The Val34Leu Polymorphism in the A Subunit of Coagulation Factor XIII Contributes to the Large Normal Range in Activity and Demonstrates That the Activation Peptide Plays a Role in Catalytic Activity

Hemostasis components in cerebral amyloid angiopathy and Alzheimer's disease

Increased cerebrovascular amyloid-β (Aβ) deposition represents the main pathogenic mechanisms characterizing Alzheimer's disease (AD) and cerebral amyloid angiopathy (CAA). Whereas an increasing number of studies define the contribution of fibrin(ogen) to neurodegeneration, how other hemostasis factors might be pleiotropically involved in the AD and CAA remains overlooked. Although traditionally regarded as pertaining to hemostasis, these proteins are also modulators of inflammation and angiogenesis, and exert cytoprotective functions. This review discusses the contribution of hemostasis components to Aβ cerebrovascular deposition, which settle the way to endothelial and blood-brain barrier dysfunction, vessel fragility, cerebral bleeding, and the associated cognitive changes. From the primary hemostasis, the process that refers to platelet aggregation, we discuss evidence regarding the von Willebrand factor (vWF) and its regulator ADAMTS13. Then, from the secondary hemostasis, we focus on tissue factor, which triggers the extrinsic coagulation cascade, and on the main inhibitors of coagulation, i.e., tissue factor pathway inhibitor (TFPI), and the components of protein C pathway. Last, from the tertiary hemostasis, we discuss evidence on FXIII, involved in fibrin cross-linking, and on components of fibrinolysis, including tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA) and its receptor uPA(R), and plasminogen activator inhibitor-1 (PAI-1). Increased knowledge on contributors of Aβ-related disease progression may favor new therapeutic approaches for early modifiable risk factors.

Development and evaluation of a transfusion medicine genome wide genotyping array

BACKGROUND

Many aspects of transfusion medicine are affected by genetics. Current single-nucleotide polymorphism (SNP) arrays are limited in the number of targets that can be interrogated and cannot detect all variation of interest. We designed a transfusion medicine array (TM-Array) for study of both common and rare transfusion-relevant variations in genetically diverse donor and recipient populations.

STUDY DESIGN AND METHODS

The array was designed by conducting extensive bioinformatics mining and consulting experts to identify genes and genetic variation related to a wide range of transfusion medicine clinical relevant and research-related topics. Copy number polymorphisms were added in the alpha globin, beta globin, and Rh gene clusters.

RESULTS

The final array contains approximately 879,000 SNP and copy number polymorphism markers. Over 99% of SNPs were called reliably. Technical replication showed the array to be robust and reproducible, with an error rate less than 0.03%. The array also had a very low Mendelian error rate (average parent-child trio accuracy of 0.9997). Blood group results were in concordance with serology testing results, and the array accurately identifies rare variants (minor allele frequency of 0.5%). The array achieved high genome-wide imputation coverage for African-American (97.5%), Hispanic (96.1%), East Asian (94.6%), and white (96.1%) genomes at a minor allele frequency of 5%.

CONCLUSIONS

A custom array for transfusion medicine research has been designed and evaluated. It gives wide coverage and accurate identification of rare SNPs in diverse populations. The TM-Array will be useful for future genetic studies in the diverse fields of transfusion medicine research.

F13A1 Gene Variant (V34L) and Residual Circulating FXIIIA Levels Predict Short- and Long-Term Mortality in Acute Myocardial Infarction after Coronary Angioplasty

Factor XIIIA (FXIIIA) levels are independent predictors of early prognosis after acute myocardial infarction (AMI) and the Valine-to-Leucine (V34L) single nucleotide polymorphism (SNP) seems associated with lower AMI risk. Since the long-term AMI prognosis merits deeper investigation, we performed an observational study evaluating relationships between FXIIIA residual levels, cardiovascular risk-factors, and inherited genetic predispositions. FXIIIA V34L was genotyped in 333 AMI patients and a five-year follow-up was performed. FXIIIA levels assessed at day-zero (d0) and four days after AMI (d4), and conventional risk factors were analyzed, focusing on the development of major adverse cardiovascular events (MACE). FXIIIA assessed at d0 and d4 was also an independent MACE predictor in the long-term follow-up (FXIIIA_d0, Odds Ratio (OR) = 3.02, 1.79–5.1, p = 0.013; FXIIIA_d4, OR = 4.46, 2.33–8.55, p = 0.0001). FXIIIA_d4 showed the strongest MACE association, suggesting that the FXIIIA protective role is maximized when high levels are maintained for longer time. Conversely, FXIIIA levels stratified by V34L predicted MACE at a lesser extent among L34-carriers (Hazard Risk (HR)_VV34 = 3.89, 2.19–6.87, p = 0.000003; HR_L34-carriers = 2.78, 1.39–5.57, p = 0.0039), and V34L did not predict all MACE, only multiple-MACE occurrence (p = 0.0087). Finally, in survival analysis, heart failure and death differed significantly from stroke and recurrent ischemia (p = 0.0013), with FXIIIA levels appreciably lower in the former (p = 0.05). Overall, genetically-determined FXIIIA levels have a significant long-term prognostic role, suggesting that a pharmacogenetics approach might help to select those AMI patients at risk of poor prognosis in the need of dedicated treatments.

Low- versus Standard-Dose Intravenous Tissue-Type Plasminogen Activator for Acute Ischemic Stroke: An Updated Meta-Analysis

BACKGROUND

We performed a meta-analysis to compare the efficacy and safety between low- and standard-dose intravenous (IV) tissue-type plasminogen activator (tPA) for acute ischemic stroke (AIS) patients within 4.5 hours of symptom onset.

METHODS

We searched PubMed and EMBASE for relevant studies from inception to June1, 2017. Cohort or randomized controlled studies for AIS within 4.5 hours of symptom onset with comparison between low-dose and standard-dose tPA were included. The primary efficacy end point was favorable functional outcome (modified Rankin scale scores [mRS] of 0-1) at 90 days. The primary safety end point was the incidence rate of symptomatic intracerebral hemorrhage (sICH). The secondary end points were independent functional outcome (mRS scores of 0-2) and mortality.

RESULTS

A total of 11 studies were pooled in this meta-analysis. The low-dose strategy appeared to be as effective as standard-dose tPA (43.4% versus 45.4%; odds ratio [OR] = 0.93, 95% confidence interval [CI]: 0.78-1.10; P = .38) in primary efficacy outcome. The secondary efficacy outcome produced similar results (57.3% versus 57.0%; OR = 0.95, 95% CI: 0.86-1.05; P= .33). There was no evidence of statistical difference for sICH (4.2% versus 4.9%; OR = 1.02 [0.66-1.55]; P = .94) and mortality (9.0% versus 10.6%; OR = 0.99 [0.74-1.31]; P = .92) at 90 days between low- and standard-dose therapy. In a subgroup analysis by ethnicity, there was no significant difference between patients of Asian and non-Asian descent for any of the end points.

CONCLUSIONS

This study showed that AIS patients receiving low-dose IV-tPA had comparably efficacy and safety to those receiving standard-dose IV-tPA. However, the effect is especially pronounced within the Asian population, which limits the generalizability of these results.

Factor XIII Val34Leu polymorphism does not contribute to the prevention of thrombotic complications in patients with antiphospholipid syndrome

The effect of thrombophilic mutations in the development of thrombosis in patients with antiphospholipid syndrome (APS) has been extensively investigated. Factor XIII (FXIII) Val34Leu polymorphism is a newly described polymorphism which is located in the three amino acids away from the thrombin activation site of the FXIII-A subunit. It has been reported that the Leu allele decreases the risk of both arterial and venous thrombosis. In the present study, we examined the associationbetween the FXIII Val34Leu polymorphismand the developmentof thrombosisin patients with APS. Sixty APS patients with arterial and venous thrombosis, 22 antiphospholipid antibody (aPLA) positive patients with first trimester abortus and/or thrombocytopenia,126 healthy controls, and 60 healthy subjects who were age- and sex-matched with thrombotic APS group were included into the study. FXIII Leu allele frequencies in the APS patients with thrombosis, aPLA-positive patients without thrombosis, healthy controls, and matched controls were 13.3, 16, 19.5, and 18.3%, respectively. When we compared Leu allele frequencies between APS patients with thrombosis and aPLA-positive patients without thrombosis, healthy controls or matched controls, we could not find any difference (x 2, P 0.43, and P 0.09, P 0.67, respectively). Our results showed that the FXIII Leu allele has no protectiveeffect in the developmentof thrombosis in APS.

Blood coagulation factor XIII and factor XIII deficiency

Factor XIII (FXIII) is a multifunctional pro-γ-transglutaminase that, in addition to its well-known role in hemostasis, has a crucial role in angiogenesis, maintenance of pregnancy, wound healing, bone metabolism, and even cardio protection. FXIII deficiency (FXIIID) is a rare bleeding disorder (RBD) with an estimated incidence of one per two million that is accompanied by life-threatening bleeding such as umbilical cord bleeding, recurrent spontaneous miscarriage, and intracranial hemorrhage (ICH). Today, the disease is successfully managed by FXIII concentrate and recombinant FXIII for prophylaxis, management of minor and major bleeding, treatment of ICH, and successful delivery in women with recurrent pregnancy loss. Molecular analysis of patients with FXIIID revealed a wide spectrum of mutations, most frequently missense mutations in the FXIII-A subunit, with a few recurrent mutations observed worldwide. In vitro expression studies revealed that most of the missense mutations cause intracellular instability of the FXIII protein and, subsequently, FXIIID.

Prevalence of the Factor XIII Val34Leu Polymorphism in Korean Patients with Deep Vein Thrombosis

OBJECTIVE

According to recent reports, a common polymorphism resulting in Val to Leu substitution, located 3 amino acids (Val34Leu) upstream of the thrombin cleavage site of FXIII A, has been related to a lower incidence of deep vein thrombosis (DVT). And, a different expression pattern has been shown across nations and races. However, the frequency of FXIII polymorphism expression in Koreans has not been reported in normal individuals or DVT-patient groups.

DESIGN

Case-control study in Korean population.

METHODS

We investigated the distribution of factor XIII Val34Leu polymorphisms in Korean patients of DVT (50 cases) and Korean healthy controls (100 cases), using real-time polymerase chain reaction for single nucleotide polymorphism genotyping.

RESULTS

With regard to the frequency of the FXIII polymorphism in DVT patients and in the general control group, all 50 cases in the patient group and 100 cases in the control group were found to be Val34 homozygotes.

CONCLUSIONS

The Val34Leu polymorphism of FXIII was not found in Korean people, and compared with Caucasians, a noticeably low incidence of DVT was shown. Thus, the preventive effect of the Val34 allele of FXIII on the formation of thrombi was shown.

Blood coagulation factor XIII-A subunit Val34Leu polymorphisms and intracerebral hemorrhage risk: A meta-analysis of case-control studies

BACKGROUND

Previous studies investigating the association between factor XIII-A subunit (FXIII-A) Val34Leu polymorphisms and intracerebral hemorrhage (ICH) had provided inconsistent results and no large systematic review or meta-analysis had been conducted regarding this issue.

METHODS

We conducted a meta-analysis to confirm whether the FXIII-A Val34Leu polymorphisms increased the risk of ICH. Relevant studies were identified from the Pubmed, Medline, Embase, China National Knowledge Infrastructure, and Chinese Biomedicine Databases published up to September 2013. Summary odds ratios (ORs) and 95% confidence intervals (CIs) for FXIII-A Val34Leu polymorphisms and ICH were calculated in a fixed-effects model or a random-effects model when appropriate. We also carried out the stratified analyses and sensitivity analyses by region, source of control group, and sample size.

RESULTS

Eight eligible studies were reviewed. As FXIII Val34Leu was absent or had a very low prevalence among East Asians, only six studies in Caucasians were analyzed, involving 564 cases and 1276 controls. Overall, the Leu allele of FXIII gene had a trend to slightly increased odds of having ICH, but there is no statistic significance (OR1.23, 95% CI 0.94-1.61, P = 0.13). The OR of genotypes Leu+(Leu/Leu or Leu/Val) for the risk of ICH was 1.21, 95% CI 0.98-1.50, P = 0.08. And the OR of recessive model genotypes was 1.53, 95% CI 0.81-2.88, P = 0.19. There was no difference of the association between the Leu allele of FXIII gene and risk of ICH in stratified analysis.

CONCLUSIONS

Our meta-analysis suggests that there is no evidence for strong association between FXIII Val34Leu polymorphisms and ICH, but Leu allele of FXIII gene might slightly increase the risk of ICH in Caucasians. Since limited studies and subjects were included, larger scale association studies exploring the gene-gene interactions and gene-environment interactions are necessary to further validate the association.

Genetic polymorphisms and atrial fibrillation: Insights into the prothrombotic state and thromboembolic risk

The pathophysiology of thromboembolism in atrial fibrillation (AF) is a multifactorial and complex process. Abnormalities of haemostasis, fibrinolysis, endothelium, and platelets have all been described in AF. This prothrombotic state observed in AF appears to be additive to the presence of clinical and echocardiography risk factors for thromboembolism. Nonetheless, the precise mechanistic pathway(s) leading to the prothrombotic state in AF remain to be elucidated. Of note, there are limited data on the influence of genetic polymorphisms in thromboembolic risk associated with AF. On the other hand, the response to coumarin derivatives depends on several factors, such as sex, age, diet, or interacting drugs. Optimal anticoagulation control is usually hampered by significant interindividual variability in dose requirements for a given target level of anticoagulation. There is increasing evidence that interindividual sensitivity and side-effects to coumarinics may be largely determined genetically. Thus, genetic polymorphisms could explain the individual risk of developing an adverse drug reaction (bleeding) or drug inefficacy (thrombosis) with oral anticoagulation. In this article, we provide an overview of the limited data about the possible influence of genetic polymorphisms on thromboembolic risk in AF, as well as the genetic influences on anticoagulant drug responsiveness.

Coagulation factor XIII-A Val34Leu polymorphism and the risk of coronary artery disease and myocardial infarction in a Chinese Han population

There are controversial data regarding the impact of coagulation factor XIII A subunit (FXIII-A) Val34Leu polymorphism in the pathogeneric of coronary artery disease (CAD) and myocardial infarction (MI). Assuming this genetic factor is associated with the thrombotic process, we explored the role of FXIII-A Val34Leu in CAD and MI in a Chinese Han population. We recruited 195 consecutive patients with CAD confirmed by coronary angiography as well as a group of 203 controls. Factor XIII A Val34Leu polymorphism was determined through polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis. We did not find the Leu/Leu genotype in patients with CAD or controls. No significant difference in Val34Leu gene polymorphism distribution was found between patients with CAD and the controls (P = .923). Subgroup analysis according to the history of MI showed the heterozygote Val/Leu genotype was associated with a significantly decreased risk of MI (P = .005; adjusted odds ratio [OR] = 1.75; 95% confidence interval [CI] = 1.28-2.25). Furthermore, our study displayed that the frequency of the Leu34 allele in a Chinese Han population was lower than that in Caucasian populations (2.5 vs 20.4%-28.3%). Our preliminary data indicate that the FXIII-A Leu34 allele may contribute to a protective effect against the development of MI. There is a low prevalence of the Leu34 allele in Han Chinese compared to Caucasians.

The inflammatory response is influenced by FXIII VAL 34 LEU polymorphism in a human LPS model

BACKGROUND

In sepsis, activation of coagulation and inhibition of fibrinolysis lead to microvascular thrombosis. The Val34Leu polymorphism affects the function of FXIII by increasing the rate of FXIII activation by thrombin, which results in an increased and faster rate of fibrin stabilization. Sepsis and multi-organ failure cause disturbance of the normal balance of inflammation and coagulation, one of the most frequent causes of death in ICU patients. Research in polymorphism has shown the possible influence of FXIII in coagulation and inflammation.

METHODS

We analyzed the influence of the common FXIII Val34Leu polymorphism on inflammatory and coagulation parameters in human experimental endotoxinemia. Healthy volunteers (n = 62) received 2 ng endotoxin (LPS) per kg body weight as a bolus infusion over 2 min. We developed a new mutagenic separated PCR assay for determination of the FXIII promoter polymorphism.

RESULTS

FXIII levels were higher for homozygous carriers of the FXIII polymorphism in comparison with wild-type 34 Val/Val and heterozygous 34 Val/Leu. Interestingly, persons homozygous for the FXIII Val34Leu polymorphism had lower monocyte and neutrophil counts throughout the observation period, yet prothrombin fragment 1+2 and D-dimer levels did not differ after LPS challenge.

CONCLUSION

Our findings indicate that the common FXIII Val34Leu polymorphism is associated with differences in monocyte and neutrophil cell counts in response to systemic LPS infusion in humans.

Genes influencing coagulation and the risk of aneurysmal subarachnoid hemorrhage, and subsequent complications of secondary cerebral ischemia and rebleeding

Background

We investigated whether genes influencing coagulation are associated with the occurrence of aneurysmal subarachnoid hemorrhage (SAH) and with secondary cerebral ischemia and rebleeding in patients with aneurysmal SAH.

Method

Genotyping for factor V Leiden (G1691A), prothrombin G20210A, methylenetetetrahydrofolate reductase (MTHFR) C677T, factor XIII subunit A Val34Leu, Tyr204Phe and Pro564Leu, and factor XIII subunit B His95Arg was performed in 208 patients with aneurysmal SAH and in 925 controls. Secondary cerebral ischemia occurred in 49 (24%) patients and rebleeding in 28 (14%) during their clinical course of 3 months after the aneurysmal SAH. The risk of aneurysmal SAH was assessed as odds ratio (OR) with 95% confidence interval (95% CI). The risk of secondary cerebral ischemia and rebleeding was assessed as hazard ratio (HR) with 95% CI using Cox regression.

Findings

Carriers of the subunit B His95Arg factor XIII polymorphism had an increased risk of aneurysmal SAH with 23% of the patients homozygous or heterozygous for the variant allele compared to 17% of control subjects (OR 1.5, 95% CI 1.0–2.2). For the remaining genetic variants no effect on the risk of aneurysmal SAH could be demonstrated. A clear relation with the risk of secondary cerebral ischemia and of rebleeding could not be established for any of the genetic variants.

Conclusions

We found that aneurysmal SAH patients are more often carriers of the subunit B His95Arg factor XIII polymorphism compared to controls. This suggests that carriers of the subunit B His95Arg factor XIII polymorphism have an increased risk of aneurysmal SAH. Larger studies should confirm our results. As aneurysmal SAH patients who died soon after admission could not be included in the present study, our results only apply to a population of patients who survived the initial hours after the hemorrhage. For the other studied genetic factors involved in coagulation, no association with the occurrence of aneurysmal SAH or with the occurrence of secondary cerebral ischemia or rebleeding after aneurysmal SAH could be demonstrated.

Lack of association between FXIII-Val34Leu, FVII-323 del/ins, and transforming growth factor beta1 (915G/T) gene polymorphisms and bronchopulmonary dysplasia: a single-center study

Bronchopulmonary dysplasia (BPD) is a multifactorial disease of preterm infants that is characterized by airway injury, inflammation, and parenchymal remodeling. Extravascular fibrin deposits in septae and alveoli due to the altered fibrin turnover are the pathological hallmarks of BPD that strongly indicates the importance of the imbalance in the competing activities of coagulation and fibrinolysis. Activation of the coagulation cascade leads to intraalveolar fibrin deposition in many inflammatory pulmonary disorders. Increased fibrin formation or decreased fibrinolysis may cause extravascular fibrin deposition. We evaluated the association between FXIII-Val34Leu, FVII-323 del/ins, and transforming growth factor beta1 (TGF-beta(1)) (915G/T) gene polymorphisms in patients with BPD. The study group consisted of 98 preterm infants with BPD. Ninety-four of the 192 preterm neonates were without BPD and sampled for the control group. Restriction fragment size analyses were performed by examining digested PCR products for FXIII-Val34Leu, FVII-323 del/ins, and TGF-beta(1) (915G/C) genotypes. No significant associations were found between FXIII-Val34Leu, FVII-323 del/ins, TGF-beta(1) (915G/C) gene polymorphisms and BPD phenotype in our population. Further studies with other genes are required for the identification of molecular predisposing factors for BPD that may help in the development of new treatments and hence might allow for targeting of this treatment to a "high-risk" subgroup, reducing unnecessary exposure to potentially harmful therapies.

Subjects with a shortened activated partial thromboplastin time show increased in‐hospital mortality associated with elevated D‐dimer, C‐reactive protein and glucose levels

BACKGROUND

Shortened activated partial thromboplastin time (aPTT) values are associated with enhanced coagulation activation. However, the clinical relevance of shortened aPTTs is not well defined. The aim of this study was to determine the in-hospital mortality rate in subjects with shortened aPTTs and the effects of polymorphism in plasminogen activator inhibitor (PAI)-, t-PA- and factor XIII gene on the coagulation status. D-dimer, C-reactive protein (CRP) and glucose, markers that have been related with increased mortality, were tested.

RESULTS

We found that a shortened aPTT on admission was associated with an increased risk of in-hospital mortality (OR=2.6, 95% CI: 2.1-3.5). Non-survivors with short aPTTs had significantly higher plasma D-dimer, CRP and glucose levels compared with survivors. Subjects homozygous for PAI-1 5G and t-PA I alleles showed higher plasma D-dimer levels compared with 4G/4G PAI-1 (p=0.02) and D/D t-PA (p=0.001) homozygotes, respectively.

CONCLUSIONS

These results suggest that PAI-1 4G/5G and t-PA I/D polymorphisms determine plasma D-dimer levels in patients with shortened aPTT values. Preliminary results show that, among patients with short aPTTs, homozygosity for the hyperfibrinolytic PAI-1 5G or tPA I alleles are at increased risk of in-hospital mortality compared with 4G/4G PAI-1 and D/D tPA homozygotes (OR=2.6, 95% CI: 1.3-5.5 and OR=5.5, 95% CI: 1.3-24.5, respectively).

Impact of FXIII-A Val34Leu polymorphism on coronary artery disease in Croatian patients

Arterial thrombosis is the major reason for severe complications of coronary artery disease (CAD). Recently it has been suggested that the FXIII-A Val34Leu polymorphism, affecting clot stability, provides protection against thrombosis. Results published up to date implicate that there is a significant correlation between geographical area and the Leu34 allele prevalence and that its contribution to arterial thrombosis is different in different populations. The purpose of this study was to determine frequency of Leu34 allele in Croatian subjects as well as to estimate its association with a CAD. FXIII-A Val34Leu genotyping was carried out by real-time PCR method on the LightCycler using melting curve analysis with forward 5'-AACTTCCAGGACCGGCTTT-3' and reverse 5'-ACCCAGAGTGGTGGGGAA-3' primers. The Leu34 allele frequency in studied Croatian subjects was 24.3%. No significant differences were found in the prevalence of FXIII-A Val34Leu genotype or Leu34 allele distribution between studied subjects (P > 0.05). Carriage of the Leu34 allele was not significantly associated with CAD or MI risk reduction (P > 0.05). This is the first report that studies the prevalence of the Leu34 allele frequency in Croatian subjects and our results suggest that possession of the Leu 34 alele does not provide protection against MI.

Coagulation factor XIII Val34Leu gene polymorphism and Alzheimer's disease

Blood coagulation factor XIII (FXIII) plays a role in inflammatory processes and a pathogenetic role of inflammation in neurodegenerative disorders has been proposed. FXIIIa subunit was immunohistochemically detected in a subpopulation of reactive microglia in Alzheimer's disease (AD). Aim of the present study is to evaluate whether a common polymorphism of the FXIII gene is associated with sporadic AD. We examined 90 patients affected by sporadic AD and 139 age- and sex-matched controls to assess the distribution of V/L alleles and genotypes of the FXIIIa-subunit gene. The LL genotype showed a significantly higher frequency in AD patients (p<0.05) with a significantly increased risk of AD in the presence of LL genotype at the logistic regression analysis [odds ratio: 3.6 (1.36-9.44), p<0.01]. This study shows for the first time an association between FXIII Val34Leu polymorphism and AD.

FXIII gene Val34Leu polymorphism in Turkish children with cerebral infarct

A common polymorphism of the FXIIIA gene, which is characterized by a Val --> Leu exchange at amino acid position 34 (FXIII Val34Leu), was studied in this case-control study. The authors sought to determine whether there was an association between this polymorphism and pediatric stroke. The case-control study included 116 patients with cerebral infarct who were younger than 18 years. All were clinically diagnosed, and the infarction was verified with cranial imaging of the brain. The data revealed that the FXIII gene Val34Leu polymorphism was not associated independently with pediatric stroke in the population and that it does not have any effect in PT 20210A carriers. However, although the difference was not significant, the risk of thrombosis decreased 2-fold to the protective side in patients carrying FV1691A. This may be an important clue and needs further study in FV1691A carriers with and without thrombosis.

The factor XIII Val34Leu polymorphism: is it protective against idiopathic venous thromboembolism?

The substitution of leucine for valine at amino acid position 34 of the factor XIII gene is commonly referred to as FXIII Val34Leu polymorphism. The homozygous leucine/leucine genotype has been reported to confer protection against venous thromboembolism, but previous studies have not evaluated a population limited to those with idiopathic venous thromboembolism. The primary objective of the study was to determine whether the FXIII Val34Leu polymorphism is independently associated with the occurrence of idiopathic venous thromboembolism. We prospectively enrolled consecutive patients with at least one objectively confirmed idiopathic venous thromboembolism. Friends of cases were recruited as controls and matched to cases by sex, ethnicity, and age. All participants were tested for the FXIII Val34Leu polymorphism in addition to several well-known thrombophilias. Data from 309 cases and 306 controls were analyzed. The FXIII leucine/leucine genotype was present in 4.9% of cases and 6.5% of controls. An adjusted odds ratio of 0.59 (95% confidence interval, 0.25-1.38) was found for the recessive model and 0.69 (95% confidence interval, 0.46-1.02) for the dominant model. Our results do not support an independent association of the FXIII Val34Leu polymorphism with idiopathic venous thromboembolism in our Caucasian Canadian study population.

Prognostic role of factor XIII gene variants in nonhealing venous leg ulcers

OBJECTIVE

Many factors impair healing of chronic venous ulcer (CVU), and many theories have been proposed to explain their pathogenesis. Coagulation factor XIII (FXIII) influences tissue regeneration and angiogenesis with effects on wound healing. Because FXIII properties depend upon its genetic variants, we investigated whether intragene polymorphisms may have modulating effects on the CVU area.

METHODS

The study included 121 patients with nonhealing CVUs (CEAP clinical class C6) that included 67% with primary chronic venous disease (CVD), 26% with post-thrombotic ulcers, and 7% with mixed ulcer origin. Polymerase chain reaction was used to genotype them for Val34Leu, Pro564Leu, and Tyr204Phe variants in the FXIII-A subunit gene and for His95Arg variant in the FXIII-B subunit gene. The same variants were analyzed in 102 controls, healthy subjects who were case-matched by age and gender.

RESULTS

Genotype distribution for all polymorphisms investigated was not significantly different between cases and controls. Conversely, our CVU cases had a mean ulcer area inversely related with the presence of both Leu34 and Leu564 alleles (ValVal, 12.3 +/- 22.4 cm2 vs LeuLeu, 3.9 +/- 2.6 cm2, P = .002; ProPro, 10.2 +/- 21.2 cm2 vs LeuLeu, 2.9 +/- 1.4 cm2, P = .002). In combined analysis, those cases who were wild-type for both variants (ValVal34/ProPro564) had a further increase in mean ulcer size compared with cases carrying both variants (Leu34/Leu564) (13.3 +/- 27.1 cm2 vs 5.2 +/- 5.6 cm2; P = .034).

CONCLUSIONS

No correlation exists between FXIII genotypes and the prevalence of chronic venous ulcers, thus demonstrating that FXIII polymorphisms have no role in ulcer development. In contrast, FXIII-gene variants, in particular the non-wild-type alleles Leu34 and Leu564, were associated with a smaller venous ulcer surface and might have favorable effects on reparative processes.

Factor XIII Val34Leu variant is protective against venous thromboembolism: a HuGE review and meta-analysis

It has been suggested that a G-to-T transition in exon 2 of the factor XIIIA gene resulting in a substitution of leucine for valine at amino acid 34 (FXIII Val34Leu) protects against venous thromboembolism (VTE). However, the evidence to date is insufficient to incorporate testing for the FXIII Val34Leu variant into clinical practice. To determine whether genotypes with the FXIII Val34Leu variant are protective against VTE, the authors performed a meta-analysis of 12 studies with genotyping for the FXIII Val34Leu variant (3,165 objectively diagnosed VTE cases and 4,909 controls). When a random-effects model was used, the combined odds ratios for VTE were 0.63 (95% confidence interval: 0.46, 0.86) for the homozygotes of the FXIII Val34Leu variant, 0.89 (95% confidence interval: 0.80, 0.99) for the heterozygotes, and 0.85 (95% confidence interval: 0.77, 0.95) for the homozygotes and heterozygotes combined. Potential sources of heterogeneity and potential bias were explored. The meta-analysis provided evidence that the FXIII Val34Leu variant has a small, but significant protective effect against VTE. Since VTE is a complex disorder, this information, along with results of ongoing studies to identify additional genetic factors underlying VTE, will be crucial in developing accurate risk profiles to identify individuals at higher risk of VTE.

Joint linkage and association of six single-nucleotide polymorphisms in the factor XIII-A subunit gene point to V34L as the main functional locus

OBJECTIVE

Activated factor XIII (FXIII) crosslinks fibrin to enhance the mechanical strength of a blood clot and increase its resistance to fibrinolysis. The prevalence of a common variant in the FXIII-A gene (V34L) has been reported to be lower in patients with myocardial infarction and ischemic stroke than in controls, suggesting a protective role for this polymorphism in vascular diseases. The current study investigated 6 single-nucleotide polymorphisms (SNPs) within the FXIII A-subunit gene to locate functional polymorphism(s) responsible for variation in FXIII activation.

METHODS AND RESULTS

A total of 201 dizygotic twin pairs were genotyped for 1 promoter and all common nonsynonymous coding polymorphisms in the FXIII A-subunit gene: -246G>A, V34L, Y204F, P564L, V650I, and E651Q. Tests of linkage, association, and combined linkage and association were performed using QTDT software. Significant linkage to the V34L polymorphism (P=5 x 10(-12)) as well as association (P=3 x 10(-49)) was observed. Adjusting for association while performing linkage made the linkage signal disappear for the V34L polymorphism (from chi2=47.55, P=5x10(-12) to chi2=1.30, P=0.25). Only haplotypes containing the 34L allele showed association with FXIII activation.

CONCLUSIONS

Testing multiple SNPs in the FXIII A-subunit gene indicates that V34L is the main functional polymorphism influencing FXIII activation.

Factor XIII in severe sepsis and septic shock

OBJECTIVE

In sepsis, activation of coagulation and inhibition of fibrinolysis lead to microvascular thrombosis. Thus, clot stability might be a critical issue in the development of multiple organ dysfunction syndrome. Activated FXIII (FXIIIa) forms stable fibrin clots by covalently cross-linking fibrin monomers. Therefore, we investigated the impact of FXIII antigen and activity levels on disease severity and fatality in sepsis patients.

PATIENTS AND METHODS

FXIII subunit A (FXIIIA) and FXIII cross-linking activity (FXIIICA) were measured in 151 controls, in 32 patients with severe sepsis and 8 with septic shock. In addition, FXIII subunit B (FXIIIB) was measured in the sepsis patients. Moreover, clotting parameters were determined.

RESULTS

Patients suffering from sepsis (n=40) had significantly (p<0.005) lower FXIIIA levels (median [range]: 36.5% [8.8-127.4%]) and FXIIICA levels (76.5% [9.4-266%]) as compared to healthy controls (n=151, 119% [31.3-283.2] and 122.4% [40.6-485.3], respectively). No difference in FXIIIA, FXIIIB and FXIIICA levels between survivors and non-survivors, nor between patients with severe sepsis and septic shock was found. The specific activity of FXIII (FXIIICA/FXIIIA, SA(FXIII)) was significantly (p<0.001) higher in sepsis patients (2.0 [0.8-5.3]) as compared to healthy controls (1.0 [0.4-5.1]). SA(FXIII) significantly (p<0.05) increased with fatality (non-survivors [n=13] vs. survivors [n=27]: 3.3 [1.2-5.0] vs. 1.9 [0.8-5.3]) and disease severity (septic shock vs. severe sepsis: 3.4 [1.8-4.3] vs. 1.9 [0.8-5.3]).

CONCLUSION

We show decreased FXIIICA and FXIIIA levels, but higher SA(FXIII) in sepsis as compared to controls. Increased SA(FXIII) correlates with disease severity and fatality in sepsis patients.

Functional polymorphisms of FGA, encoding alpha fibrinogen, are associated with susceptibility to venous thromboembolism in a Taiwanese population

To determine the genetic risk factors for venous thromboembolism (VTE), this study examined 14 genetic variants from 10 hemostatic genes in 186 Taiwanese VTE patients and the same number of matched controls, which demonstrated FGA (encoding alpha fibrinogen) Thr312Ala polymorphism was the only variant significantly associated with VTE. Nine genetic polymorphisms on the fibrinogen cluster region of chromosome 4q28 were further studied, in which four FGA polymorphisms were found in strong linkage disequilibrium and were significantly associated with VTE by genotype and allele frequency analyses. Haplotype analysis showed significantly different FGA haplotype frequencies between VTE patients and controls with the haplotype F1, containing -1051G, -3A, 312Ala and TaqI duplication alleles, significantly associated with susceptibility to VTE (P = 0.001). Haplotype-pair analysis results also indicated a strong association of the haplotype-pair F1F1 with VTE in various VTE patient subgroups. In vitro functional analysis indicated that FGA -1051G, -3A and TaqI duplication alleles enhanced significantly the transcription level of FGA; however, control subjects with FGA genotypes containing these alleles had no elevated plasma fibrinogen levels. In conclusion, our experimental data indicated that functional genetic variants in FGA are risk factors for VTE in Taiwanese populations. Determination of FGA genotypes will likely contribute to primary prevention of this condition.

Fibrin stabilization (factor XIII), fibrin structure and thrombosis

Factor XIII (FXIII) is a zymogen that is converted into an active transglutaminase (FXIIIa) by the concerted action of thrombin and Ca2+. Its main task is to crosslink alpha-, and gamma-chains of fibrin and alpha2-plasmin inhibitor to fibrin. By this way FXIIIa strengthens fibrin and protects it from the prompt elimination by fibrinolytic system.The changes of FXIII level in thrombotic diseases are hardly explored and there are contradictory results concerning the protective effect of Val34Leu polymorphism against arterial or venous thrombosis. The results suggest that the thrombo-protective effect of Leu34 allele prevails only in certain genetic and/or environmental constellations.

Rapid detection of the factor XIII Val34Leu (163 G-->T) polymorphism by real-time PCR using fluorescence resonance energy transfer detection and melting curve analysis

The Val34Leu polymorphism in the A subunit of blood coagulation factor XIII (FXIII-A) is located in the activation peptide, just three amino acids upstream of the thrombin cleavage site. The Val-->Leu replacement accelerates the rate of the proteolytic activation of FXIII and it seems to provide protection against myocardial infarction. Methods available for the assessment of the FXIII-A Val34Leu polymorphism are rather time-consuming, laborious and not easily applicable for large-scale studies. In this study a new method based on real-time PCR with fluorescence resonance energy transfer (FRET) detection and melting curve analysis was developed. The rapid, simple method was adapted to the widely used real-time PCR instrument, LightCycler (Roche Diagnostics). The results showed 100% coincidence with those obtained by the traditional PCR-restriction fragment length polymorphism (RFLP) assay and fluorescent DNA sequencing. Using this method, an allele frequency of 24.2% was obtained (n=113), which well agrees with the allele frequency obtained by PCR-RFLP on a different group of the same ethnic Hungarian population (25.9%).

Coagulation factor XIII VaI34Leu polymorphism in patients with small vessel disease or primary intracerebral hemorrhage

BACKGROUND AND PURPOSE

Factor (F) XIII is a transglutaminase which stabilizes fibrin clots by forming cross-links between chains of fibrin. A common Val34Leu polymorphism of FXIII is correlated with the level of activated plasma FXIII. The homozygous 34Val genotype may be associated with an increased risk for thrombosis by forming fibrin fibers more resistant to fibrinolysis. The aim of the study was to investigate the association between the FXIII Val34Leu polymorphism and the risk of ischemic stroke due to small vessel disease (SVD) or the risk of primary intracerebral hemorrhage (PICH).

METHODS

66 patients with SVD stroke and 135 age- and sex-matched controls as well as 64 patients with PICH and their 127 controls were included. The FXIII Val34Leu polymorphism was genotyped using the polymerase chain reaction and restriction enzyme digestion methods.

RESULTS

The homozygous 34Val genotype was found significantly more often in patients with SVD stroke than in their controls (62 vs. 42%). On multivariate analysis, the Val/Val genotype was associated with an increased risk of SVD stroke (odds ratio: 2.1, 95% confidence interval: 1.1-3.9). The genotype distribution did not differ significantly between PICH patients and their controls (50 vs. 43%).

CONCLUSION

Our results suggest that the Val/Val genotype of FXIII could be associated with an increased risk of SVD stroke.

FXIII polymorphisms, fibrin clot structure and thrombotic risk

Fibrin clot structure is highly dependent on factor XIII activity. Activated FXIII catalyzes the formation of the peptide bonds between the gamma and alpha chains in noncovalently bound fibrin polymers and incorporates various adhesive and antifibrinolytic proteins into the final fibrin clot. In the absence of activated FXIII, clots are unstable and susceptible to fibrinolysis. Several studies have examined the effects of FXIII polymorphisms on final fibrin clot structure and clinical thrombotic risk. The Val34Leu FXIII polymorphism is associated with increased activation by thrombin. In the presence of saturating thrombin concentrations, however, FXIIIa specific enzyme activity is not affected by genetic polymorphisms. Fibrin clots formed in the presence of the FXIII 34Leu polymorphisms do tend to be thinner and less porous, however. The effects of prothrombin concentrations on clot structure have suggested that thinner clots are more resistant to fibrinolysis and associated with increased thrombotic risk. Most clinical studies of 34Leu FXIII carriers, however, have demonstrated a lower incidence of both venous and arterial thrombosis in carriers of the mutant allele compared to Val/Val carriers. One recent study has suggested that the interactions between FXIII phenotype and plasma fibrinogen concentrations significantly influence clinical thrombotic risk.

Factor XIII Val34Leu polymorphism modulates the prothrombotic and inflammatory state associated with atrial fibrillation

Atrial fibrillation (AF) has been shown to confer a prothrombotic or hypercoagulable state, which could be related to inflammation. Factor XIII (FXIII) catalyses the cross-linking of fibrin monomers, increasing clot resistance; specifically, a common polymorphism, Val34Leu, in the FXIII-A subunit gene has been associated with more rapid FXIII activation. We hypothesised a role for this polymorphism in the prothrombotic state and inflammation in AF, and tested this hypothesis by measurement of indices of coagulation (tissue factor (TF) and fibrinogen), inflammation (interleukin-6 (IL6)) and platelet activation (soluble P selectin (sPsel)).

METHODS

We studied 90 stable outpatients (73 +/- 8 years) with persistent AF. The FXIII Val34Leu polymorphism was determined by polymerase chain reaction-allelic specific restriction assay (PCR-ASRA). Prevalence of Val34Leu polymorphism of patients was compared to 585 unrelated subjects from the same geographical area. Plasma fibrinogen (Clauss), TF, IL6 and sPsel (all ELISA) were quantified in patient group. Research indices were compared to 74 controls in sinus rhythm with similar clinical characteristics.

RESULTS

There were no statistical differences in FXIII polymorphism prevalence between AF patients and controls. Patients carrying the Leu34 allele had higher plasma levels of TF, IL6 and sPsel (all P < 0.05) compared to controls. Plasma IL6 and TF levels were significantly correlated (Spearman coefficient, r = 0.33, P < 0.01). On multivariate analysis, the Leu34 allele was independently associated with IL6 levels (P < 0.01), whereas TF levels were only associated with IL6 concentrations. However, sPsel and fibrinogen levels were not related to Leu34 allele.

CONCLUSION

FXIII Val34Leu polymorphism was independently associated with IL6 levels in AF. The Leu34 allele may potentially influence the prothrombotic state in these patients by modulating the inflammatory state.

Selective pressure has not acted against hypercoagulability alleles in high-altitude Amerindians

Elevated hematocrit increases blood oxygen carrying capacity in high-altitude populations, but blood viscosity and coaguability may increase concomitantly. Alleles of the beta-fibrinogen gene (FGB) associated with lower fibrinogen levels are more common in highland Amerindians (Quechua) than lowland Amerindians (Na-Dene). Although genetic drift could account for this, selection may have acted against transmission of hypercoagulability alleles at high altitude. To test this hypothesis, we compared allele frequencies between Quechua and more closely related lowlanders (Maya) at loci in the genes encoding beta-fibrinogen (FGB), factors V (F5), VII (F7) and XIII (F13), alpha2-integrin (ITGA2) and plasminogen activator inhibitor type 1 (PAI-1; SERPINE1). No significant differences in allele frequencies were found except 485arg in the gene encoding factor V, which was more common in the Quechua. These data do not support the hypothesis that selection has acted to eliminate alleles associated with hypercoagulability in Andean highlanders.

Combined carrier status of prothrombin 20210A and factor XIII-A Leu34 alleles as a strong risk factor for myocardial infarction: evidence of a gene-gene interaction

Studies associating the prothrombin 20210G>A (FII 20210A), factor V Leiden (FVL), and factor XIII Leu34 (FXIII-A Leu34) alleles with myocardial infarction (MI) have yielded conflicting results. Complicated gene-gene interactions, small sample sizes, and heterogeneous genetic and environmental backgrounds may contribute to opposing findings. Simultaneous analysis of multiple gene variants in a large sample size from a genetically isolated population may overcome these weaknesses. Genotyping was performed in 500 MI patients and 500 control subjects from the genetically isolated Newfoundland population to determine the prevalence of the FII 20210A, FVL, and FXIII-A Leu34 variants and their association with MI. Gene-gene interactions were also analyzed. The prevalence of the FII 20210A allele was higher in MI patients (3.2%) than in control subjects (1.0%; P =.015). The FII 20210A allele was also 5.6-fold higher in MI patients younger than 51 years than in age-matched control subjects (P =.04). FVL showed 3.9-fold higher prevalence in young patients than in patients older than 50 years (P =.004) and 2.7-fold higher than in age-matched control subjects (P =.007). Furthermore, the prevalence of combined carriers of the FXIII-A L34 and FII 20210A alleles was 12-fold higher in MI patients than in control subjects (P =.002) and with 92% penetrance. There was disequilibrium of the FXIII-A Leu34 allele to MI patients carrying the FII 20210A allele as a genetic background. Based on our data, we determined that (1) the FII 20210A allele is a risk factor for MI, possibly important for early onset; (2) FVL may predispose for early-onset MI; (3) the FXIII-A Leu34 allele predisposes for MI in males only; however, (4) interaction between the FII 20210A and FXIII-A Leu34 alleles forms a synergistic coeffect that strongly predisposes for MI, placing combined carriers at high risk for MI.

Factor XIII polymorphisms and venous thromboembolism

OBJECTIVE

To review the relationship between factor XIII polymorphisms and venous thromboembolism.

METHODS

Review of the medical literature using computerized databases and secondary sources identified through reviews of bibliographies.

DATA SYNTHESIS

Plasma factor XIII is the precursor of a transglutaminase that cross-links fibrin, thereby altering its properties, including resistance to fibrinolysis. It is, therefore, biologically plausible that alterations in factor XIII activity could affect thrombosis risk. There are 4 common polymorphic forms of factor XIII that differ among ethnic groups. The Val34Leu polymorphism results in an amino acid change near the thrombin cleavage site that may alter the rate of activation. Several case-control studies have investigated the relation of the Val34Leu polymorphism to venous thromboembolism. Some have shown a potentially protective effect of this polymorphism, but the association is not consistent.

CONCLUSION

Evidence is conflicting regarding the association of the factor XIII Val34Leu polymorphism with risk of venous thromboembolism, and further studies are needed before screening for this polymorphism can be recommended for evaluation of thrombophilia.

Factor XIII Val34Leu polymorphism, factor XIII antigen levels and activity and the risk of deep venous thrombosis

Varying results on the effect of factor XIII (FXIII) Val34Leu on venous thrombotic risk have been reported. The probability of a true association between this polymorphism and venous thrombotic risk would be enhanced by a laboratory phenotype associated with this polymorphism and with the thrombotic risk. The aim of this study was to assess the effect of FXIII Val34Leu, FXIII activity and subunit levels on venous thrombotic risk in a large case-control study, The Leiden Thrombophilia study (LETS). We found higher FXIII activity for 34Leu carriers (Leu/Leu: 158.0, Val/Val: 95.0). FXIII subunit levels were not associated with genotype. Higher FXIII activity was associated with a slightly decreased thrombotic risk [Odds ratio (OR): 0.8, 95% confidence intervals (CI): 0.5-1.3]. This effect was not present for elevated FXIII subunit levels. Higher FXIII activity was also associated with a higher dissociation index (percentage A2B2 complex dissociated after activation by thrombin for a fixed time interval). This index was higher for FXIII 34Leu carriers. The risk of deep venous thrombosis was slightly decreased for carriers of the 34Leu allele [OR: 0.9 (95%CI: 0.7-1.1)]. For homozygous 34Leu carriers the OR was 0.7 (95%CI: 0.4-1.3). This finding, suggesting a weak protective effect, was completely restricted to men. An overall estimate of thrombotic risk was calculated by using earlier reports on the risk of FXIII Val34Leu. The overall risk estimate for homozygous 34Leu carriers was 0.8 (95%CI: 0.6-1.0). In this study, a weak protective effect against venous thrombosis was found, of FXIII 34Leu as well as of increased FXIII activity.

Genetics of primary intracerebral hemorrhage

Genetic studies of primary intracerebral hemorrhage (PICH) have begun to yield important biologic insights into the pathogenesis of this disorder. This review of candidate genes for PICH emphasizes the value of focusing on individual pathogenic phenotypes. One type of PICH in particular, cerebral amyloid angiopathy, is known to have specific genetic factors regulating both its familial and sporadic forms. Another promising research method is to focus on pathways involved in hemostasis that may be etiologically relevant to all types of PICH. Genetic studies will improve our understanding of the biology of PICH, and may eventually be incorporated into clinical decision making regarding anticoagulation.

The effect of the Val34Leu polymorphism in the factor XIII gene in infants with a birth weight below 1500 g

OBJECTIVES

The 34Leu polymorphism of the factor XIII gene is associated with a low rate of brain infarction and a higher incidence of primary intracerebral hemorrhage in adults. We evaluated the effect of the polymorphism on the subsequent development of isolated intracranial hemorrhage and white matter disease in preterm infants with a birth weight <1500 g (very low birth weight [VLBW] infants).

STUDY DESIGN

We studied 531 VLBW infants and 301 control infants born at term. The factor XIII 34Leu polymorphism was detected by polymerase chain reaction and restriction enzyme digestion.

RESULTS

Allele frequencies were not different from term and VLBW infants (Val/Val, 53.1% and 57.8%; Val/Leu, 38.8% and 37.6%; Leu/Leu, 8.0% and 4.5%, respectively). VLBW infants carrying the Leu/Val or Leu/Leu allele had a significant reduced risk of the development of white matter disease (3.6% vs 10.4% in infants without the polymorphism, P =.003). In a multivariate logistic regression analysis, only gestational age <28 weeks (odds ratio, 3.8; 95% confidence interval, 1.9-7.5; P <.001), and the factor XIII 34Leu allele (odds ratio, 0.3; 95% confidence interval, 0.1-0.7; P =.005) had significant prognostic value in predicting subsequent white matter disease. However, VLBW infants who carried the factor XIII 34Leu allele also had a moderately increased risk of the subsequent development of isolated intraventricular hemorrhage (14.3% vs 10.1% in infants without the mutation, P =.17).

CONCLUSIONS

VLBW infants carrying the factor XIII 34Leu polymorphism had a decreased risk for white matter disorders.

Genetic variants of the hemostatic system and development of transplant coronary artery disease

BACKGROUND

The occurrence of coronary artery disease (CAD) after heart transplantation may represent an accelerated inflammatory and thrombotic response to coronary vascular endothelial cell injury. Several common mutations involving hemostasis and cellular adhesion proteins have been associated with genetic susceptibility to native coronary heart disease. The clinical setting of heart transplantation provides a unique opportunity to examine the relative contribution of circulating (i.e., recipient) vs local vascular (i.e., donor) hemostatic components to the occurrence of CAD.

METHODS

We performed genotyping for several common hemostatic polymorphisms among 53 cardiac transplant patients and their heart donors. Patients were observed for an average of 43 months, and the presence of transplant CAD was determined by coronary angiography.

RESULTS

The development of transplant CAD did not relate to recipient hemostatic genotype, but 2 donor polymorphisms (PAI-1 4G/5G and alpha(2) integrin C807T) were important predictors of transplant CAD. The risk ratio (RR) of transplant CAD associated with donor PAI-1 4G/4G genotype was 2.6 (95% confidence interval [CI] 1.1-6.2) and was modified by recipient cytomegalovirus status, hyperlipidemia, diabetes, and recipient factor XIII Val34Leu genotype. The RR of transplant CAD associated with donor alpha(2) integrin 807 T/T genotype was 7.4 (95% CI, 2.5-22.0).

CONCLUSIONS

Genetic and metabolic factors contributed by both donor and recipient may interact at the level of the coronary vessel wall in the development of transplant-associated CAD, and this finding may provide additional support for the importance of local thrombotic response to endothelial injury in the pathogenesis of this disorder.

Coagulation factor XIII and markers of thrombin generation and fibrinolysis in patients with inflammatory bowel disease

OBJECTIVE

To relate factor XIII levels and other prothrombotic markers to inflammatory bowel disease and investigate the frequency of valine34leucine and its effect on factor XIII cross-linking activity in patients with inflammatory bowel disease.

DESIGN

Fifty patients with active inflammatory bowel disease but no venous thromboembolism (32 with ulcerative colitis, 18 with Crohn's disease), 50 patients with inactive inflammatory bowel disease but no venous thromboembolism (32 with ulcerative colitis, 18 with Crohn's disease), two age- and gender-matched healthy control groups of 100 subjects each were recruited. To further explore the relationship between valine34leucine and inflammatory bowel disease, 21 patients with the disease (13 with ulcerative colitis and eight with Crohn's disease) and venous thromoembolism (male to female ratio = 7 : 14, median age 59.5 years (range, 19-80 years)) were recruited. Two hundred and fifteen control subjects (M : F = 121 : 94, median age 62 years (28-74 years)), with venous thromboembolism (119 with deep venous thrombosis, and 96 with pulmonary embolism) were drawn from the same geographical area as the patients.

METHODS

Factor XIII A, B-subunit antigen and A2B2 tetramer levels were measured using an in-house sandwich enzyme-linked immunoassay method.

RESULTS

Factor XIII A2B2 tetramer and the A-subunit were significantly decreased in patients with active inflammatory bowel disease compared with controls (59% vs 95%, P < 0.0001 and 75% vs 102%, P < 0.0001, respectively), but not between the inactive inflammatory bowel disease group and controls. The D-dimer and prothrombin 1+2 fragment levels in patients with active inflammatory bowel disease were raised compared with controls (178 (152) vs 109 (84), P = 0.0007 and 82 (43) vs 55 (28), P = 0.0001, respectively). The factor XIII B-subunit and factor XIII cross-linking activity were not significantly different between patients with active or inactive inflammatory bowel disease and controls. There was no significant difference in genotype distribution in inflammatory bowel disease patients with or without venous thromboembolism and respective control subjects. Levels of tissue plasminogen activator antigen were significantly increased in patients with active inflammatory bowel disease when compared to inactive inflammatory bowel disease and controls (8.9 (3.7) vs 6.7 (3.4) vs 6.9 (3.4), P < 0.001).

CONCLUSIONS

Active inflammatory bowel disease is associated with activation of coagulation. Factor XIII A and A2B2 tetramer levels were markedly decreased in active inflammatory bowel disease. Variations in the level of factor XIII in patients with inflammatory bowel disease could be multifactorial and in part may result from the increased formation of microthrombi and accelerated turnover of the factor XIII. We found no evidence of association of factor XIII valine34leucine polymorphism and inflammatory bowel disease.

Factor XIIIA Val34Leu polymorphism does not predict risk of coronary heart disease: The Atherosclerosis Risk in Communities (ARIC) Study

Factor XIII catalyzes the cross-linking of fibrin. Cross-sectional studies have suggested that a common polymorphism site at residue 34 of the A subunit of factor XIII (FXIIIA) with a substitution of Leu for Val (FXIIIA Val34Leu) was associated with reduced coronary heart disease (CHD). This association has not been examined in prospective studies. Healthy subjects (n=15 792) were recruited from 4 US communities into the Atherosclerosis Risk in Communities (ARIC) study from 1987 to 1989. They were followed, and incident CHD events were identified and verified. For the present study, we included 423 patients with CHD as cases and 479 noncases. FXIIIA Val34Leu polymorphism was determined by the single-strand conformational polymorphism method. There were no significant differences in the genotype frequencies between cases and noncases. The genotypes showed little association with known CHD risk factors. A weighted proportional hazards regression analysis adjusting for other risk factors confirmed no association of the genotypes with risk of CHD. This prospective study did not provide evidence of a reduced CHD risk for the FXIIIA 34Leu allele.

Influence of blood coagulation factor XIII and FXIII Val34Leu on plasma clot formation measured by thrombelastography

Blood coagulation factor XIII (FXIII) plays an important role in the final stage of the blood coagulation process. Thrombelastography (TEG) enables global assessment of the hemostatic function. The present study tested for the first time the specificity and sensitivity of the rotation thrombelastography (ROTEG: rotation thrombelastography) method for the influence of FXIII and the FXIIIVal34Leu polymorphism on thrombelastograms measured in citrated plasma. Three thrombelastographic parameters were determined in (a) citrated pool plasma, (b) FXIII-deficient plasma, (c) different mixtures of both, and (d) in 60 plasma samples genotyped for FXIIIVal34Leu. Thrombelastograms from FXIII-deficient plasma were significantly smaller than those from pool plasma (8 mm vs. 20.9 mm). Increasing amounts of pool plasma added to FXIII-deficient plasma led to an increase in maximum clot firmness (MCF). FXIIIVal34Leu showed an influence on clot formation time (CFT) values, which decreased with increasing number of Leu alleles. The difference between the wild type and the homozygote mutant genotype was statistically significant (median 185.3 vs. 86.0 s, P=.031). ROTEG is a simple but effective method for the investigation of FXIII function in plasma. The ROTEG method has shown to be not only specific for the FXIII influence, as effects exclusively dependent on FXIII could be observed, but also sensitive, as already smallest amounts of FXIII could be detected. Additionally, the impact of a common genetic polymorphism on ROTEG could be shown for the first time.

Role of factor XIII Val34Leu polymorphism in retinal artery occlusion

BACKGROUND AND PURPOSE

Factor XIII (FXIII) Val34Leu, a common polymorphism in the gene for factor XIII, has been associated with a lower risk of stroke, myocardial infarction, and deep vein thrombosis. Ineffective fibrin cross-linking has been suggested to be causative. The aim of the present case-control study was to investigate the role of FXIII Val34Leu polymorphism in patients with retinal artery occlusion.

METHODS

A total of 108 patients with retinal artery occlusion and 313 age- and sex-matched controls were genotyped for the FXIII Val34Leu polymorphism. Factor XIII Val34Leu genotypes were determined by use of allele-specific polymerase chain reaction.

RESULTS

Homozygous Leu genotype was found significantly more often in control subjects than in patients with retinal artery occlusion (P=0.018), with an odds ratio of 0.22 (95% confidence interval 0.07 to 0.74). Distribution of the Val/Val and Val/Leu genotypes did not differ significantly between groups.

CONCLUSIONS

Because prevalence of homozygous Leu genotype was significantly higher in controls, we conclude that the Leu/Leu genotype is associated with a protective effect against retinal artery occlusion.