteins plays a crucial role. This manuscript aims to give an overview of the QPMS potential applications in thrombosis and hemostasis research (quantifying the 38 proteins assigned to coagulation and fibrinolysis by the KEGG database), but also to explore the potential and hurdles if designed for clinical practice. Advantages and limitations of QPMS are described and strategies for improved analysis are proposed, using as an example the test requirements for antithrombin. Application of this technology in the future could represent a step towards individualized patient care.

Thrombosis risk in single- and double-heterozygous carriers of factor V Leiden and prothrombin G20210A in FinnGen and the UK Biobank

ABSTRACT

The factor V Leiden (FVL; rs6025) and prothrombin G20210A (PTGM; rs1799963) polymorphisms are 2 of the most well-studied genetic risk factors for venous thromboembolism (VTE). However, double heterozygosity (DH) for FVL and PTGM remains poorly understood, with previous studies showing marked disagreement regarding thrombosis risk conferred by the DH genotype. Using multidimensional data from the UK Biobank (UKB) and FinnGen biorepositories, we evaluated the clinical impact of DH carrier status across 937 939 individuals. We found that 662 participants (0.07%) were DH carriers. After adjustment for age, sex, and ancestry, DH individuals experienced a markedly elevated risk of VTE compared with wild-type individuals (odds ratio [OR] = 5.24; 95% confidence interval [CI], 4.01-6.84; P = 4.8 × 10-34), which approximated the risk conferred by FVL homozygosity. A secondary analysis restricted to UKB participants (N = 445 144) found that effect size estimates for the DH genotype remained largely unchanged (OR = 4.53; 95% CI, 3.42-5.90; P < 1 × 10-16) after adjustment for commonly cited VTE risk factors, such as body mass index, blood type, and markers of inflammation. In contrast, the DH genotype was not associated with a significantly higher risk of any arterial thrombosis phenotype, including stroke, myocardial infarction, and peripheral artery disease. In summary, we leveraged population-scale genomic data sets to conduct, to our knowledge, the largest study to date on the DH genotype and were able to establish far more precise effect size estimates than previously possible. Our findings indicate that the DH genotype may occur as frequently as FVL homozygosity and may confer a similarly increased risk of VTE.

Frequencies of VKORC1-1639G>A and rs397509427 in Patients on Warfarin and Healthy Syrian Subjects

Background

Vitamin K epoxide reductase complex subunit 1 (VKORC1) gene encodes a key enzyme with multiple cellular activities, namely, the reduction of vitamin K to its active form. VKORC1-1639G>A (rs9923231) is a common single nucleotide polymorphism with a crucial impact on warfarin dosing and possibly other physiological functions. This study aimed at investigating the frequencies of VKORC1-1639G>A alleles and genotypes in Syrian healthy subjects and patients on warfarin for different indications.

Methods

A total of 138 individuals were enrolled in this cross-sectional study. Genomic DNA was extracted from both patients on warfarin and healthy subjects, and polymerase chain reaction (PCR) specific amplicons were genotyped via standard sequencing which also allowed the detection of rs397509427. Comparisons of -1639G>A frequency with other populations were drawn.

Results

Of 94 patients on warfarin, 53 (56.38%) were with idiopathic venous thromboembolism (VTE). Despite comparable frequencies of the -1639A allele (47% and 50%), the AA and GA genotypes were at disparate frequencies of 93.2% versus 79.8% in the healthy subjects (n = 44) versus patients on warfarin, respectively. Carriers of the GG genotype were at a four-fold increased risk of VTE in comparison with those of the AA and GA genotypes (odds ratio (OR) = 4, 95% CI = 1.105 - 13.6, P = 0.0469). All study subjects were wild-type for the rs397509427 variant.

Conclusions

Our results prove a high -1639A prevalence in Syrian healthy subjects and patients on warfarin at frequencies comparable to other Mediterranean and Middle Eastern populations. The A allele carriers are at a lower VTE risk, whereas a global prevalence gradient of the G allele is suggested to be associated with VTE risk.

Risk assessment of venous thromboembolism in inflammatory bowel disease by inherited risk in a population-based incident cohort

BACKGROUND

Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is a chronic inflammatory disease of the digestive tract with increasing prevalence globally. Although venous thromboembolism (VTE) is a major complication in IBD patients, it is often underappreciated with limited tools for risk stratification.

AIM

To estimate the proportion of VTE among IBD patients and assess genetic risk factors (monogenic and polygenic) for VTE.

METHODS

Incident VTE was followed for 8465 IBD patients in the UK Biobank (UKB). The associations of VTE with F5 factor V leiden (FVL) mutation, F2 G20210A prothrombin gene mutation (PGM), and polygenic score (PGS003332) were tested using Cox hazards regression analysis, adjusting for age at IBD diagnosis, gender, and genetic background (top 10 principal components). The performance of genetic risk factors for discriminating VTE diagnosis was estimated using the area under the receiver operating characteristic curve (AUC).

RESULTS

The overall proportion of incident VTE was 4.70% in IBD patients and was similar for CD (4.46%), UC (4.49%), and unclassified (6.42%), and comparable to that of cancer patients (4.66%) who are well-known at increased risk for VTE. Mutation carriers of F5/F2 had a significantly increased risk for VTE compared to non-mutation carriers, hazard ratio (HR) was 1.94, 95% confidence interval (CI): 1.42-2.65. In contrast, patients with the top PGS decile had a considerably higher risk for VTE compared to those with intermediate scores (middle 8 deciles), HR was 2.06 (95%CI: 1.57-2.71). The AUC for differentiating VTE diagnosis was 0.64 (95%CI: 0.61-0.67), 0.68 (95%CI: 0.66-0.71), and 0.69 (95%CI: 0.66-0.71), respectively, for F5/F2 mutation carriers, PGS, and combined.

CONCLUSION

Similar to cancer patients, VTE complications are common in IBD patients. PGS provides more informative risk information than F5/F2 mutations (FVL and PGM) for personalized thromboprophylaxis.

Cancer-associated thrombosis by cancer sites and inherited factors in a prospective population-based cohort

Cancer-associated thrombosis (CAT) is common and associated with mortality. We estimated CAT rate by cancer sites and inherited factors among cancer patients from the UK Biobank (N =70,406). The 12-month CAT rate after cancer diagnosis was 2.37% overall but varied considerably among cancer sites. Among the 10 cancer sites classified as 'high-risk' of CAT by the National Comprehensive Cancer Network guidelines, 6 had CAT rate <5%. In contrast, 5 cancer sites classified as 'average-risk' by the guidelines had CAT rate >5%. For inherited risk factors, both known mutation carriers in two genes (F5/F2) and polygenic score for venous thromboembolism (VTE) (PGSVTE) were independently associated with increased CAT risk. While F5/F2 identified 6% patients with high genetic-risk for CAT, adding PGSVTE identified 13 % patients at equivalent/higher genetic-risk to CAT than that of F5/F2 mutations. Findings from this large prospective study, if confirmed, provide critical data to update guidelines for CAT risk assessment.

Role of tissue factor pathway inhibitor in hormone-induced venous thromboembolism

ABSTRACT

Exposure to higher levels of steroid hormones, like that in pregnancy or during combined hormonal contraception, increases the risk of venous thromboembolism. Development of resistance to activated protein C (APC) thought to be the underlying pathomechanism of this prothrombotic state. This coagulation phenomena is largely to be explained by the hormone-induced impairment of the protein S/ tissue factor pathway inhibitor (TFPI) leading to a less efficient inactivation of factor Va and factor VIIIa by APC. APC resistance and decreased protein S/TFPI function were associated with the risk of first as well as recurrent venous thromboembolism. Preexisting disturbances in these pathways are likely to predispose to thrombosis during hormone exposure and can persist over years after the thrombosis event.Further studies are necessary to investigate the predictive value of forgoing APC resistance and decreased protein S/TFPI function or an excessive alteration in these parameters during hormone intake on the development of hormone-induced venous thromboembolism.

A Retrospective Analysis of the Postoperative Effect of Intraoperative Hypothermia on Deep Vein Thrombosis After Intracranial Tumor Resection

BACKGROUND

Deep venous thrombosis (DVT) is a common clinical vascular disease, and post-thrombotic syndrome is usually the complication of patients. This study was to explore the relationship between intraoperative hypothermia and DVT.

METHODS

Patients who were clinically diagnosed with intracranial tumors and underwent tumors resection from January 2019 to March 2021 were studied and divided into the DVT and non-DVT group. Prothrombin time, activated partial prothrombin time (ATPP), thrombin time, plasma fibrinogen, and venous flow velocity of both lower limbs were measured to observe DVT and the incidence of DVT. Univariate and multivariate logistic regression analyses were used to investigate the correlation between intraoperative hypothermia and DVT, and to analyze the DVT-related risk factors.

RESULTS

A total of 462 patients were analyzed, of whom 231 patients were allocated to the DVT group and 231 were in the non-DVT group. Within the DVT group, 156 patients (33.8%) experienced intraoperative hypothermia. The risk factors that were significantly correlated with DVT were age, sex, operation time, ATPP value, and intraoperative hypothermia. The decreased ATPP value was found to be significantly associated with the increased incidence of DVT, and older ages (>45 years) were highly associated with DVT. Low body temperature before operation and intraoperative hypothermia were statistically significant as well. In addition, significant association was also displayed between the patient's operation time (>350 minutes) and DVT.

CONCLUSION

Patients who underwent intracranial tumor resection experience a high incidence of DVT, and patients with intraoperative hypothermia are at greater risk of DVT.

Systematic Review and Meta-Analysis of the Susceptibility of ABO Blood Groups to Venous Thromboembolism in Individuals with Factor V Leiden

A limited number of studies investigated the association between the ABO blood groups and the incidence of venous thromboembolism in individuals with Factor V Leiden; however, discordant findings were reported. Consequently, this systematic review and meta-analysis aimed to evaluate the existing evidence on the susceptibility of the ABO blood group to venous thromboembolism in individuals with Factor V Leiden. All English-published articles on the Web of Science, Scopus, PubMed, EMBASE, and Google Scholar were comprehensively and systematically searched by the author without a time or region limit. Four studies were included in the qualitative synthesis and meta-analysis after the removal of studies that were not eligible. According to the analyses of the fixed and random effects, the point estimates of the effect size and the 95% confidence interval were 0.416 (95% CI: 0.397−0.435) and 0.392 (95% CI: 0.288−0.507), respectively. In contrast, the homogeneity test (Q value) reveals that blood group data distributions have a heterogenous structure (Q = 432.187; p-value < 0.001). The pooled event rates and the 95% CIs for the A, AB, B, and O-blood groups were 0.518 (95% CI: 0.411−0.622), 0.592 (95% CI: 0.495−0.683), 0.205 (95% CI: 0.041−0.612), and 0.283 (95% CI: 0.247−0.322), respectively. According to the findings, people with Factor V Leiden with blood group AB are more likely to develop venous thromboembolism than those with blood groups A, O, and B. The overall statistical significance of the ABO blood group’s susceptibility to venous thromboembolism in individuals with Factor V Leiden was <0.001 (pooled p-value). In conclusion, the current meta-analysis provides an additional indication that blood group AB individuals with Factor V Leiden are at higher risk of developing venous thromboembolism, and blood type B is connected to a lower risk of developing venous thromboembolism.

Large-scale screening for factor V Leiden (G1691A), prothrombin (G20210A), and MTHFR (C677T) mutations in Greek population

Background and aims

To provide a fair estimate of the prevalence of factor V Leiden (FVL) (G1691A), prothrombin (G20210A), and MTHFR (C677T) mutations in the Greek population.

Methods

We genotyped a representative sample of 974 apparently healthy Greek adults by the method of real-time PCR and we calculated the allele frequencies of factor V Leiden (FVL) (G1691A), prothrombin (G20210A), and MTHFR (C677T) mutations. In addition, we determined the frequency of co-occurrence of FVL (1691A) and prothrombin (20210A), FVL (1691A) and MTHFR (677T), prothrombin (20210A) and MTHFR (677T) mutations.

Results

Τhe career frequencies of FVL (1691A), prothrombin (20210A), and MTHFR (677T) alleles were 7.5%, 4.5%, and 49.3% while the allele frequencies were 4%, 2.25%, and 39.5%, respectively. The coexistence of the allele frequencies combinations of two, FVL (1691A) and Prothrombin (20210A), FVL (1691A) and MTHFR (677T), prothrombin (20210A) and MTHFR (677T) was found in 1 (0.9%), 29 (3.5%), and 22 (3%) samples, respectively. Triple heterozygous carriers were not found.

Conclusion

Allele frequencies of the two (FVL and MTHFR) mutations are higher compared with published data. The large sample size of our study enhances the validity of our results and suggests a biological affinity of Greek population with Southern Italian populations.

Dabigatran in Cerebral Sinus Vein Thrombosis and Thrombophilia

Background and Purpose: Thrombophilic gene alterations are a major risk factor for cerebral sinus vein thrombosis (CSVT). Up to 30% of all patients with cerebral sinus vein thrombosis (CSVT) are found to have thrombophilic defects such as prothrombin mutation (PTM) or factor V Leiden (FVL). Their repercussions on the plasma levels of dabigatran etexilate are unclear. In this prospective case–control study, we aimed to investigate whether thrombophilia in CSVT has an influence on dabigatran peak-plasma levels. Methods: We monitored 10 patients over 12 months with acute CSVT, genetic thrombophilia with off-label use of dabigatran etexilate 150 mg twice a day and measured dabigatran peak-plasma levels and radiological outcome. We also monitored patients without genetic thrombophilia with dabigatran etexilate 150 mg twice a day and compared the efficiency and dabigatran peak-plasma levels. Results: Patients with homozygote PTM had significantly lower dabigatran peak concentration compared to patients with FVL or the control group (23 ± 4.2 vs. 152.3 ± 27.5 and 159.6 ± 63.08; p-value ≤ 0.05) There was no significant difference in dabigatran etexilate plasma levels between the heterozygote PTM group compared to patients with FVL or the control group (p = 0.29). There was no correlation between dabigatran peak concentration and delayed thrombus dissolution. Conclusions: Dabigatran peak concentration was stable in patients with heterozygote FVL and heterozygote PTM, but not in homozygote PTM, compared to controls. Genetic screening for thrombophilia in patients after CSVT may be useful to make patient tailored therapeutic decisions regarding oral anticoagulation and may decrease thrombotic events.

Large-scale genetic correlation scanning and causal association between deep vein thrombosis and human blood metabolites

Deep vein thrombosis (DVT) refers to the abnormal coagulation of blood in a deep vein. Recently, some studies have found that metabolites are related to the occurrence of DVT and may serve as new markers for the diagnosis of DVT. In this study, we used the GWAS summary dataset of blood metabolites and DVT to perform a large-scale genetic correlation scan of DVT and blood metabolites to explore the correlation between blood metabolites and DVT. We used GWAS summary data of DVT from the UK Biobank (UK Biobank fields: 20002) and GWAS summary data of blood metabolites from a previously published study (including 529 metabolites in plasma or serum from 7824 adults from two European population studies) for genetic correlation analysis. Then, we conducted a causal study between the screened blood metabolites and DVT by Mendelian randomization (MR) analysis. In the first stage, genetic correlation analysis identified 9 blood metabolites that demonstrated a suggestive association with DVT. These metabolites included Valine (correlation coefficient = 0.2440, P value = 0.0430), Carnitine (correlation coefficient = 0.1574, P value = 0.0146), Hydroxytryptophan (correlation coefficient = 0.2376, P value = 0.0360), and 1-stearoylglycerophosphoethanolamine (correlation coefficient = - 0.3850, P value = 0.0258). Then, based on the IVW MR model, we analysed the causal relationship between the screened blood metabolites and DVT and found that there was a suggestive causal relationship between Hydroxytryptophan (exposure) and DVT (outcome) (β = - 0.0378, se = 0.0163, P = 0.0204). Our study identified a set of candidate blood metabolites that showed a suggestive association with DVT. We hope that our findings will provide new insights into the pathogenesis and diagnosis of DVT in the future.

Pathophysiology of deep vein thrombosis

Deep venous thrombosis is a frequent, multifactorial disease and a leading cause of morbidity and mortality. Most of the time deep venous thrombosis is triggered by the interaction between acquired risk factors, such as hip fracture, pregnancy, and immobility, and hereditary risk factors such as thrombophilias. The mechanisms underlying deep venous thrombosis are not fully elucidated; however, in recent years, important advances have shed light on the role of venous flow, endothelium, platelets, leukocytes, and the interaction between inflammation and hemostasis. It has been described that the alteration of venous blood flow produces endothelial activation, favoring the adhesion of platelets and leukocytes, which, through tissue factor expression and neutrophil extracellular traps formation, contribute to the activation of coagulation, trapping more cells, such as red blood cells. Thus, the concerted interaction of these phenomena allows the formation and growth of the thrombus. In this work, the main mechanisms involved in the pathophysiology of deep vein thrombosis will be described.

Classic Thrombophilias and Thrombotic Risk Among Middle-Aged and Older Adults: A Population-Based Cohort Study

Background

Five classic thrombophilias have been recognized: factor V Leiden (rs6025), the prothrombin G20210A variant (rs1799963), and protein C, protein S, and antithrombin deficiencies. This study aimed to determine the thrombotic risk of classic thrombophilias in a cohort of middle‐aged and older adults.

Methods and Results

Factor V Leiden, prothrombin G20210A and protein‐coding variants in the PROC (protein C), PROS1 (protein S), and SERPINC1 (antithrombin) anticoagulant genes were determined in 29 387 subjects (born 1923–1950, 60% women) who participated in the Malmö Diet and Cancer study (1991–1996). The Human Gene Mutation Database was used to define 68 disease‐causing mutations. Patients were followed up from baseline until the first event of venous thromboembolism (VTE), death, or Dec 31, 2018. Carriership (n=908, 3.1%) for disease‐causing mutations in the PROC, PROS1, and SERPINC1 genes was associated with incident VTE: Hazard ratio (HR) was 1.6 (95% CI, 1.3–1.9). Variants not in Human Gene Mutation Database were not linked to VTE (HR, 1.1; 95% CI, 0.8–1.5). Heterozygosity for rs6025 and rs1799963 was associated with incident VTE: HR, 1.8 (95% CI, 1.6–2.0) and HR, 1.6 (95% CI, 1.3–2.0), respectively. The HR for carrying 1 classical thrombophilia variant was 1.7 (95% CI, 1.6–1.9). HR was 3.9 (95% CI, 3.1–5.0) for carriers of ≥2 thrombophilia variants.

Conclusions

The 5 classic thrombophilias are associated with a dose‐graded risk of VTE in middle‐aged and older adults. Disease‐causing variants in the PROC, PROS1, and SERPINC1 genes were more common than the rs1799963 variant but the conferred genetic risk was comparable with the rs6025 and rs1799963 variants.

Large-scale correlation analysis of deep venous thrombosis and gut microbiota

Objective

Although previous studies have shown that gut microbiota may be involved in the occurrence of deep venous thrombosis (DVT), the specific link between the two remains unclear. The present study aimed to explore this question from a genetic perspective.

Materials and methods

Genome-wide association study (GWAS) summary data of DVT were obtained from the UK Biobank (N = 9,059). GWAS summary data of the gut microbiota were obtained from the Flemish Gut Flora Project (N = 2,223) and two German cohorts (FoCus, N = 950; PopGen, N = 717). All the participants were of European ancestry. Linkage disequilibrium score (LDSC) regression has great potential for analyzing the heritability of disease or character traits. LDSC regression was used to analyze the genetic correlation between DVT and the gut microbiota based on the GWAS summary data obtained from previous studies. Mendelian randomization (MR) was used to analyze the genetic causal relationship between DVT and the gut microbiota. We used the random effects inverse variance weighted, MR Egger, weighted median, simple mode, and weighted mode to perform MR analysis. We performed a sensitivity analysis of the MR analysis results by examining heterogeneity and horizontal pleiotropy.

Results

Linkage disequilibrium score analysis showed that Streptococcaceae (correlation coefficient = -0.542, SE = 0.237, P = 0.022), Dialister (correlation coefficient = -0.623, SE = 0.316, P = 0.049), Streptococcus (correlation coefficient = -0.576, SE = 0.264, P = 0.029), and Lactobacillales (correlation coefficient = -0.484, SE = 0.237, P = 0.042) had suggestive genetic correlation with DVT. In addition, the MR analysis showed that Streptococcaceae had a positive genetic causal relationship with DVT (P = 0.027, OR = 1.005). There was no heterogeneity or horizontal pleiotropy in the MR analysis (P > 0.05).

Conclusion

In this study, four gut microbes (Streptococcaceae, Dialister Streptococcus, Lactobacillales) had suggestive genetic correlations with DVT, and Streptococcaceae had a positive causal relationship with DVT. Our findings provide a new research direction for the further study of and prevention of DVT.

MEDTEC Students against Coronavirus: Investigating the Role of Hemostatic Genes in the Predisposition to COVID-19 Severity

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiologic agent of the coronavirus disease 2019 (COVID-19) pandemic. Besides virus intrinsic characteristics, the host genetic makeup is predicted to account for the extreme clinical heterogeneity of the disease, which is characterized, among other manifestations, by a derangement of hemostasis associated with thromboembolic events. To date, large-scale studies confirmed that genetic predisposition plays a role in COVID-19 severity, pinpointing several susceptibility genes, often characterized by immunologic functions. With these premises, we performed an association study of common variants in 32 hemostatic genes with COVID-19 severity. We investigated 49,845 single-nucleotide polymorphism in a cohort of 332 Italian severe COVID-19 patients and 1668 controls from the general population. The study was conducted engaging a class of students attending the second year of the MEDTEC school (a six-year program, held in collaboration between Humanitas University and the Politecnico of Milan, allowing students to gain an MD in Medicine and a Bachelor’s Degree in Biomedical Engineering). Thanks to their willingness to participate in the fight against the pandemic, we evidenced several suggestive hits (p < 0.001), involving the PROC, MTHFR, MTR, ADAMTS13, and THBS2 genes (top signal in PROC: chr2:127192625:G:A, OR = 2.23, 95%CI = 1.50–3.34, p = 8.77 × 10⁻⁵). The top signals in PROC, MTHFR, MTR, ADAMTS13 were instrumental for the construction of a polygenic risk score, whose distribution was significantly different between cases and controls (p = 1.62 × 10⁻⁸ for difference in median levels). Finally, a meta-analysis performed using data from the Regeneron database confirmed the contribution of the MTHFR variant chr1:11753033:G:A to the predisposition to severe COVID-19 (pooled OR = 1.21, 95%CI = 1.09–1.33, p = 4.34 × 10⁻¹⁴ in the weighted analysis).

Role of ADAMTS13, VWF and F8 genes in deep vein thrombosis

Background

We previously described the association between rare ADAMTS13 single nucleotide variants (SNVs) and deep vein thrombosis (DVT). Moreover, DVT patients with at least one rare ADAMTS13 SNV had a lower ADAMTS13 activity than non-carriers.

Aims

To confirm ADAMTS13 variants association with DVT and reduced plasma ADAMTS13 activity levels in a larger population. To investigate the role of VWF and F8 variants.

Methods

ADAMTS13, VWF and F8 were sequenced using next-generation sequencing in 594 Italian DVT patients and 571 controls. Genetic association testing was performed using logistic regression and gene-based tests. The association between rare ADAMTS13 variants and the respective plasmatic activity, available for 365 cases and 292 controls, was determined using linear regression. All analyses were age-, sex- adjusted.

Results

We identified 48 low-frequency/common and 272 rare variants. Nine low-frequency/common variants had a P<0.05, but a false discovery rate between 0.06 and 0.24. Of them, 7 were found in ADAMTS13 (rs28641026, rs28503257, rs685523, rs3124768, rs3118667, rs739469, rs3124767; all protective) and 2 in VWF (rs1800382 [risk], rs7962217 [protective]). Rare ADAMTS13 variants were significantly associated with DVT using the burden, variable threshold (VT) and UNIQ (P<0.05), but not with C-ALPHA, SKAT and SKAT-O tests. Rare VWF and F8 variants were not associated with DVT. Carriers of rare ADAMTS13 variants had lower ADAMTS13 activity than non-carriers (ß -6.2, 95%CI -11,-1.5). This association was stronger for DVT patients than controls (ß -7.5, 95%CI -13.5,-1.5 vs. ß -2.9, 95%CI -10.4,4.5).

Conclusions

ADAMTS13 and VWF low-frequency/common variants mainly showed a protective effect, although their association with DVT was not confirmed. DVT patients carrying a rare ADAMTS13 variants had slightly reduced ADAMTS13 activity levels, but a higher DVT risk. Rare VWF and FVIII variants were not associated with DVT suggesting that other mechanisms are responsible for the high VWF and FVIII levels measured in DVT patients.

Two-point compression ultrasonography: Enough to rule out lower extremity deep venous thrombosis?

BACKGROUND

Deep venous thrombosis (DVT) is a major cause of morbidity and is a common presenting complaint to the emergency department (ED). Point-of-care two-point compression ultrasonography has evolved as a quick and effective way of diagnosing DVT. The purpose of this study is to validate the prevalence and distribution of venous thrombi isolated to proximal lower extremity veins, other than common femoral and popliteal veins in patients with DVT.

METHODS

This is a single-center retrospective study that looked at patients presenting to the ED of a tertiary care hospital between January 2014 and August 2018. The clinical presentation and laboratory and imaging results were obtained using the hospital's electronic medical record.

RESULTS

A total of 2,507 patients underwent a lower extremity duplex ultrasound during the study period. Among them, 379 (15%) were included in the study. The percentages of isolated thrombi to the femoral vein and deep femoral vein were 7.92% and 0.53%, respectively. When the patients were stratified into the two groups of isolated DVT and two-point compression DVT, there were no statistically significant differences in the laboratory results between both groups. However, immobilized patients and patients with recent surgeries were more likely to have an isolated DVT.

CONCLUSIONS

Thrombi isolated to proximal lower extremity veins other than the common femoral and popliteal veins make up 8.45% of DVTs. Given this significant number of missed DVTs, the authors recommend the addition of the femoral and deep femoral veins to the two-point compression exam.

A review on clotting disorders and retinal hemorrhages: Can they mimic abuse?

BACKGROUND

The characteristic findings of abusive head trauma (AHT) include retinal hemorrhages (RH). RH have many etiologies in childhood, which should be considered in the differential diagnosis of possible child abuse. The relationship between RH and thrombophilia in children is not well established.

OBJECTIVE

In this literature review, we sought to assess whether retinal findings in pediatric patients with thrombophilia could mimic those of AHT.

METHODS

A literature search was performed to identify all cases of thrombophilia in children less than 18 years old with ocular manifestations. Disorders of thrombophilia including protein C and S deficiency, factor V Leiden (FVL), prothrombin variant, MTHFR mutation, hyperhomocysteinemia, elevated factor VIII, and elevated lipoprotein (a) were considered. All cases of pediatric thrombophilia with retinal examination or intraocular bleeding were included. If provided, descriptions of the RH were reviewed.

RESULTS

Our initial search yielded 514 results. Forty-three articles met our inclusion criteria. We identified 3 children with RH within the AHT usual age range (<5 years old), ages 5 weeks and 7 weeks old, in the setting of thrombophilia. One child had ocular findings that could potentially mimic abuse. No other indicators of abuse were present in this case.

CONCLUSIONS

Based on previous reports, thrombophilia alone has not been shown to clearly mimic abusive head trauma. In reported cases of thrombophilia with RH, the clinical picture and ophthalmic findings are usually distinct from abuse.

Genetic Risk Profiling Associated with Recurrent Unprovoked Venous Thromboembolism

INTRODUCTION

Venous thromboembolism (VTE), including deep vein thrombosis (DVT) and/or pulmonary embolism (PE), is a common, acute, multifactorial disease with a five-years cumulative incidence of recurrence of approximately 25%. Actually, no single genetic defect can predict the risk of recurrence of VTE. Therefore, individual genetic risk profiling could be useful for the prediction of VTE recurrence.

AIM OF THE STUDY

To assess the combined effect of the common prothrombotic genotypes on the risk of recurrence of VTE in recently diagnosed unprovoked VTE patients.

PATIENTS AND METHODS

This population based, prospective follow-up study was carried out from January 2015 to December 2020 in (internal medicine, cardiovascular medicine and anesthesia and ICU departments, Tanta University Hospital, Egypt) on 224 recently diagnosed unprovoked VTE patients. Whole blood was collected by standard venipuncture at the time of admission prior to the beginning of anticoagulant therapy. Genomic DNA was extracted and was genotyped for the 5-SNPs Genetic risk score (GRS), previously validated for first venous thrombosis (FVL rs6025, PTM rs1799963, ABO rs8176719, FGG rs2066865 and FXI rs2036914).

RESULTS

The main important finding in the present study was that patients having ≥3 risk alleles were associated with higher risk of VTE recurrence compared to those having ≤2 risk alleles (the reference group) (HR 2.5, 95% CI 1.48-4.21) (p = 0.001). Patients with GRS ≥ 3 had a significantly shorter time recurrence free survival (43.07 months) compared to the low risk group of patients with GRS (0-2) (p < 0.001).

CONCLUSION

GRS model could be an effective and useful model in risk stratification of VTE patients, and genetic risk profiling of VTE patients could be used for the prediction of recurrence of VTE.

Single- and Multimarker Genome-Wide Scans Evidence Novel Genetic Risk Modifiers for Venous Thromboembolism

Previous genome-wide association studies (GWASs) have established several susceptibility genes for venous thromboembolism (VTE) and suggested many others. However, a large proportion of the genetic variance in VTE remains unexplained. Here, we report genome-wide single- and multimarker as well as gene-level associations with VTE in 964 cases and 899 healthy controls of European ancestry. We report 19 loci at the genome-wide level of association (p ≤ 5 × 10^-8). Our results add to the strong support for the association of genetic variants in F5, NME7, ABO, and FGA with VTE, and identify several loci that have not been previously associated with VTE. Altogether, our novel findings suggest that 20 susceptibility genes for VTE were newly discovered by our study. These genes may impact the production and prothrombotic functions of platelets, endothelial cells, and white and red blood cells. Moreover, the majority of these genes have been previously associated with cardiovascular diseases and/or risk factors for VTE. Future studies are warranted to validate our findings and to investigate the shared genetic architecture with susceptibility factors for other cardiovascular diseases impacting VTE risk.

Direct oral anticoagulants for therapeutic anticoagulation in postoperative pulmonary embolism after meningioma resection

BACKGROUND

Acute postoperative pulmonary embolism (PE) is a dreaded complication with severe mortality rates. Brain tumor patients are at the highest risk for postoperative PE. The juxtaposition of low-molecular-weight heparin (LMWH), vitamin K antagonists (VKA) and direct oral anticoagulation (DOAC) in the treatment of postoperative PE in meningioma patients is largely unexplored.

PATIENTS/METHODS

This is a single center observational analysis of meningioma patients who underwent neurosurgical resection with a thoracic CT scan confirmation of postoperative PE. The treatment modality, clinical course and outcome were investigated.

RESULTS

Of 538 meningioma patients operated, 30 (6%) developed acute postoperative PE. After diagnosis, these patients received different long-term anticoagulation regimes. No significant difference in postoperative hemorrhage (p < 0.56), re-operation rate (p < 0.70) or Karnofsky performance scale (KPS) at 3 (p < 0.34) and 12 months (p = 1) were identified, when compared according to the different anticoagulation regimes.

CONCLUSION

DOACs were not associated with elevated risk for hemorrhage, recurrent thrombosis or poor outcome when compared with traditional anticoagulation regimes. Prospective randomized trials are necessary to verify the non-inferiority of DOACs for long-term anticoagulation in postoperative pulmonary embolism after meningioma resection.

Three-factorial Genetic Thrombophilia with Recurrent Thrombotic Events in a Saudi Patient: A Case Report

Thrombophilia is caused by several genetic and acquired factors. Existence of more than one genetic factor may increase the risk of developing recurrent thrombotic events. Here, we present a case of a 48-year-old male with a known history of deep venous thrombosis and a known mutation in factor V Leiden combined with mild protein S deficiency, who presented with a painful swelling in the left leg. Moreover, the patient had a history of diabetes, dyslipidemia and obesity. Prothrombin time and platelet count were within the normal range. The international normalized ratio and activated partial thromboplastin time were 3.21 and 36.7 s, respectively. The Doppler study showed a thrombus in the saphenous vein, and complementary genetic screening investigations revealed heterozygous mutation for prothrombin (G20210A). A diagnosis of multifactorial genetic thrombophilia was established. The patient was treated with warfarin, which resulted in significant improvement in the follow-ups, and at the time of reporting this case, there were no clinical or biological signs of thrombosis. The presence of multiple hereditary and acquired thrombophilic factors is a rare clinical presentation that requires close monitoring, for which a lifelong anticoagulation therapy should be discussed based on the clinical response of the patient.

Thrombus stability explains the factor V Leiden paradox: a mouse model

Humans carrying the factor V Leiden (FVL) variant have a fivefold increased risk for venous thrombosis. However, incidence of deep vein thrombosis (DVT) is proportionally greater than that of pulmonary embolism (PE) in these individuals. This is known as the FVL paradox. We hypothesized that the rate of initial DVT development is similar in FVL and noncarriers, but thrombi in FVL carriers are more stable and develop into a clinically significant DVT more often than in noncarriers. To test this, we induced thrombi in the femoral vein of wild-type (WT), heterozygous (F5L/+), and FVL homozygous (F5L/L) mice. Using intravital microscopy, thrombus size and embolization were visualized and emboli in the lungs were quantified. Compared with WT, femoral vein thrombi in F5L/+ and F5L/L mice were larger and embolized less. Total and large embolic events, the percentage of thrombus that embolized, and PE burden were significantly decreased in F5L/L mice. This suggests that in noncarriers (reflected by WT), a minor injury initially resulting in a small DVT tends to remain small and asymptomatic because of the embolization of the otherwise growing thrombus. Alternatively, the same insult in people with FVL (reflected by F5L/L) leads to thrombus growth as a result of less embolization, and thus symptomatic DVT development.

The Silence Speaks, but We Do Not Listen: Synonymous c.1824C>T Gene Variant in the Last Exon of the Prothrombin Gene as a New Prothrombotic Risk Factor

BACKGROUND

Thrombosis is a major global disease burden with almost 60% of cases related to underlying heredity and most cases still idiopathic. Synonymous single nucleotide polymorphisms (sSNPs) are considered silent and phenotypically neutral. Our previous study revealed a novel synonymous FII c.1824C>T variant as a potential risk factor for pregnancy loss, but it has not yet been associated with thrombotic diseases.

METHODS

To determine the frequency of the FII c.1824C>T variant we have sequenced patients' DNA. Prothrombin RNA expression was measured by quantitative PCR. Functional analyses included routine hemostasis tests, western blotting and ELISA to determine prothrombin levels in plasma, and global hemostasis assays for thrombin and fibrin generation in carriers of the FII c.1824C>T variant. Scanning electron microscopy was used to examine the structure of fibrin clots.

RESULTS

Frequency of the FII c.1824C>T variant was significantly increased in patients with venous thromboembolism and cerebrovascular insult. Examination in vitro demonstrated increased expression of prothrombin mRNA in FII c.1824T transfected cells. Our ex vivo study of FII c.1824C>T carriers showed that the presence of this variant was associated with hyperprothrombinemia, hypofibrinolysis, and formation of densely packed fibrin clots resistant to fibrinolysis.

CONCLUSION

Our data indicate that FII c.1824C>T, although a synonymous variant, leads to the development of a prothrombotic phenotype and could represent a new prothrombotic risk factor. As a silent variant, FII c.1824C>T would probably be overlooked during genetic screening, and our results show that it could not be detected in routine laboratory tests.

The genetics of venous thromboembolism: a systematic review of thrombophilia families

Genetic risk factors are important for the occurrence and prognosis of venous thromboembolism (VTE). The studies of thrombophilia families are important for dissecting the genetic background of the thrombotic disease. We conducted the systematic review of all published family-based studies on VTE genetics across all racial groups through PubMed and Embase prior to 13th April 2020. This systematic review of 287 families (including 225 Caucasian families, 52 East Asian families, and families of other ethnicities) revealed a total of 21 different genes; the five most reported mutated genes were F5 (88/287, 30.7%), SERPINC1 (67/287, 23.3%), PROC (65/287, 22.6%), F2 (40/287, 13.9%) and PROS1 (48/287, 16.7%). For Caucasian families, F5 mutations were most frequently reported at 37.8% (85/225), while PROS1 mutations were most frequently reported, at 40.4% (21/52), for East Asian families (Chinese, Japanese and Korean). Factor V Leiden was reported more frequently in Caucasians than in East Asians. Missense mutations were reported frequently in the SERPINC1, PROC and PROS1 genes. In conclusion, our study found the most likely mutated genes associated with VTE among different ethnic groups and provided indications for VTE genetic testing and research in the future.

Clinical Predictive Factors of Lower Extremity Deep Vein Thrombosis in Relative High-Risk Patients after Neurosurgery: A Retrospective Study

INTRODUCTION

It is acknowledged that patients undergoing neurosurgery with neurological illness are at higher risk of lower extremity deep vein thrombosis (DVT). As an underlying life-threatening complication, the incidence and risk factors for high-risk patients with lower extremity deep vein thrombosis are still controversial in relative high-risk patients after neurosurgery.

MATERIALS AND METHODS

A total of 204 patients who underwent neurosurgery and were considered as a high-risk group of DVT according to times of stay in bed more than 3 days were enrolled in this study. We evaluated the lower extremity DVT by using Color Doppler Ultrasound System (CDUS). Clinical parameters of patients at the time of admission and postoperation were recorded and prepared for further analysis. Early predictive factors for postoperative lower extremity DVT were established. Diagnostic performance of predictive factors was evaluated by using receiver operating characteristic (ROC) curve analysis.

RESULTS

The overall incidence rate of DVT in 204 enrolled patients was 30.9%. Multivariate logistic regression indicated that hypertension (OR 3.159, 95% CI 1.465-6.816; P = 0.003), higher postoperative D-dimer (OR 1.225, 95% CI 1.016-1.477; P = 0.034), female (OR 0.174, 95% CI 0.054-0.568; P = 0.004), and lower GCS score (OR 0.809, 95% CI 0.679-0.965; P = 0.013) were independently associated with incidence of DVT in patients after neurosurgery. The logistic regression function (LR model) of these four independent risk factors had a better performance on diagnostic value of DVT in patients after neurosurgery.

CONCLUSION

The combined factor was constructed by hypertension, postoperative D-dimer, gender, and GCS score, and it might be a more handy and reliable marker to stratify patients at risk of DVT after neurosurgery.

Pulmonary embolism in neurocritical care-introduction of a novel grading system for risk stratification: the Frankfurt AMBOS score

Pulmonary embolism (PE) due to deep vein thrombosis is a complication with severe morbidity and mortality rates. Neurocritical care patients constitute an inhomogeneous cohort with often strict contraindications to conventional embolism treatment. The aim of the present study is to identify risk factors for pulmonary embolism for intensified risk stratification in this demanding cohort. In this retrospective analysis, 387 neurocritical care patients received computed tomography for clinical suspicion of PE (304 neurosurgical and 83 neurological patients). Analysed parameters included age, gender, disease pattern, the presence of deep vein thrombosis, resuscitation, in-hospital mortality, present anticoagulation, coronary artery disease, diabetes mellitus, smoking status, hypertension and ABO blood type. Computed tomography confirmed 165 cases of pulmonary embolism among 387 patients with clinical suspicion of pulmonary embolism (42%). Younger age (p < 0.0001), female gender (p < 0.006), neurooncological disease (p < 0.002), non-O blood type (p < 0.002) and the absence of Marcumar therapy (p < 0.003) were identified as significant risk factors for pulmonary embolism. On the basis of the identified risk factors, the AMBOS score system is introduced. Neurocritical care patients with high AMBOS score are at elevated risk for PE and should therefore be put under intensified monitoring for cardiovascular events in neurocritical care units.

Principal Component Analysis on Recurrent Venous Thromboembolism

The rates of recurrent venous thromboembolism (RVTE) vary widely, and its causes still need to be elucidated. Statistical multivariate methods can be used to determine disease predictors and improve current methods for risk calculation. The objective of this study was to apply principal component analysis to a set of data containing clinical records of patients with previous venous thromboembolism and extract the main factors that predict recurrent thrombosis. Records of 39 factors including blood and lipid parameters, hereditary thrombophilia, antiphospholipid syndrome, clinical data regarding previous thrombosis and treatment, and Doppler ultrasound results were collected from 235 patients. The results showed that 13 principal components were associated with RVTE and that 18 of 39 factors are the important for the analysis. These factors include red blood cell, white blood cell, hematocrit, red cell distribution width, glucose, lipids, natural anticoagulant, creatinine, age, as well as first deep vein thrombosis data (distal/proximal, d-dimer, and time of anticoagulation). The results demonstrated that simple clinical parameters easy to be collected can be used to predict rates of recurrence and to develop new clinical decision support systems to predict the rates of RVTE.

The joint effect of genetic risk factors and different types of combined oral contraceptives on venous thrombosis risk

It is not known whether the synergistic effect of genetic markers, increasing the risk of venous thrombosis (VT), and combined oral contraceptives (COC) use varies between different types of progestogens in these preparations. We investigated the joint effect of genetic risk factor, that is, F5 rs6025, F2 rs1799963, and FGG rs2066865 mutations, and different progestogens on the risk of VT. The constrained maximum likelihood estimation (CMLE) method was used to calculate joint effects, expressed as odds ratio (OR) with 95% confidence intervals [CI]. As the dose of estrogen is known to be a risk factor for VT, analyses were restricted to COC with 30 µg estrogen and each progestogen. Overall, the joint effect of COC and genetic variants was lowest for COC containing the progestogen levonorgestrel, albeit CIs were wide. The OR (95% CI) of the four different analyses (i.e. joint effect with F5 rs6025, F2 rs1799963, F5 rs6025 or F2 rs1799963 and FGG rs2066865) ranged between 7·4 (5·4–10·2) and 24·8 (12·3–50·0) for levonorgestrel. For gestodene the joint effect ranged between 11·7 (7·2–19·1) and 30·9 (10·6–89·9). Desogestrel and cyproterone acetate had the highest risk estimates: 14·6 (9·7–21·9) and 32·6 (13·2–80·6) and 15·5 (9·7–24·9) and 44·4 (16·9–116·3) respectively. In women with inherited thrombophilia, COC containing levonorgestrel were associated with the lowest risk of VT, albeit the CIs were wide.

Activated αIIbβ3 on platelets mediates flow-dependent NETosis via SLC44A2

Platelet-neutrophil interactions are important for innate immunity, but also contribute to the pathogenesis of deep vein thrombosis, myocardial infarction and stroke. Here we report that, under flow, von Willebrand factor/glycoprotein Ibα-dependent platelet 'priming' induces integrin αIIbβ3 activation that, in turn, mediates neutrophil and T-cell binding. Binding of platelet αIIbβ3 to SLC44A2 on neutrophils leads to mechanosensitive-dependent production of highly prothrombotic neutrophil extracellular traps. A polymorphism in SLC44A2 (rs2288904-A) present in 22% of the population causes an R154Q substitution in an extracellular loop of SLC44A2 that is protective against venous thrombosis results in severely impaired binding to both activated αIIbβ3 and VWF-primed platelets. This was confirmed using neutrophils homozygous for the SLC44A2 R154Q polymorphism. Taken together, these data reveal a previously unreported mode of platelet-neutrophil crosstalk, mechanosensitive NET production, and provide mechanistic insight into the protective effect of the SLC44A2 rs2288904-A polymorphism in venous thrombosis.

Molecular Analysis of Prothrombotic Gene Variants in Venous Thrombosis: A Potential Role for Sex and Thrombotic Localization

Background: Requests to test for thrombophilia in the clinical context are often not evidence-based. Aim: To define the role of a series of prothrombotic gene variants in a large population of patients with different venous thromboembolic diseases. Methods: We studied Factor V Leiden (FVL), FVR2, FII G20210A, Methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C, beta-fibrinogen -455 G>A, FXIII V34L, and HPA-1 L33P variants and PAI-1 4G/5G alleles in 343 male and female patients with deep vein thrombosis (DVT), 164 with pulmonary embolism (PE), 126 with superficial vein thrombosis (SVT), 118 with portal vein thrombosis (PVT), 75 with cerebral vein thrombosis (CVT) and 119 with retinal vein thrombosis (RVT), and compared them with the corresponding variants and alleles in 430 subjects from the general population. Results: About 40% of patients with DVT, PE and SVT had at least one prothrombotic gene variant, such as FVL, FVR2 and FII G20210A, and a statistically significant association with the event was found in males with a history of PE. In patients with a history of PVT or CVT, the FII G20210A variant was more frequent, particularly in females. In contrast, a poor association was found between RVT and prothrombotic risk factors, confirming that local vascular factors have a key role in this thrombotic event. Conclusions: Only FVL, FVR2 and FII G20210A are related to vein thrombotic disease. Other gene variants, often requested for testing in the clinical context, do not differ significantly between cases and controls. Evidence of a sex difference for some variants, once confirmed in larger populations, may help to promote sex-specific prevention of such diseases.

Targeted gene expression study using TaqMan low density array to gain insights into venous thrombo-embolism (VTE) pathogenesis at high altitude

Venous thrombo-embolism (VTE) is multi-factorial disease involving several genetic and acquired risk factors responsible for its onset. It may occur spontaneously upon climbing at High Altitude (HA). Several studies demonstrated that hypoxic conditions prevailing at HA pose an independent risk factor for VTE; however, molecular mechanism remains unknown. Present study aims to identify genes associated with HA-induced VTE pathophysiology using real time TaqMan Low-Density Array (TLDA) of known candidate genes. Gene expression of total 93 genes were studied and analyzed in patients of VTE from HA (HA-VTE) and from sea level (SL-VTE) in comparison to respective controls. Both HA-VTE and SL-VTE patients showed up-regulation of 37 genes involved in blood coagulation cascade, clot formation, platelet formation, endothelial response, angiogenesis, cell adhesion and calcium channel activity. Seven genes including ACE, EREG, C8A, DLG2, USF1, F2 and PCDHA7 were up-regulated in both HA-controls and VTE patients (both HA-VTE and SL-VTE) indicating their role during VTE event and also upon HA exposure. Ten genes; CDH18, FGA, EDNBR, GATA2, MAPK9, BCAR1, FRK, F11, PCDHA1 and ST8SIA4 were uniquely up-regulated in HA-VTE. The differentially expressed genes from the present study could be determining factors for HA-VTE susceptibility and provide insights into VTE occurrence at HA.

Prevalence of pulmonary thromboembolism in nephrotic syndrome patients: A systematic review and meta-analysis

This study was aimed to assess the prevalence of pulmonary thromboembolism in patients with nephrotic syndrome. An electronic search was conducted through nine electronic databases for selection of relevant articles reporting the prevalence of pulmonary thromboembolism in patients with nephrotic syndrome. National Institute of Health was used to assess the quality of each study. Meta-analysis was used to pool the results. Of total 2267 reports screened, we finally included 11 studies including five retrospective cohorts, four prospective cohorts, and two case series studies. Out of these, ten articles were eligible for meta-analysis. The overall prevalence was 7.93% with 95% CI of 4.27 to 14.73. However, a significant heterogeneity (P < 0.001) was observed with I2= 96% and τ2= 0.899. Moreover, Egger's regression test showed a significant risk of bias (P = 0.006). Patients with nephrotic syndrome are prone to pulmonary embolism, therefore early management is critical to decreasing mortality burden.

Electrochemical Detection of Solution Phase Hybridization Related to Single Nucleotide Mutation by Carbon Nanofibers Enriched Electrodes

In the present study, a sensitive and selective impedimetric detection of solution-phase nucleic acid hybridization related to Factor V Leiden (FV Leiden) mutation was performed by carbon nanofibers (CNF) modified screen printed electrodes (SPE). The microscopic and electrochemical characterization of CNF-SPEs was explored in comparison to the unmodified electrodes. Since the FV Leiden mutation is a widespread inherited risk factor predisposing to venous thromboembolism, this study herein aimed to perform the impedimetric detection of FV Leiden mutation by a zip nucleic acid (ZNA) probe-based assay in combination with CNF-SPEs. The selectivity of the assay was then examined against the mutation-free DNA sequences as well as the synthetic PCR samples.

Pathogenic variants of PROC gene caused type I activity deficiency in a familial Chinese venous thrombosis

Pathogenic mutation of protein C (PROC) gene results into the deficiency of PROC activity. This study aimed to identify the pathogenic genetic variants and to explore the functional consequence in Chinese familial venous thrombosis (VTE). Whole exome sequencing was performed to identify the pathogenic variants of anticoagulant factors. Serum coagulation and anti-coagulation factors activity were assayed to evaluate the genetic association. Functional study of PROC antigen secretion deficiency was conducted in VTE subjects and in vitro cell lines. One rare pathogenic variant (p.Ala178Pro) was identified in the four VTE subjects but not in the normal subjects from the family. An inframeshift variant (rs199469469) was also identified in a paediatric subject of the pedigree. Further evaluation of serum PROC activity levels in p.Ala178Pro variants VTE carriers showed significantly lower PROC activity compared to non-carriers. Furthermore, in vitro study showed that the p.Ala178Pro mutant cells had a consistent reduction in concentration of PROC antigen. In conclusions, our study demonstrated the pathogenic variant (p.Ala178Pro) contributed to PROC type I activity deficiency, which may be due to decreased secretion of PROC.

Association of SERPINC1 Gene Polymorphism (rs2227589) With Pulmonary Embolism Risk in a Chinese Population

Background and Aims: Genetic variants in the gene SERPINC1 have been shown to be associated with antithrombin deficiency, which subsequently contributes to the susceptibility to venous thrombosis. However, several other studies have shown conflicting results regarding the association of SERPINC1 gene polymorphisms (rs2227589) with the risk of thrombosis. Hence, in the present study, we conducted a case-control study to further evaluate the association between the variant rs2227589 with antithrombin deficiency in pulmonary embolism (PTE). A pooled systematic analysis was also conducted to evaluate the risk of rs2227589 in venous thromboembolism (VTE) among multiple populations. Methods: This case-control study involved 101 patients and 199 healthy controls. The allele frequency of SERPINC1 variant rs2227589 was analyzed by Sequenom assay. Antithrombin anticoagulant activity was detected using an automatic coagulation analyzer. In addition, a pooled systematic analysis on 10 cohorts consisting of 5,518 patients with VTE and 8,935 controls was performed. Results: In total, 27 (26.7%) PTE subjects were diagnosed as having antithrombin deficiency. Our results showed that antithrombin plasma activity was slightly lower in T allele carriers than that in C allele carriers. However, there was no significant correlation between rs2227589 genotype and antithrombin anticoagulant activity. The recessive model showed that rs2227589 was significantly associated (p = 0.026) with an increased risk {odds ratio [OR]: 2.31, 95% confidence interval [CI] (1.09-4.89)} of Chinese PTE. The pooled systematic analysis of all case-control study and meta-analysis showed that rs2227589 polymorphism was associated with an increased risk of VTE in the additive model [OR: 1.09, 95% CI (1.01-1.18), P = 0.029] and dominant model [OR: 1.10, 95% CI (1.01-1.20), P = 0.034]. Conclusions: Our study demonstrated that variant rs2227589 is associated with an increased risk of PTE in a Chinese population but no correlation with antithrombin anticoagulant activity. However, pooled systematic analysis of multiple populations showed a significant association between rs2227589 and the risk of VTE in the additive and dominant genetic model.

Evaluation of Factor V Leiden and prothrombin G20210A mutations in Sudanese women with severe preeclampsia

BACKGROUND

Preeclampsia (PE) is a common pregnancy complication and one of the main causes of maternal and fetal morbidity and mortality, worldwide. While the pathogenesis of PE is unclear, it has been suggested that hypercoagulability due to Factor V Leiden (FVL) and prothrombin gene mutation (FII G20210A) play a role in its progression.

PURPOSE

This study aimed to determine if there is an association between FVL and FII G20210A mutations and severe PE.

PATIENTS AND METHODS

This case-control study enrolled 50 women with severe PE and 50 healthy pregnant women as the control, at Khartoum North Teaching Hospital, in Khartoum State, Sudan, from January 2017 to June 2017. The presence of point mutations in FVL and FII G20210A were determined for each of the participants. Deoxyribonucleic acid (DNA) was extracted, and then an allele-specific polymerase chain reaction (PCR) was used to detect the point mutations in FVL and FII G20210A.

RESULTS

The results revealed a significant difference between the subjects in the severe PE group and the control group for the means of parity, gestational age/ week and hemoglobin concentration (P < 0.05). No statistically significant body mass index (BMI) differences were found between the groups (P > 0.05). Women with severe PE were found to have a significant difference in FVL (16%; P value = 0.0058; OR: 20.20; 95%CI: 1.132-360.5) and FII G20210A (14%; P value = 0.0125; OR: 17.41; 95%CI: 0.9659-314.0) in comparison to the women in the control group (0%).

CONCLUSION

Our findings intensely indicate that there is a statistically proven significant association between FVL, FII G20210A mutations and the development of severe preeclampsia in Sudanese pregnant women.

Posterior reversible encephalopathy syndrome, preeclampsia or stroke? A diagnostic dilemma

When a pregnant woman presents with headaches, visual disturbances, epigastric pain and nausea, preeclampsia quickly springs to mind. This case describes a primigravid 22-year-old female of 32 weeks gestation who presented with the symptoms described but was found to be apparently normotensive. Due to ongoing symptoms and diagnostic uncertainty in the absence of definitive evidence of preeclampsia, the patient was further investigated with an MRI brain scan, which was reported as either an acute stroke or an atypical presentation of posterior reversible encephalopathy syndrome. Together with blood results that showed heterozygosity for Factor V Leiden, we concluded that while the patient's clinical diagnosis was certainly preeclampsia, her investigations also supported an unexpected diagnosis of silent brain infarction. This report outlines a diagnostic dilemma that required multidisciplinary working between obstetricians, neurologists, radiologists and stroke physicians to manage the patient who went on to make a full recovery and deliver a healthy baby.

The Impact of Multiple Risk Factors for Venous Thromboembolism and Its Implications for Management

Venous thromboembolism (VTE) is a rare multifactorial disorder in childhood with an annual incidence of about 0.07 to 0.14 per 10 000 children. A 15-year-old female with a body mass index of 48 kg/m² who endorsed oral contraceptive use presented with clinical findings consistent with deep venous thrombosis along with the presence of a pulmonary embolism. Further workup revealed that the patient was heterozygous for factor V Leiden and homozygous for prothrombin G20210A mutations. There are no current pediatric guidelines for the antithrombotic management of patients with multiple risk factors for VTE. Two such risk factors, obesity and the use of estrogen-containing hormone contraceptives, have been implicated in adult VTE cases but have not been clearly delineated in pediatric patients. The need for guidance regarding the VTE management of these patients has become more apparent given the increasing incidence of childhood obesity and the number of adolescents using oral contraceptives. Additionally, thrombophilia testing remains controversial though testing may be indicated in asymptomatic first-degree relatives and in families with antithrombin, protein C, or protein S deficiencies. Given the increased incidence of multiple risk factors for VTE, there is also a need to develop a comprehensive risk assessment tool for pediatric patients at high risk of VTE.

Predicting venous thromboembolism risk from exomes in the Critical Assessment of Genome Interpretation (CAGI) challenges

Genetics play a key role in venous thromboembolism (VTE) risk, however established risk factors in European populations do not translate to individuals of African descent because of the differences in allele frequencies between populations. As part of the fifth iteration of the Critical Assessment of Genome Interpretation, participants were asked to predict VTE status in exome data from African American subjects. Participants were provided with 103 unlabeled exomes from patients treated with warfarin for non-VTE causes or VTE and asked to predict which disease each subject had been treated for. Given the lack of training data, many participants opted to use unsupervised machine learning methods, clustering the exomes by variation in genes known to be associated with VTE. The best performing method using only VTE related genes achieved an area under the ROC curve of 0.65. Here, we discuss the range of methods used in the prediction of VTE from sequence data and explore some of the difficulties of conducting a challenge with known confounders. In addition, we show that an existing genetic risk score for VTE that was developed in European subjects works well in African Americans.

The relative roles of maternal survival and inter-personal violence as selection pressures on the persistence of Neanderthal hypercoagulability alleles in modern Europeans

Background: Simonti et al. reported variation in the frequency of Neanderthal alleles found in modern humans and argued that they may have provided an evolutionary advantage. One such allele is SNP rs3917862, associated with hypercoagulability. rs3917862 can be deleterious, but can also help prevent blood loss. Aim: To investigate two possible selective pressure hypotheses for rs3917862 surviving to higher frequencies: deaths from interpersonal violent trauma and childbirth. Subjects and methods: Mortality data from modern hunter-gatherers models the living conditions and causes of death of humans and Neanderthals at the point of admixture. Results: National census data indicates a positive correlation between the presence of rs3917862 and decreased maternal mortality ratios. When the maternal mortality ratio is modelled using GDP, births attended by skilled assistants and the presence of rs3917862, women are 0.1% more likely to die in childbirth in populations lacking rs3917862. Deaths due to violence show no correlation with rs3917862. Conclusion: These findings challenge the idea that Neanderthal admixture has negatively impacted the overall health of modern humans. Maternal survival may have acted as a selective pressure for the persistence of hypercoagulability alleles in modern Europeans. Understanding the role of hypercoagulability in childbirth, and the role of rs3917862, could help to reduce maternal mortality ratios.

Genetic polymorphisms associated with the prevalence of retinal vein occlusion in a Greek population

PURPOSE

To investigate possible associations of single-nucleotide polymorphisms (SNPs) from five genes with branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO).

METHODS

A total of 69 patients with retinal vein occlusion-RVO (24 with BRVO and 45 with CRVO), and 82 controls, were enrolled in this study. All subjects were screened for hypertension, diabetes mellitus, hyperlipidemia, glaucoma, anticoagulant medication, smoking status and history of stroke. The genotyping of AGTR1-A1166C, adiponectin + 276 G/T, MMP2-1306C/T, Gpla/lla-C807T/G873A and VKORC1-G1639A polymorphisms was performed using restriction fragment length polymorphism or allele-specific polymerase chain reaction.

RESULTS

The percentage of the AGTR1-A1166C C allele carriers and Gpla/lla-C807T/G873A T/A carriers was significantly higher in the CRVO patients than in the controls (P = 0.00001 and P = 0.0004, respectively). At the multiple logistic regression analysis, the AGTR1-A1166C C allele carrier status and the Gpla/lla-C807T/G873A T/A allele carrier status were found to be associated with an increased risk of CRVO. Moreover, adiponectin + 276 G/T T allele carriers had a significantly increased risk of RVO in subjects ≥ 75 years old. There was no significant difference between the BRVO patients and controls concerning the genotype or the allele frequency distributions of these SNPs. The genotype distributions or allelic frequencies of the other evaluated polymorphisms did not significantly differ between the patients with RVO and the control subjects.

CONCLUSIONS

AGTR1 A1166C and Gpla/lla C807T/G873A polymorphisms are likely to be risk factors for CRVO. Adiponectin + 276 G/T SNP is likely to predispose to RVO in older subjects.

ZNA probe immobilized single-use electrodes for impedimetric detection of nucleic acid hybridization related to single nucleotide mutation

The development of a low-cost and disposable biosensing technologies has received a great interest of healthcare for the sensitive and reliable detection of single nucleotide mutation related to single nucleotide polymorphisms (SNPs). In the present study, an impedimetric biosensing platform based on zip nucleic acids (ZNA) was developed for the sensitive detection of Factor V Leiden (FV Leiden) mutation. After optimization of experimental parameters, the sequence selective hybridization between ZNA probe and target related to FV Leiden mutation was evaluated via electrochemical impedance spectroscopy technique (EIS) by measuring changes at the charge transfer resistance, R_ct. Sensitive and selective impedimetric analysis was performed using carbon nanofiber (CNF) modified screen printed electrodes (SPE) and multi-channel screen printed array of electrodes (MULTIx8 CNF-SPE) resulting in a relatively shorter time in comparison to conventional methods. The selectivity of ZNA probe to mutation-free DNA sequences was also investigated. The applicability of single-use ZNA biosensor was also tested in synthetic PCR samples containing a single base mutation.

Magnetic beads assay based on Zip nucleic acid for electrochemical detection of Factor V Leiden mutation

Single nucleotide polymorphisms (SNPs) are the most common type of genetic variation among people. Development of reliable methods for the detection of SNP is crucial in aspects of molecular diagnosis and personalized medicine. In our study, a genomagnetic assay in combination with zip nucleic acid (ZNA) for electrochemical detection of SNP related to Factor V Leiden mutation. For the first time in the literature, a new generation nucleic acid; ZNA was applied herein for electrochemical monitoring of nucleic acid hybridization. Streptavidin coated magnetic beads (MBs) were used for preparation of samples containing ZNA-DNA hybrid and accordingly, the guanine signal was measured as a response of hybridization related to Factor V Leiden mutation by carbon nanofibers (CNF) modified screen printed electrodes (SPE) and multi-channel screen printed array of electrodes (CNF-MULTI SPEx8). The detection limit (DL) was found to be 3.79 μg/mL (376 nM) and, 11.63 μg/mL (1.624 μM), respectively by CNF-SPE and CNF-MULTI SPEx8. The selectivity of ZNA probe to mutation-free DNA sequences was also investigated in contrast to DNA probe. The applicability of ZNA based magnetic beads assay to sequence selective hybridization related to Factor V Leiden was also tested in synthetic PCR samples.

Dynamic changes of urinary proteins in a rat model of acute hypercoagulable state induced by tranexamic acid

The hypercoagulable state leads to the development of thrombotic diseases, but it is difficult to diagnose due to the lack of available biomarkers. This study aimed to investigate systematic changes of the urinary proteome in the acute hypercoagulable state. A rat model of the acute hypercoagulable state was induced by an antifibrinolytic agent tranexamic acid and urine samples were collected for proteomic analysis by liquid chromatography-tandem mass spectrometry. A total of 28 differential proteins were detected in the urinary proteome of the model rats, of which 12 had been previously considered as candidate biomarkers such as myoglobin, and 10 had been considered stable in healthy human urine. Of the 28 differentially expressed proteins 18 had counterparts in humans. Of these 18 proteins, 10 were members of the human core urinary proteome distributed in a variety of human tissues but concentrated in the urinary and digestive systems. Fumarylacetoacetase was verified as a potential marker of the acute hypercoagulable state by Western blot analysis. In conclusion, urine proteome analysis is a powerful approach to identify potential biomarkers of acute hypercoagulable state.