Genotype/Phenotype Correlations for Coagulation Factor XIII: Specific Normal Polymorphisms Are Associated With High or Low Factor XIII Specific Activity

Thrombophilic gene polymorphisms and recurrent pregnancy loss: a systematic review and meta-analysis

PURPOSE

Recurrent pregnancy loss (RPL) is affecting 1-4% of women who conceive approximately, and no cause could be found in more than 50% of women suffering from RPL. Inherited thrombophilias have got increasing attention in women with unexplained RPL, so we aim to explore the relationship among these most common thrombophilic polymorphisms and RPL through a literature review and meta-analysis.

METHODS

Observational studies from PubMed, Embase, Cochrane, and Web of Science from 1997 to 7 April 2022 were searched. For each genetic variant, a fixed or random-effect model was used according to the heterogeneity test to calculate pooled ORs and 95% CIs for both dominant and recessive genetic models. Egger's line regression test was used to assess publication bias. The quality of the included articles was assessed by the Newcastle Ottawa scale.

RESULTS

A total of 124 articles comprising 17,278 RPL patients and 16,021 controls were included. Results showed that hyperhomocysteinemia (MTHFR) C677T (dominant model: OR, 1.43; 95% CI, 1.25-1.64; recessive model: OR, 1.60; 95% CI, 1.36-1.87), MTHFR A1298C (dominant model: OR, 1.66; 95% CI, 1.26-2.18; recessive model: OR, 1.79; 95% CI, 1.42-2.26), PAI-1 4G/5G (dominant model: OR, 1.67; 95% CI, 1.36-2.06; recessive model: OR, 1.80; 95% CI, 1.39-2.32), angiotensin-converting enzyme I/D (OR, 1.23; 95% CI, 1.00-1.53), Factor XIII V34L (OR, 1.38; 95% CI, 1.02-1.87), and β-fibrinogen-455G/A (OR, 1.60; 95% CI, 1.02-2.51) were significantly associated with RPL.

CONCLUSION

This study provides potentially useful clinical markers to evaluate the risk of RPL or to help unexplained RPL patients identify possible causes, which may allow for targeted treatment.

Genetic landscape in coagulation factor XIII associated defects – Advances in coagulation and beyond

Coagulation factor XIII (FXIII) acts as a fine fulcrum in blood plasma that maintains the balance between bleeding and thrombosis by covalently crosslinking the pre-formed fibrin clot into an insoluble one that is resistant to premature fibrinolysis. In plasma, FXIII circulates as a pro-transglutaminase complex composed of the dimeric catalytic FXIII-A encoded by the F13A1 gene and dimeric carrier/regulatory FXIII-B subunits encoded by the F13B gene. Growing evidence accumulated over decades of exhaustive research shows that not only does FXIII play major roles in both pathological extremes of hemostasis i.e. bleeding and thrombosis, but that it is, in fact, a pleiotropic protein with physiological roles beyond coagulation. However, the current FXIII genetic-epidemiological literature is overwhelmingly derived from the bleeding pathology associated with its deficiency. In this article we review the current clinical, functional, and molecular understanding of this fascinating multifaceted protein, especially putting into the same perspective its genetic landscape.

Factor XIII-A Val34Leu and Tyr204Phe variants influence clot kinetics in a cohort of South African type 2 diabetes mellitus patients

Factor XIII, a transglutaminase that plays a crucial role in clot formation, consists of subunits A and B. Single nucleotide polymorphisms in Factor XIII-A have been linked to thrombotic risk. In Type 2 Diabetes mellitus (T2DM), a hypercoagulable state is thought to contribute to the high mortality rate associated with thrombotic diseases. Due to the lack of prevalence data of FXIII-A single nucleotide polymorphisms (SNPs) in T2DM in a South African cohort, this study assessed the prevalence FXIII-A Val34Leu (rs5985) and Tyr204Phe (rs3024477) SNP's and the effect on clot kinetics in T2DM.

MATERIALS AND METHODS

A cohort of T2DM patients (n = 100) and race, age and gender matched healthy controls (n = 101) were recruited following ethical approval. Thromboelastography® (TEG®) was used to assess the viscoelastic properties in platelet poor plasma (PPP) in controls (n = 91) and T2DM patients (n = 91) younger than 50 years old. Genomic DNA was isolated from whole blood using the Quick-DNA™ Miniprep Plus Kit and PCR-RFLP was used to genotype each sample for FXIII-A rs5985 and rs3024477 SNPs.

RESULTS

TEG® analyses indicated a longer R-time (p < 0.0001) and higher TMRTG (p < 0.0001) in PPP of T2DM patients. Control and T2DM genotype distribution conformed to Hardy-Weinberg equilibrium (p > 0.05). There was a higher prevalence of the wildtype genotype of FXIII-A Tyr204Phe (rs3024477) SNP in T2DM (OR = 0.23, 95% CI = 0.12-0.42, p < 0.0001). The 204Phe variant was more frequent in the Caucasians (OR = 0.39, 95% CI = 0.05-0.33, p < 0.0001). The presence of the 204Phe variant in T2DM affected TMRTG (p = 0.0207). The variant affected R time (p = 0.0432) and TMRTG (p = 0.0209 and p = 0.0207) in controls and T2DM, respectively.

CONCLUSION

An inverse association with T2DM and FXIII-A Tyr204Phe was found. A hypo coagulable PPP clot profile was observed in T2DM. A shorter reaction time was observed and but faster rate at which the clot reached maximum strength in both controls and T2DM in the presence of the 204Phe variant.

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.

Mild Acquired Factor XIII Deficiency and Clinical Relevance at the ICU-A Retrospective Analysis

Acquired FXIII deficiency is a relevant complication in the perioperative setting; however, we still have little evidence about the incidence and management of this rarely isolated coagulopathy. This study aims to help find the right value for the substitution of patients with an acquired mild FXIII deficiency. In this retrospective single-center cohort study, we enrolled critically ill patients with mild acquired FXIII deficiency (>5% and ≤70%) and compared clinical and laboratory parameters, as well as pro-coagulatory treatments. The results of the present analysis of 104 patients support the clinical relevance of FXIII activity out of the normal range. Patients with lower FXIII levels, beginning at <60%, had lower minimum and maximum hemoglobin values, corresponding to the finding that patients with a minimum FXIII activity of <50% needed significantly more packed red blood cells. FXIII activity correlated significantly with general coagulation markers such as prothrombin time, activated partial thromboplastin time, and fibrinogen. Nevertheless, comparing the groups with a cut-off of 50%, the amount of fresh frozen plasma, thrombocytes, PPSB, AT-III, and fibrinogen given did not differ. These results indicate that a mild FXIII deficiency occurring at any point of intensive care unit stay is also probably relevant for the total need of packed red blood cells, independent of pro-coagulatory management. In alignment with the ESAIC guidelines, the measurement of FXIII in critically ill patients with the risk of bleeding and early management, with the substitution of FXIII at levels <50%-60%, could be suggested.

Refractory Duodenal Bleeding Ulcers Successfully Treated with Factor XIII Transfusion

A 67-year-old woman with a history of autoimmune hepatitis was admitted for fever, acute hepatic dysfunction, and acute kidney injury. She was diagnosed with multiple duodenal ulcers. Despite the administration of proton pump inhibitor and red blood cells, her black stool and anemia progressed, and she was therefore transferred to our hospital. Despite hemostatic treatments, she continued to bleed. On the 21st day of admission, an endoscopic examination showed the oozing of blood from the duodenal mucosa. A low factor XIII (FXIII) activity level was detected, and she was administered FXIII concentrate. The bleeding stopped and she was thereafter discharged.

Combinations of fibrinolytic gene polymorphisms (plasminogen activator inhibitor type 1 4G/5G, factor XIII Val34Leu and angiotensin-converting enzyme I/D) in women with idiopathic infertility

During normal pregnancy depressed fibrinolytic system is caused by changes in many factors, which could be influenced by different gene polymorphisms. The aim of this study was to investigate the combination of fibrinolysis-related gene polymorphisms in women with idiopathic infertility. We genotype polymorphisms 4G/5G in plasminogen activator inhibitor type 1 (PAI-1), Val34Leu in factor XIII (FXIII) and I/D in angiotensin-converting enzyme (ACE) gene. The patients group consisted of 83 females with idiopathic infertility, while the control group included 121 females with at least one born child. The alleles and genotypes distributions showed no significant differences between analyzed groups. Although higher frequency of PAI-1 5G5G genotype in patients did not reach statistical significance, 5G5G genotype of PAI-1 in combination with ValVal genotype of FXIII leads to higher risk for infertility (P < 0.05). In addition, when we added ACE I/D polymorphism in analysis, the 4G in PAI-1 and D allele in ACE, showed protective effect in combination with FXIII polymorphism (P < 0.05). The finding that combined homozygosity of 5G of PAI-1, commonly associated with greater fibrinolytic activity and bleeding tendency, in combination with Val genotype of FXIII impose a risk for female idiopathic infertility. The protective effect of alleles 4G (PAI-1) and D (ACE) suggest that different combinations of polymorphisms influencing fibrinolysis could lead to better established hemostatic balance and reproductive success. Further analyses, with larger number of samples, as well as assessment of additional biochemical parameters of fibrinolysis, should be performed to clarify the role of gene polymorphisms on fibrinolysis and consequently their influence on reproductive success.

Circulating microparticle proteins obtained in the late first trimester predict spontaneous preterm birth at less than 35 weeks' gestation: a panel validation with specific characterization by parity

BACKGROUND

We have previously shown that protein biomarkers associated with circulating microparticles proteins (CMPs) obtained at the end of the first trimester may detect physiologic changes in maternal-fetal interaction such that the risk of spontaneous preterm delivery ≤35 weeks can be stratified.

OBJECTIVES

We present here a study extension and validation of the CMP protein multiplex concept using a larger sample set from a multicenter population that allows for model derivation in a training set and characterization in a separate testing set.

MATERIALS AND METHODS

Ethylenediaminetetraacetic acid (EDTA) plasma was obtained from 3 established biobanks (Seattle, Boston, and Pittsburgh). Samples were from patients at a median of 10-12 weeks' gestation, and the CMPs were isolated via size-exclusion chromatography followed by protein identification via targeted protein analysis using liquid chromatography-multiple reaction monitoring-mass (LC-MRM) spectrometry. A total of 87 women delivered at ≤35 weeks, and 174 women who delivered at term were matched by maternal age (±2 years) and gestational age at sample draw (±2 weeks). From our prior work, the CMP protein multiplex comprising F13A, FBLN1, IC1, ITIH2, and LCAT was selected for validation.

RESULTS

For delivery at ≤35 weeks, the receiver operating characteristic (ROC) curve for a panel of CMP proteins (F13A, FBLN1, IC1, ITIH2, and LCAT) revealed an associated area under the ROC curve (AUC) of 0.74 (95% CI, 0.63-0.81). A separate panel of markers (IC1, LCAT, TRFE, and ITIH4), which stratified risk among mothers with a parity of 0, showed an AUC of 0.77 (95% CI, 0.61-0.90).

CONCLUSION

We have identified a set of CMP proteins that provide, at 10-12 weeks gestation, a clinically useful AUC in an independent test population. Furthermore, we determined that parity is pertinent to the diagnostic testing performance of the biomarkers for risk stratification.

Coagulopathy in Type 2 Diabetes Mellitus: Pathological Mechanisms and the Role of Factor XIII-A Single Nucleotide Polymorphisms

The prevalence of type 2 diabetes mellitus (T2DM) has quadrupled within three decades since 1980, affecting 422 million adults in 2016. It remains one of the most common noncommunicable chronic diseases and the underlying risk factor for cardiovascular diseases worldwide. There are different underlying mechanisms that play a role in the development of pathologies associated with the disease such as hyperglycaemia, oxidative stress, obesity, inflammation and hypercoagulation; each of which are interlinked. Hyperglycaemia, oxidative stress and obesity play a huge role in the activation of inflammation and coagulation. Activation of inflammatory pathways increases the production of thrombin which predisposes the development of thrombotic related diseases. One of the factors that contribute to the increase of thrombin is the impairment of the fibrinolysis process due to decreased expression of tissue-plasminogen activator (tPA) by increased levels of plasminogen activator inhibitor-1 (PAI-1). Coagulation factor XIII (FXIII), a transglutaminase that is composed of subunits A and B (FXIII-A2B2), is essential for the last step of fibrin clot formation in the coagulation pathway. Genetic variation of FXIII-A in the form of single nucleotide polymorphisms (SNPs) alters the activity of FXIII, altering clot properties which influence disease outcomes. This review discusses the link between underlying mechanisms of T2DM, well known FXIII-A variants and coagulation.

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.

Factor XIII polymorphism and risk of aneurysmal subarachnoid haemorrhage in a south Indian population

BACKGROUND

The rupture of a brain aneurysm causes bleeding in the subarachnoid space and is known as aneurysmal subarachnoid haemorrhage (aSAH). In our study, we evaluated the association of factor XIII polymorphism and the risk of Aneurysmal subarachnoid haemorrhage (aSAH) in South Indian population.

METHODS

The study was performed in 200 subjects with aSAH and 205 healthy control subjects. Genotyping of rs5985(c.103G > T (p.Val35Leu)) and rs5982(c.1694C > T (p.Pro564Leu)) polymorphism was performed by Taqman® allelic discrimination assay.

RESULTS

In our study, Val/Leu genotype frequency was higher in control subjects (18%) compared to aSAH patients (9%).The Val/Leu genotype was associated with lower risk of aSAH (OR = 0.48, 95%CI = 0.26-0.88, p = 0.02). When compared with Val allele, Leu allele was significantly associated with lower risk of aSAH (OR = 0.55, 95%CI = 0.32-0.95, p = 0.03). In subtyping, we found a significant association of Leu/Leu genotype with the Basilar top aneurysm (OR = 3.59, 95%CI = 1.11-11.64, p = 0.03). In c.1694C > T (p.Pro565Leu) variant, Pro/Pro Vs Pro/Leu genotype (OR = 2.06, 95%CI = 1.10-3.85, p = 0.02) was significantly associated with higher risk of aSAH. The 564Leu allelic frequency in aSAH patients (36%) was higher when compared with that in healthy controls (30%) in our study. When allele frequency (Pro Vs Leu) was compared, 564Leu allele was found to be significantly associated with higher aSAH risk (OR = 1.36, 95%CI = 1.01-1.83, p = 0.04). (OR = 1.36, 95%CI = 1.01-1.83, p = 0.04). Regarding rs5985 and rs5982, significant association was found in the log-additive model (OR = 0.57, 95%CI = 0.33-0.97, p = 0.034; OR = 1.32, 95%CI = 1.00-1.72, p = 0.043).

CONCLUSION

These results suggest that 34Leu allele was a protective factor for lower risk of aSAH whereas 564Leu allele was associated with higher risk of aSAH in South Indian population.

A large case series on surgical outcomes in congenital factor XIII deficiency patients in Iran

Essentials Data on surgery in factor XIII (FXIII) deficiency patients are scarce and lack standardized guidelines. Variable dosage of 10-50 U kg-1 was given to FXIII deficiency patients undergoing surgery. Surgical outcomes showed excellent hemostasis with a minimal risk of post-operative complications. Surgery can be performed safely in FXIII deficiency patients following FXIII administration.

SUMMARY

Background The lack of accepted standardized surgical guidelines leads to dependence on the treating physicians' and centers' experiences. Aim Our aim is to evaluate the surgical outcomes of a large group of congenital factor XIII deficiency (FXIIID) patients. Methods A case series study was conducted prior to surgery on congenital FXIIID patients in two major referral centers located in Iran from 2010 to 2016. All patients were on prophylaxis using plasma factor XIII concentrate (10 U kg-1 , every 28 days) except for three patients. Single doses of 10 U kg-1 or 30 U kg-1 plasma factor XIII concentrate were given before a minor procedure and circumcision, respectively. Two doses of plasma factor XIII concentrate, one 30 U kg-1 prior to the procedure and the second dose of 30 U kg-1 on postoperative day 3, were given for major surgery. The dose was 50 U kg-1 both before and after neurosurgical procedures. Results One hundred and sixty-two FXIIID patients underwent minor, major and obstetrical/gynecological surgeries. Median age of the patients was 14 years (ages ranged 15 days to 47 years). The male-to-female ratio was 89/73. Five postoperative complications, two bleeding and three thrombosis, were recorded. Conclusion Our study showed excellent hemostasis in FXIIID patients undergoing surgeries. During the period of these surgeries, we observed only 1.8% postoperative complications. Surgery can be performed safely in FXIIID patients, and our proposed treatment regimens lead to adequate hemostatic coverage with minimal risk, for both minor and major surgeries.

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.

Factor XIII A-Subunit V34L Variant Affects Thrombus Cross-Linking in a Murine Model of Thrombosis

OBJECTIVE

Factor XIII (FXIII) cross-links fibrin upon activation by thrombin. Activation involves cleavage at residue 37 by thrombin, releasing an activation peptide. A common polymorphism (valine to leucine variant at residue 34, V34L), located in the activation peptide, has been associated with increased activation rates and paradoxically a protective effect in cardiovascular disease. There is, currently, no data available on the effects of V34L from in vivo models of thrombosis. We examined the effect of FXIII V34L on clot formation and cross-linking in vivo.

APPROACH AND RESULTS

We generated a panel of full-length recombinant human FXIII-A2 variants with amino acid substitutions in the activation peptide to investigate the effect of these variants on activation rate, and we used wild-type, V34L, and alanine to glycine variant at residue 33 variants to study the effects of varying FXIII activation rate on thrombus formation in a murine model of FeCl3 injury. FXIII activation assay showed that residues 29, 30, 33, and 34 play a critical role in thrombin interaction. Full-length recombinant human FXIII-A2 V34L has significant effects on clot formation, structure, and lysis in vitro, using turbidity assay. This variant influenced fibrin cross-linking but not size of the thrombus in vivo.

CONCLUSIONS

Mutations in the activation peptide of full-length recombinant FXIII regulate activation rates by thrombin, and V34L influences in vivo thrombus formation by increased cross-linking of the clot.

Effect of Factor XIII-A G185T Polymorphism on Visual Prognosis after Photodynamic Therapy for Neovascular Macular Degeneration

Macular degenerations represent leading causes of central blindness or low vision in developed countries. Most of these severe visual disabilities are due to age-related macular degeneration (AMD) and pathologic myopia (PM), both of which are frequently complicated by subfoveal choroidal neovascularization (CNV). Photodynamic therapy with verteporfin (PDT-V) is still employed for CNV treatment in selected cases or in combined regimen. In Caucasian patients, the common polymorphism G185T of factor XIII-A gene (FXIII-A-G185T; rs5985) has been described as predictor of poor angiographic CNV responsiveness to PDT-V. Nevertheless, the prognostic implications of this pharmacogenetic determinant on long-term visual outcome after a PDT-V regimen have not been evaluated. We retrospectively selected Caucasian patients presenting with treatment-naive CNV and receiving standardized PDT-V protocol for two years. The study population included patients affected by subfoveal CNV secondary to AMD or PM. We assessed the correlations between the polymorphic allele T of FXIII-A-G185T and: (1) total number of photodynamic treatments; and (2) change in visual acuity from baseline to the end of the follow-up period. Considering a total study population of 412 patients with neovascular AMD or PM, the carriers of 185 T-allele of FXIII-A (GT or TT genotype) received a higher number of photodynamic treatments than patients without it (GG wild-type genotype) (p < 0.01; mean number of PDT-V: 5.51 vs. 3.76, respectively). Moreover, patients with 185 T-allele of FXIII-A had a more marked worsening of visual acuity at 24 months than those with the GG-185 wild genotype (p < 0.01; mean difference in logMAR visual acuity: 0.22 vs. 0.08, respectively). The present findings show that the G185T polymorphism of the FXIII-A gene is associated with significant differences in the long-term therapeutic outcomes of patients treated with standardized PDT-V protocol. The comprehensive appraisal of both anti-thrombophilic effects due to FXIII-A G185T variant and photo-thrombotic action of PDT-V toward CNV provides several clues about the rationale of this intriguing pharmacogenetic correlation. Further investigations are warranted to outline the appropriate paradigm for guiding PDT-V utilization in the course of the combined therapeutic protocol for neovascular macular degeneration.

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.

Coagulation factor XIII: a multifunctional transglutaminase with clinical potential in a range of conditions

Coagulation factor XIII (FXIII), a plasma transglutaminase, is best known as the final enzyme in the coagulation cascade, where it is responsible for cross-linking of fibrin. However, a growing body of evidence has demonstrated that FXIII targets a wide range of additional substrates that have important roles in health and disease. These include antifibrinolytic proteins, with cross-linking of α2-antiplasmin to fibrin, and potentially fibrinogen, being the principal mechanism(s) whereby plasmin-mediated clot degradation is minimised. FXIII also acts on endothelial cell VEGFR-2 and αvβ3 integrin, which ultimately leads to downregulation of the antiangiogenic protein thrombospondin-1, promoting angiogenesis and neovascularisation. Under infectious disease conditions, FXIII cross-links bacterial surface proteins to fibrinogen, resulting in immobilisation and killing, while during wound healing, FXIII induces cross-linking of the provisional matrix. The latter process has been shown to influence the interaction of leukocytes with the provisional extracellular matrix and promote wound healing. Through these actions, there are good rationales for evaluating the therapeutic potential of FXIII in diseases in which tissue repair is dysregulated or perturbed, including systemic sclerosis (scleroderma), invasive bacterial infections, and tissue repair, for instance healing of venous leg ulcers or myocardial injuries. Adequate levels of FXIII are also required in patients undergoing surgery to prevent or treat perioperative bleeding, and its augmentation in patients with/at risk for perioperative bleeding may also have potential clinical benefit. While there are preclinical and/or clinical data to support the use of FXIII in a range of settings, further clinical evaluation in these underexplored applications is warranted.

Clinical value of exogenous factor XIII for prolonged air leak following pulmonary lobectomy: a case control study

Background

We examined the effect of exogenous factor XIII (FXIII) concentrate in patients with prolonged air leak (PAL) after pulmonary lobectomy for non-small cell lung cancer.

Methods

We performed a retrospective analysis of 297 patients who underwent pulmonary lobectomy between July 2007 and March 2014: 90 had an air leak on the first postoperative day, which resolved spontaneously within 5 days in 53 cases (SR group). FXIII concentrate was administered to the remaining 37 patients (PAL group) for 5 days. This group was subdivided into those in whom the air leak resolved during FXIII treatment (EF group) and those who needed additional intervention (inEF group). The clinical and perioperative characteristics of the groups were compared.

Results

Although plasma FXIII activity did not differ significantly between the SR and PAL groups before surgery or on the fifth postoperative day, the proportional perioperative fall in FXIII activity was significantly greater in the SR group (33%) than the PAL group (22%, p = 0.044) and inEF group (14%, p = 0.048). On the fifth postoperative day, FXIII activity was significantly lower in the EF group than in the inEF group (74% versus 91%, p = 0.030). The optimal cut-off point for postoperative plasma FXIII activity to distinguish between the EF and inEF groups was 86%.

Conclusions

Insufficient plasma FXIII consumption and lower postoperative FXIII activity may play a role in the resolution of PAL, and exogenous FXIII concentrate may be an effective, safe and non-invasive treatment.

Coagulation factor XIII deficiency. Diagnosis, prevalence and management of inherited and acquired forms

The plasma circulating zymogenic coagulation factor XIII (FXIII) is a protransglutaminase, which upon activation by thrombin and calcium cross-links preformed fibrin clots/fibrinolytic inhibitors making them mechanically stable and less susceptible to fibrinolysis. The zymogenic plasma FXIII molecule is a heterotetramer composed of two catalytic FXIII-A and two protective FXIII-B subunits. Factor XIII deficiency resulting from inherited or acquired causes can result in pathological bleeding episodes. A diverse spectrum of mutations have been reported in the F13A1 and F13B genes which cause inherited severe FXIII deficiency. The inherited severe FXIII deficiency, which is a rare coagulation disorder with a prevalence of 1 in 4 million has been the prime focus of clinical and genetic investigations owing to the severity of the bleeding phenotype associated with it. Recently however, with a growing understanding into the pleiotropic roles of FXIII, the fairly frequent milder form of FXIII deficiency caused by heterozygous mutations has become one of the subjects of investigative research. The acquired form of FXIII deficiency is usually caused by generation of autoantibodies or hyperconsumption in other disease states such as disseminated intravascular coagulation. Here, we update the knowledge about the pathophysiology of factor XIII deficiency and its therapeutic options.

The perioperative course of factor XIII and associated chest tube drainage in newborn and infants undergoing cardiac surgery

BACKGROUND

Perioperative acquired factor XIII deficiency has been looked upon as a potential cause of postoperative bleeding in adult cardiac surgery.

METHODS

Forty-four infants were prospectively studied for the time course of factor XIII in plasma and the effect on chest tube drainage (CTD) and transfusion requirements in the first 24 h after surgery. A reconstituted blood prime (RBP) with fresh-frozen plasma (FFP) and packed red blood cells (PRBC) was used. Samples were taken at baseline, after cardiopulmonary bypass and upon arrival in the ICU. Differences in blood loss and transfusion requirements based on a cutoff value of 70% factor XIII activity at the time of ICU admission were also calculated.

RESULTS

Baseline factor XIII activity was 79%, decreased to 71% after CPB (P = 0.102) and increased back up to 77% at ICU arrival (P = 0.708). There was no significant correlation between factor XIII, CTD, age, cyanosis, platelet count, and transfusion requirements at any time point. Only preoperative fibrinogen levels correlated significantly with factor XIII activity. Perioperative blood transfusions (PRBC P = 0.712, FFP P = 0.909, platelets P = 0.807) and chest tube losses (P = 0.424 at 6 h and P = 0.215 at 24 h) were not significantly different above or below a 70% factor XIII activity at ICU arrival.

CONCLUSION

Factor XIII activity in infants with congenital heart defects is within the lower range of normal adults, independent of patient's age and the presence of cyanosis. Reconstituted blood prime maintains factor XIII activity at sufficient levels during pediatric cardiac surgery. We could not detect a correlation between FXIII and CTD.

Genetic association of five plasminogen activator inhibitor-1 (PAI-1) polymorphisms and idiopathic recurrent pregnancy loss in Korean women

Plasminogen activator inhibitor-1 (PAI-1) is important for maintaining pregnancy. Aberrantly increased PAI-1 levels may contribute to thrombosis and inflammation, leading to pregnancy loss. This study investigated the association of PAI-1 polymorphisms (PAI-1 rs2227631 [-844G>A], rs1799889 [-675 4G/5G], rs6092 [43G>A], rs2227694 [9785G>A], and rs7242 [11053T>G]) with idiopathic recurrent pregnancy loss (RPL) in Korean women. We screened 308 RPL patients and 227 control participants for five PAI-1 polymorphisms. Genotyping of PAI-1 was performed by polymerase chain reaction-restriction fragment length polymorphism assay. PAI-1 4G4G and -844AA/4G4G/11053GG genotypes were associated with RPL. PAI-1 -844A/4G/43G/9785G/11053G haplotype was connected to hypofibrinolytic status (i.e. increased levels of plasma PAI-1, increased numbers of platelets, reduced prothrombin time, and reduced activated partial thromboplastin time). Moreover, PAI-1 11053TG+GG frequency was positively related to plasma homocysteine and urate levels, whereas -844AA frequency was associated with plasma folate concentrations according to ordinal logistic regression analysis. Based on these results, we propose that PAI-1 -844G>A, 4G/5G, and 11053T>G polymorphisms are markers of RPL.

Polymorphism of transglutaminase 2: unusually low frequency of genomic variants with deficient functions

Transglutaminase 2 (TG2) is a multifunctional member of an enzyme family: it modifies glutamine residues by cross-linking proteins and incorporating primary amines into them, has protein disulphide isomerase and protein kinase activities, mediates trans-membrane signal transduction and interactions between cell surface proteins and the extracellular matrix. These unusual multiple roles encoded into one polypeptide chain suggest that genomic variations in the TGM2 gene should be limited. Indeed, the available information in databases shows that unlike in the case of most other transglutaminases there are no common single nucleotide polymorphisms in exons of human TGM2. We collected data on and produced some of the rare genetic variants of TGM2 by site directed mutagenesis and found that some were less stable than the most abundant (wild type) enzyme variant and the majority had deficient transamidating activity. Further studies are required to clarify the pathologic significance of these rare TGM2 alleles in the human population.

Factor XIII: a coagulation factor with multiple plasmatic and cellular functions

Factor XIII (FXIII) is unique among clotting factors for a number of reasons: 1) it is a protransglutaminase, which becomes activated in the last stage of coagulation; 2) it works on an insoluble substrate; 3) its potentially active subunit is also present in the cytoplasm of platelets, monocytes, monocyte-derived macrophages, dendritic cells, chondrocytes, osteoblasts, and osteocytes; and 4) in addition to its contribution to hemostasis, it has multiple extra- and intracellular functions. This review gives a general overview on the structure and activation of FXIII as well as on the biochemical function and downregulation of activated FXIII with emphasis on new developments in the last decade. New aspects of the traditional functions of FXIII, stabilization of fibrin clot, and protection of fibrin against fibrinolysis are summarized. The role of FXIII in maintaining pregnancy, its contribution to the wound healing process, and its proangiogenic function are reviewed in details. Special attention is given to new, less explored, but promising fields of FXIII research that include inhibition of vascular permeability, cardioprotection, and its role in cartilage and bone development. FXIII is also considered as an intracellular enzyme; a separate section is devoted to its intracellular activation, intracellular action, and involvement in platelet, monocyte/macrophage, and dendritic cell functions.

An update of the mutation profile of Factor 13 A and B genes

Mutational reports over the past two decades have accumulated an immense amount of literature for inherited Factor XIII deficiency. However, the genotype and phenotype correlations for inherited Factor XIII deficiency are complicated. While many studies clearly prove a cause and effect relationship for the reported mutations, others are lacking in this regard. The F13B gene remains an elusive component as far as inherited Factor XIII deficiencies are concerned. Also, an in-depth analysis into the heterozygous state of this deficiency is also lacking. In this review we have tried to analyze and present an exhaustive amount of mutational data from the past three decades. The source of our mutational data is our website dedicated to Factor XIII deficiencies (www.F13-database.de) as well as literature search done on the Pubmed (www.ncbi.nlm.nih.gov/pubmed).

Review: Interplay of Iron Metallobiology, Metalloproteinases, and FXIII, and Role of Their Gene Variants in Venous Leg Ulcer

The iron metallobiology has long been suspected as a causal agent in venous leg ulcer (VLU) pathophysiology. However, it was demonstrated only recently that visible iron deposits cause lesions in only some individuals due to functional iron and related gene variants. In this article, the mechanism by which dysregulated iron cycle leads to local iron overload that could generate free radicals or activate a proteolytic hyperactivity on the part of matrix metalloproteinases (MMPs) or else downregulate tissue inhibitors of MMPs is reviewed. Also reviewed is the interplay of other vital factors such as coagulation factor XIII (FXIII), which influences tissue remodeling and angiogenesis, leading to impaired healing of the lesion, whether there exists altered interaction with MMPs or in presence of particular unfavorable single nucleotide polymorphisms.

Mutations affecting disulphide bonds contribute to a fairly common prevalence of F13B gene defects: results of a genetic study in 14 families with factor XIII B deficiency

Severe factor XIII (FXIII) deficiency is a rare autosomal recessive coagulation disorder affecting one in two million individuals. The aim of the present study was to screen for and analyse F13B gene defects in the German population. A total of 150 patients presenting with suspected FXIII deficiency and one patient with severe (homozygous) FXIII deficiency were screened for mutations in F13A and F13B genes. Twenty-five individuals presented with detectable heterozygous mutations, 12 of them in the F13A gene and 13 of them in the F13B gene. We report on the genotype-phenotype correlations of the individuals showing defects in the F13B gene. Direct sequencing revealed 12 unique mutations including seven missense mutations (Cys5Arg, Ile81Asn, Leu116Phe, Val217Ile, Cys316Phe, Val401Glu, Pro428Ser), two splice site mutations (IVS2-1G>C, IVS3-1G>C), two insertions (c.1155_1158dupACTT, c.1959insT) and one in-frame deletion (c.471-473delATT). Two of the missense mutations (Cys5Arg, Cys316Phe) eliminated disulphide bonds (Cys5-Cys56, Cys316-Cys358). Another three missense mutations, (Leu116Phe, Val401Glu, Pro428Ser) were located proximal to other cysteine disulphide bonds, therefore indicating that the region in and around these disulphide bonds is prone to functionally relevant mutations in the FXIII-B subunit. The present study reports on a fairly common prevalence of F13B gene defects in the German population. The regions in and around the cysteine disulphide bonds in the FXIII-B protein may be regions prone to frequent mutations.

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.

Factor XIII deficiency

Inherited factor XIII (FXIII) deficiency is a rare bleeding disorder that can present with umbilical bleeding during the neonatal period, delayed soft tissue bruising, mucosal bleeding and life-threatening intracranial haemorrhage. FXIII deficiency has also been associated with poor wound healing and recurrent miscarriages. FXIII plays an integral role in haemostasis by catalysing the cross-linking of fibrin, platelet membrane and matrix proteins throughout thrombus formation, thus stabilizing the blood clot. The molecular basis of FXIII deficiency is characterized by a high degree of heterogeneity, which contributes to the different clinical manifestations of the disease. There have been more than 60 FXIII mutations identified in the current literature. In addition, single nucleotide polymorphisms have been described, some of which have been shown to affect FXIII activity, contributing further to the heterogeneity in patient presentation and severity of clinical symptoms. Although there is a lifelong risk of bleeding, the prognosis is excellent when current prophylactic treatment is available using cryoprecipitate or plasma-derived FXIII concentrate.

Cardiovascular disease and heritability of the prothrombotic state

Atherothrombotic disease remains a major cause of mortality worldwide, and family clustering suggests an important contribution of genetic factors to disease pathogenesis. Thrombus formation represents the final step in atherothrombosis, a process influenced by genetic and environmental factors. A major difficulty of investigating the genetic regulation of thrombotic conditions is the complexity of the phenotype and the relatively modest effects of individual genetic variations. We address in this review genetic aspects involved in regulating thrombosis potential and their impact on the development of atherothrombotic disease. The effects of common genetic polymorphisms in clotting factors are discussed and examples of complex gene-gene and gene-environment interactions are highlighted. Understanding the effects of genetic factors on predisposition to thrombotic disease and unravelling the complex gene-environment interactions will help to better understand the pathophysiology of this complex condition, which will enable the development of new preventative and treatment strategies.

Coagulation factor XIII gene variation, oral contraceptives, and risk of ischemic stroke

Prothrombotic conditions are associated with ischemic stroke in young women. In particular, the combination of oral contraceptive use and prothrombotic genetic variants appears to increase the risk of ischemic stroke. We performed a population-based case-control study in 190 women aged 20 to 49 years with ischemic stroke and 767 women without cardiovascular disease stratified for age, calendar year of the index event, and residence. A total of 4 variants of coagulation factor XIII subunit A and B genes (F13A1 and F13B) were investigated. The Phe allele of the F13A1 Tyr204Phe variant was present in 59 (31%) patients and 43 (6%) controls; the odds ratio for ischemic stroke was 9.1 for Phe/Phe and Phe/Tyr versus Tyr/Tyr genotype; the 95% confidence interval was 5.5 to 15. Homozygous genotypes (Phe/Phe) conferred a higher risk (odds ratio, 77; 95% confidence interval, 7.0-848) than heterozygous (Tyr/Phe) genotypes (odds ratio, 8.2; 95% confidence interval, 4.9-14). The risk of ischemic stroke was further increased in carriers of the 204Phe allele using oral contraceptives (odds ratio, 20; 95% confidence interval, 9-46) compared with nonusers with Tyr/Tyr genotype. In conclusion, the F13A1 204Phe allele was strongly associated with ischemic stroke in young women. Oral contraceptive use further increased the risk of ischemic stroke.

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.

Factor XIIIA-V34L and factor XIIIB-H95R gene variants: effects on survival in myocardial infarction patients

It has been demonstrated recently that coagulation factor XIII (FXIII) plays an extraordinary role in myocardial healing after infarction, improving survival in a mouse model. Common FXIII gene variants (i.e. FXIIIA-V34L and FXIIIB-H95R) significantly influence the molecular activity. To evaluate whether there is a relationship between the two FXIII gene variants and survival in patients after myocardial infarction (MI), V34L and H95R were PCR-genotyped in a cohort of 560 MI cases and follow-up was monitored. Cases with ST-segment elevation MI (STEMI) were 416 (74.3%) and 374 of these were treated with primary percutaneous coronary intervention (PCI) (89.9%). The remaining 144 patients showed non-ST-segment elevation MI (NSTEMI) at enrollment. The combined endpoint was the occurrence of death, re-infarction, and heart failure. Kaplan-Meier analysis at one year yielded an overall rate for adverse events of 24.5% with a lower incidence in the L34-carriers (28.8% vs 17.1%; log-rank, P = 0.00025), similar to that of the 416 STEMI (23.8%) being (28.0% and 16.9%; VV34- and L34-carriers respectively; log-rank, P = 0.001). Primary PCI-group had a slight lower incidence (22.9%) of adverse events (26.8% and 17.1%; VV34- and L34-carriers respectively; log-rank, P = 0.009). During hospitalization, 506 patients received PCI (374 primary PCI and 132 elective PCI). Significance was conserved also in the overall PCI-group (28.6% and 17.8%; VV34- and L34-carriers respectively; log-rank, P = 0.001). Similar findings were observed at 30 days follow-up. Cases carrying both FXIII variants had improved survival rate (log-rank, P = 0.019). On the other hand, minor bleeding complications were found increased in L34-carriers (P = 0.0001) whereas major bleeding complications were not. Finally, more direct evidence on the role of FXIII molecule on survival might come from the fact that despite significant FXIII antigen reductions observed in cases after MI, regardless the FXIII genotype considered, L34-carriers kept almost normal FXIII activity (VV34- vs L34-carriers; P < 0.001). We conclude that FXIII L34-allele improves survival after MI in all the groups analyzed, possibly through its higher activity associated with assumable positive effects on myocardial healing and recovered functions. Genetically determined higher FXIII activity might influence post-MI outcome. This paves the way for using FXIII molecules to improve myocardial healing, recovery of functions, and survival after infarction.

Recurrent pregnancy loss: the key potential mechanisms

Recurrent pregnancy loss (RPL), which occurs in 0.5%-1% of total pregnancies, is usually defined as three or more consecutive spontaneous abortions before 20 weeks of gestation. Although an immunology-based etiology underlying unexplained RPL has been demonstrated, the exact molecular mechanisms are still poorly understood. Recent studies using transcriptomics and proteomics have implicated several factors. Here, we review the key possible mechanisms, in particular immunological abnormalities and thrombophilic aberration, that might underlie RPL. Taken together, these findings provide insight into the development of effective therapeutics for RPL.

Fibrinolytic defects and recurrent miscarriage: a systematic review and meta-analysis

OBJECTIVE

To systematically review evidence of the association between fibrinolytic defects and recurrent miscarriage.

DATA SOURCES

MEDLINE, EMBASE, and references of retrieved articles (last update September 2006) were used.

METHODS OF STUDY SELECTION

Studies comparing the prevalence of fibrinolytic defects in patients with recurrent miscarriage and control women were reviewed. Of 111 potentially relevant studies, data from 14 were integrated with meta-analytic techniques and were presented as odds ratios (ORs).

TABULATION, INTEGRATION, AND RESULTS

Plasminogen activator inhibitor-1 4G/5G polymorphism (OR 1.65, 95% confidence interval [CI] 0.92-2.95) and increased plasminogen activator inhibitor activity were not significantly associated with recurrent miscarriage, although the latter showed profound heterogeneity across studies. Although factor XII C46T polymorphism is not associated with recurrent miscarriage (OR 1.07, 95% CI 0.52-2.22), factor XII deficiency is significantly associated (five studies, 1,096 women; OR 18.11, 95% CI 5.52-59.39), with minimal heterogeneity across studies. Factor XIII Val34Leu and Tyr204Phe polymorphisms were not associated with recurrent miscarriage (OR 1.24, 95% CI 0.46-3.34 and OR 2.61, 95% CI 0.45-15.16, respectively). There were no eligible studies found for the rest of the factors searched (urokinase-type plasminogen activator, tissue-type plasminogen activator, kallicrein, a2-antiplasmin, a2-macroglobulin, thrombin-activated thrombolysis inhibitor, and factor XI). Only a small minority of studies ascertained miscarriage according to specific criteria, and none of the studies provided equal examination for confounders in cases and controls.

CONCLUSION

Factor XII deficiency is associated with recurrent miscarriage. Data on the other factors either fail to show association or are quite limited.

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.