Localization of the coagulation factor XIII A subunit gene (F13A) to chromosome bands 6p24----p25

The Usefulness of Factor XIII Concentration Assessment in Patients in the Acute Phase of Ischaemic Stroke Treated with Thrombolysis

BACKGROUND AND AIMS

In recent years, there has been a growing interest in factor XIII in ischaemic stroke. The study's main aim was to assess the usefulness of factor XIII concentration determination in patients with acute ischaemic stroke (AIS) treated with thrombolysis with recombinant tissue plasminogen activator (t-PA).

METHODS

The study was conducted in two groups of 84 patients with AIS: group I-with thrombolytic therapy and group II-without thrombolysis. A physical examination, neurological status (using the National Institutes of Health Stroke Scale, NIHSS), daily patients' activities measured with the Barthel Index and Modified Rankin Scale (mRS), and blood parameters were conducted on day 1 and day 7. The following parameters were assessed: highly sensitive C-reaction protein (CRP), fibrinogen, D-dimers (DD), neutrophil-lymphocyte ratio (NLR index), and the concentration of factor XIII-A.

RESULTS

In group I, the concentration of XIII-A decreased significantly between day 1 and 7 (p < 0.001). In group I, the concentration of XIII-A on day 7 in Total Anterior Circulation Infarct (TACI) was significantly lower than in non-TACI stroke. XIII-A concentration in group I was significantly lower in patients < 31 points with Acute Stroke Registry and Analysis of Lausanne (ASTRAL). A greater decrease in XIII-A between the first sampling on day 1 and the second sampling on day 7 was associated with a worse patient neurological state in group I.

CONCLUSIONS

In patients with AIS treated with t-PA, factor XIII concentrations decrease in the acute phase of stroke, and the largest decrease occurs in the TACI stroke. Determination of factor XIII concentration in patients with AIS can be used in clinical practice as an additional parameter supporting the assessment of stroke severity and may play a role in the prognosis; lower factor XIII-A activity may be a predictor of a worse prognosis.

Dental Management of Factor XIII Deficiency Patients: A Case Series

Aim

To create awareness about rare clotting disorders in children and to highlight the different dental treatment approaches that can be used while planning the management in such cases.

Background

A prerequisite for successful wound healing is achieving good hemostasis by effective vascular spasm, platelet plug formation, and finally blood coagulation. In the general population, postoperative bleeding after dental treatment is self-limiting. However, a certain segment of the population does suffer from inherited bleeding and clotting disorders, where in standard invasive dental procedures can trigger bleeding episodes, which could be life-threatening in absence of the requisite precautionary measures being followed.

Case description

One such condition is congenital factor XIII deficiency, a rare autosomal recessive disease usually associated with early onset of serious or life-threatening bleeding episodes, such as, intracranial hemorrhage or umbilical cord bleeding. This case series details the complete dental management of three children suffering from factor XIII deficiency.

Conclusion

Factor XIII is a rare coagulation cascade, and by this case series, complete dental treatment varying from noninvasive to be kept under observation to invasive dental extraction and fracture reduction was carried out with the hematologists consultations.

Clinical significance

This case series creates awareness about this rare condition and the need for a multidisciplinary approach involving dentists and hematologists in the effective management of such patients.

How to cite this article

Pai NG, Mehta LK, Padhye NM, et al. Dental Management of Factor XIII Deficiency Patients: A Case Series. Int J Clin Pediatr Dent 2020;XX(X):1–4.

Characterization of a novel large deletion caused by double-stranded breaks in 6-bp microhomologous sequences of intron 11 and 12 of the F13A1 gene

Coagulation Factor XIII is a heterotetrameric protransglutaminase which stabilizes preformed fibrin clots by covalent crosslinking them. Inherited homozygous or compound heterozygous deficiency of coagulation Factor XIII (FXIII) is a rare severe bleeding disorder affecting 1 in 2 million individuals. Most of the patients with inherited FXIII deficiency described in the literature carry F13A1 gene point mutations (missense, nonsense and splice site defects), whereas large deletions (>0.5 kb in size) are underrepresented. In this article we report for the first time the complete characterization of a novel homozygous F13A1 large deletion covering the entire exon 12 in a young patient with a severe FXIII-deficient phenotype from France. Using primer walking on genomic DNA we have identified the deletion breakpoints in the region between g.6.143,016–g.6.148,901 caused by small 6-bp microhomologies at the 5´ and 3´ breakpoints. Parents of the patient were heterozygous carriers. Identification of this large deletion offers the possibility of prenatal diagnosis for the mother in this family who is heterozygous for this deletion.

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.

Genetic association between FXIII and β-fibrinogen genes and women with recurrent spontaneous abortion: a meta- analysis

BACKGROUND

FXIII Val34Leu (rs5985) and β-fibrinogen -455G/A (rs1800790) genotypes have been reported to be associated with recurrent spontaneous abortion (RSA). However, this topic is controversial. This study aimed to explore whether FXIII Val34Leu or β-fibrinogen -455G/A gene polymorphisms are related to RSA.

METHODS

In this analysis, PubMed, HuGENet and Chinese National Knowledge Infrastructure (CNKI) databases were reviewed. Four models including the dominant model (Val/Val+Val/Leu vs. Leu/Leu), recessive model (Val/Val vs Val/Leu + Leu/Leu), co-dominant model (Val/Val vs. Val/Leu, Val/Val vs. Leu/Leu) and per-allele analysis (Val vs. Leu) were applied. The odds ratio (OR) with 95% confidence interval (CI) was used to assess the association between RSA and FXIII Val34Leu and β-fibrinogen -455G/A polymorphisms.

RESULTS

Nine studies with 10 sets of data were included according to the inclusion criterion. A positive association was detected in the pooled results for the dominant model (Val/Val+Val/Leu vs. Leu/Leu; OR = 0.417, 95% CI: 0.180-0.965, I(2) = 45.60%) and co-dominant model (Val/Val vs. Val/Leu; OR = 0.638, 95% CI: 0.452-0.899, I(2) = 36.40%) for FXIII Val34Leu polymorphisms. However, no statistically significant association between β-fibrinogen -455G/A polymorphisms and RSA was detected in the four different models, including the Asian and Caucasian subgroup analyses.

CONCLUSIONS

Our meta-analysis demonstrates that the FXIII Val34Leu polymorphism has a close association with RSA and women who carry the Val allele for the FXIII Val34Leu polymorphism could have a protective effect against RSA. However, no association is detected between β-fibrinogen -455G/A polymorphisms and the risk of RSA. Future well-designed studies are needed to confirm these results.

New developments in the management of congenital Factor XIII deficiency

Congenital Factor XIII (FXIII) deficiency is a rare, inherited, autosomal recessive coagulation disorder. Most mutations of this condition are found in the A-subunit with almost half these being missense mutations. Globally, approximately one in three million people suffer from this deficiency. Factor XIII deficiency is associated with severe life threatening bleeding, intracranial hemorrhage, impaired wound healing, and recurrent pregnancy losses. FXIII is known to have a potential role in mediating inflammatory processes, insulin resistance, bone metabolism, neoplasia, and angiogenesis. The algorithm provided for FXIII diagnosis and classification will enable prompt identification and early intervention for controlling potential life threatening complications. Prophylactic replacement therapy using blood products containing FXIII such as fresh frozen plasma, cryoprecipitate, or using FXIII concentrate remains the mainstay for the management of FXIII deficiency. In most parts of the world, cryoprecipitate and plasma transfusions are the only treatments available. Management developments have revealed the effectiveness and safety of recombinant FXIII concentrate for prophylaxis and treatment. The aim of this review is to provide an overview of advancements made in the management of FXIII deficiency from the time it was first detected, highlighting novel developments made in recent years. Greater research is warranted in identifying novel approaches to manage FXIII deficiency in light of its underlying pathophysiology.

Genetic markers of cardiovascular disease in rheumatoid arthritis

Cardiovascular (CV) disease is the most common cause of premature mortality in patients with rheumatoid arthritis (RA). It is the result of an accelerated atherosclerotic process. Both RA and atherosclerosis are complex polygenic diseases. Besides traditional CV risk factors and chronic inflammation, a number of studies have confirmed the role of genetic factors in the development of the atherogenesis observed in RA. In this regard, besides a strong association between the HLA-DRB1∗04 shared epitope alleles and both endothelial dysfunction, an early step in the atherosclerotic process, and clinically evident CV disease, other polymorphisms belonging to genes implicated in inflammatory and metabolic pathways, located inside and outside the HLA region, such as the 308 variant (G > A, rs1800629) of the TNFA locus, the rs1801131 polymorphism (A > C; position + 1298) of the MTHFR locus, or a deletion of 32 base pairs on the CCR5 gene, seem to be associated with the risk of CV disease in patients with RA. Despite considerable effort to decipher the genetic basis of CV disease in RA, further studies are required to better establish the genetic influence in the increased risk of CV events observed in patients with RA.

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.

Characterization of the transglutaminase gene family in zebrafish and in vivo analysis of transglutaminase-dependent bone mineralization

We have characterized the protein cross-linking enzyme transglutaminase (TGs) genes in zebrafish, Danio rerio, based on the analysis of their genomic organization and phylogenetics. Thirteen zebrafish TG genes (zTGs) have been identified, of which 11 show high homology to only 3 mammalian enzymes: TG1, TG2 and FXIIIa. No zebrafish homologues were identified for mammalian TGs 3-7. Real-time PCR analysis demonstrated distinct temporal expression profiles for zTGs in larvae and adult fish. Analysis by in situ hybridization revealed restricted expression of zTG2b and zFXIIIa in skeletal elements, resembling expression of their mammalian homologues in osteo-chondrogenic cells. Mammalian TG2 and FXIIIa have been implicated in promoting osteoblast differentiation and bone mineralization in vitro, however, mouse models lacking either gene have no skeletal phenotype likely due to a compensation effect. We show in this study that mineralization of the newly formed vertebrae is significantly reduced in fish grown for 5 days in the presence of TG inhibitor KCC-009 added at 3-5 days post fertilization. This treatment reduces average vertebrae mineralization by 30%, with complete inhibition in some fish, and no effect on the overall growth and vertebrae number. This is the first in vivo demonstration of the crucial requirement for the TG-catalyzed cross-linking activity in bone mineralization.

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.

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.

Factor XIII gene V34L mutation in the Lebanese population: Another unique feature in this community?

We studied the distribution of the Factor XIII gene V34L polymorphism in a sample of healthy Lebanese individuals to assess its prevalence and compare it with other populations. Factor XIII genotypes were determined using the Cardiovascular Disease (CVD) StripAssay (ViennaLab, Austria), which is based on a Polymerase Chain Reaction-Reverse hybridization technique. DNA from 205 unrelated healthy donors from our HLA database was used. The prevalence of Wild type, heterozygous, and homozygous genotypes was found to be 74.2%, 22.4%, and 3.4% respectively. The sampled Lebanese population showed that the prevalence of V34L carriers (25.8%) was lower than Caucasians in general (44.3%) and, interestingly, with a low allele frequency of 0.14 similar to that in Blacks and South Asians. This first report from Lebanon sheds light on an additional unique genetic feature of this population and will prospectively serve as a baseline statistical data for future investigations of the prevalence of Factor XIII V34L mutation in association with various clinical entities notably cardiovascular diseases.

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.

Effect of four missense mutations in the factor XIII A-subunit gene on protein stability: studies with recombinant proteins

Four missense mutations in the factor XIII A-subunit gene, Arg260Leu, Ala318Val, Thr398Asn and Gly210Arg, were previously reported by us in patients with severe factor XIII deficiency. The objective of our study was to discern the effect of all four mutations on the stability and intracellular localization of the factor XIII A-subunit by their expression in COS cells. In-vitro mutagenesis, transient expression of the mutants in COS cells and subsequent pulse-chase analyses were carried out. Intracellular localization of wild-type and mutant proteins was analyzed by immunohistochemistry using a monoclonal antibody against factor XIII A-subunit. Pulse-chase analyses of metabolically labeled proteins demonstrated rapid intracellular degradation of each mutant protein as compared with wild type. Immunocytochemical and immunofluorescence analyses disclosed that wild-type and all four mutant factor XIII A-subunit proteins were diffusely distributed within the cytoplasm but not in the endoplasmic reticulum of the COS-7 cells. The Arg260Leu, Ala318Val, Thr398Asn and Gly210Arg mutations in FXIII A-subunit cause rapid intracellular degradation of the corresponding mutated protein.

Congenital deficiency of factor XIII caused by two missense mutations in a Dutch family

We present the clinical, biochemical and genomic findings of a family with congenital factor XIII (FXIII) deficiency. Congenital FXIII deficiency is a very rare autosomal recessive bleeding disorder, characterized by umbilical cord bleeding at birth and spontaneous intracranial haemorrhage. Routine clotting tests are normal, which may delay the diagnosis, leading to an increased chance of severe sequelae. The propositus and her brother, known with haemorrhagic diathesis, were found to be compound heterozygous with a known missense mutation (1050 G --> T transversion in exon 7, Val316Phe substitution) and a novel mutation 889 G --> A in exon 6, which predicts a Gly262Glu substitution. As these mutations were known in the family, DNA obtained from cord blood of the youngest sister was analysed for mutations in exons 6 and 7 only. We postulate that the diagnosis was facilitated by determining the two different mutations in the genotype of this family. The analysis showed that she was heterozygous for the exon 7 mutation. Hence, she was not at risk of experiencing haemorrhagic diathesis. This diagnosis avoided the administration of FXIII concentrate to the newborn.

Seven novel mutations in the factor XIII A-subunit gene causing hereditary factor XIII deficiency in 10 unrelated families

BACKGROUND

Hereditary factor (F)XIII deficiency is a rare bleeding disorder mostly due to mutations in FXIII A subunit.

OBJECTIVES

We studied the molecular basis of FXIII deficiency in patients from 10 unrelated families originating from Israel, India and Tunisia.

METHODS

Exons 2-15 of genomic DNA consisting of coding regions and intron/exon boundaries were amplified and sequenced. Structural analysis of the mutations was undertaken by computer modeling.

RESULTS

Seven novel mutations were identified in the FXIIIA gene. The propositus from the Ethiopian-Jewish family was found to be a compound heterozygote for two novel mutations: a 10-bp deletion in exon 12 at nucleotides 1652-1661 (followed by 22 altered amino acids and termination codon) and Ala318Val mutation. The propositus of the Tunisian family was homozygous for C insertion after nucleotide 863 within a stretch of six cytosines of exon 7. This insertion results in generation of eight altered amino acids followed by a termination codon downstream. The propositus from Indian-Jewish origin was found to be homozygous for G to T substitution at IVS 11 [+1] resulting in skipping of exons 10 and 11. In addition to the Ala318Val mutation, three of the novel mutations identified are missense mutations: Arg260Leu, Thr398Asn and Gly210Arg each occurring in a homozygous state in an Israeli-Arab and two Indian families, respectively.

CONCLUSIONS

Structure-function correlation analysis by computer modeling of the new missense mutations predicted that Gly210Arg will cause protein misfolding, Ala318Val and Thr398Asn will interfere with the catalytic process or protein stability, and Arg260Leu will impair dimerization.

Identification of an inframe deletion and a missense mutation in the factor XIIIA gene in two Turkish patients

We report two novel mutations in factor XIIIA (FXIIIA) gene that caused congenital factor XIII deficiency in two unrelated patients. The first alteration, a missense mutation Leu235Arg in exon 6 of FXIIIA gene, is located in the putative calcium-binding part of the core domain of the enzyme. Replacement of non-polar hydrophobic leucine residue with positively charged arginine residue is likely to effect protein folding thus destabilizing the molecule. The second mutation is a 3-bp deletion in exon 14 of FXIIIA gene. This deletion is located in beta barrel 2 domain of the protein and results in translation of an aberrant FXIIIA molecule that lacks lysine residue either at positions 677 or 678. As this inframe deletion is located in a direct repetetive sequence of AAGAAG, that codes for two lysine residues, the exact location of deletion could not be detected.

Role of factor XIII in fibrin clot formation and effects of genetic polymorphisms

Factor XIII and fibrinogen are unusual among clotting factors in that neither is a serine protease. Fibrin is the main protein constituent of the blood clot, which is stabilized by factor XIIIa through an amide or isopeptide bond that ligates adjacent fibrin monomers. Many of the structural and functional features of factor XIII and fibrin(ogen) have been elucidated by protein and gene analysis, site-directed mutagenesis, and x-ray crystallography. However, some of the molecular aspects involved in the complex processes of insoluble fibrin formation in vivo and in vitro remain unresolved. The findings of a relationship between fibrinogen, factor XIII, and cardiovascular or other thrombotic disorders have focused much attention on these 2 proteins. Of particular interest are associations between common variations in the genes of factor XIII and altered risk profiles for thrombosis. Although there is much debate regarding these observations, the implications for our understanding of clot formation and therapeutic intervention may be of major importance. In this review, we have summarized recent findings on the structure and function of factor XIII. This is followed by a review of the effects of genetic polymorphisms on protein structure/function and their relationship to disease.

Mutations in coagulation factor XIII A gene in three Turkish patients: two novel mutations and a known insertion

Molecular analysis of factor XIII A gene on three unrelated Turkish families identified two novel and one known mutations. One novel mutation is a substitution of cytidine by guanine at codon 541 in exon 12, beta barrel 1 domain of the coagulation factor XIII A subunit gene resulting in the conversion of asparagine to lysine. The mutation alters the restriction site of the enzyme MboII. The second novel mutation, a 4 bp (-CAAA) deletion located in a direct repetitive sequence (CAAACAAA) between codons 466-469, results in premature termination of translation at codon 474. The third mutation is a previously reported single nucleotide (cytidine) insertion at codon 400 in exon 9 of the factor XIII gene.

Evolution of transglutaminase genes: identification of a transglutaminase gene cluster on human chromosome 15q15. Structure of the gene encoding transglutaminase X and a novel gene family member, transglutaminase Z

We isolated and characterized the gene encoding human transglutaminase (TG)(X) (TGM5) and mapped it to the 15q15.2 region of chromosome 15 by fluorescence in situ hybridization. The gene consists of 13 exons separated by 12 introns and spans about 35 kilobases. Further sequence analysis and mapping showed that this locus contained three transglutaminase genes arranged in tandem: EPB42 (band 4.2 protein), TGM5, and a novel gene (TGM7). A full-length cDNA for the novel transglutaminase (TG(Z)) was obtained by anchored polymerase chain reaction. The deduced amino acid sequence encoded a protein with 710 amino acids and a molecular mass of 80 kDa. Northern blotting showed that the three genes are differentially expressed in human tissues. Band 4.2 protein expression was associated with hematopoiesis, whereas TG(X) and TG(Z) showed widespread expression in different tissues. Interestingly, the chromosomal segment containing the human TGM5, TGM7, and EPB42 genes and the segment containing the genes encoding TG(C),TG(E), and another novel gene (TGM6) on chromosome 20q11 are in mouse all found on distal chromosome 2 as determined by radiation hybrid mapping. This finding suggests that in evolution these six genes arose from local duplication of a single gene and subsequent redistribution to two distinct chromosomes in the human genome.

Two novel and one recurrent missense mutation in the factor XIII A gene in two Dutch patients with factor XIII deficiency

Congenital factor XIII (FXIII) deficiency is a rare autosomal recessive disorder, usually attributed to a defect in the FXIII A subunit, whose genetic basis has been studied in a number of cases. We describe here the genetic variations found in two unrelated patients with FXIII deficiency. Both patients, under prophylactic substitution with FXIII concentrate, showed low plasma FXIII A subunit antigen levels with undetectable A subunit antigen in the platelets and normal plasma B antigen levels, which indicate that the defects are present in the A subunit of the molecule. Both probands were heterozygous for a previously reported G-->A transversion in exon 8 of the FXIII A subunit gene (Arg326Gln substitution). Proband 1 was also heterozygous for a novel G-->T transversion in exon 7, which predicts a Val316Phe substitution. Two of her sons were heterozygous for this mutation and showed low FXIII activity and FXIII A subunit antigen levels. Val316 is a well-conserved amino acid among the transglutaminase family, located within the core domain, close to the Cys314 member of the catalytic triad. Proband 2 had a unique 2-bp (TT) insertion in one of the alleles within or adjacent to the -7 to -20 T tail of intron A. This insertion was not found in 50 healthy individuals, which supports this being the second mutation in this patient.

Racial and genetic determinants of plasma factor XIII activity

Factor XIII (F XIII), a plasma transglutaminase, is essential for normal hemostasis and fibrinolysis. Plasma F XIII consists of two catalytic A (F XIIIA) and two non-catalytic B (F XIIIB) subunits. Activated F XIII is involved in the formation of fibrin gel by covalently crosslinking fibrin monomers. As the characteristics of the fibrin gel structure have been shown to be associated with the risk of coronary heart disease (CHD), F XIII activity may play a seminal role in its etiology. In this investigation, we determined plasma F XIII activity in two racial groups, including Asian Indians (n = 258) and Chinese (n = 385). Adjusted plasma F XIII activity was significantly higher in Indian men (142 vs. 110%; P<0.0001) and women (158 vs. 111%; P<0.0001) than their Chinese counterparts. As compared to Indians where the distribution of F XIII activity was almost normal, in Chinese it was skewed towards low activity. In both racial groups, bivariate and multivariate analyses showed strong correlation of F XIII activity with plasma fibrinogen and plasminogen levels. Race explained about 25% of the variation in F XIII activity even after the adjustment of significant correlates. We also determined the contribution of common genetic polymorphisms in the F XIIIA and F XIIIB genes in affecting plasma F XIII activity. Both loci showed significant and independent effects on plasma F XIII activity in Indians (F XIIIA, P< 0.01; F XIIIB, P<0.05) and Chinese (F XIIIA, P<0.0001; F XIIIB, P<0.13) in a gene dosage fashion. This study shows that both racial and genetic components play a significant role in determining plasma F XIII activity, and consequently it may affect the quantitative risk of CHD.

A complete deficiency of coagulation factor XIII A-subunit due to a novel compound heterozygote of Ser 413 Leu missense and an nt 389 (ins G) frameshift mutation

Coagulation factor XIII consists of two A- and two B-subunits, and either gene mutation can cause a complete deficiency. In a newborn patient with persistent bleeding from the umbilical cord stump, the plasma A-subunit protein was not detectable. Direct PCR sequencing revealed an nt 389 (ins G) frameshift mutation in exon 4 resulting in a new stop codon and a Ser 413 Leu missense mutation in exon 10 in either allele. His mother and father were heterozygous for the nt 389 (ins G) and the Ser 413 Leu, respectively, with about 50% reduction of the plasma A-subunit proteins. In all family members examined only those with either mutation showed the reduced subunit A protein levels. Thus, this complete deficiency of factor XIII was due to a novel compound heterozygous mutation in the A-subunit gene.

Organization and chromosomal mapping of mouse Gh/tissue transglutaminase gene (Tgm2)

The mouse Gh/tissue transglutaminase gene (Tgm2), coding a dual-function protein that both binds guanosine triphosphate (GTP) and catalyzes the posttranslational modification of proteins by transamidation of glutamine residues, has been cloned. Sequence analysis of Tgm2 and comparison with the TGase sequences of other species allowed correction of several apparent sequencing artifacts in the Tgm2 cDNA. Tgm2 spans approximately 34 kb and has 13 exons and 12 introns. Although the structure of Tgm2 shows similarity to that of other transglutaminase genes, with introns ranging from 921 bp to >5 kb, several introns differ considerably in size from those of the human Gh gene, TGM2. Tgm2 maps to the distal region of mouse chromosome 2, a region syntenic to human chromosome 20q containing TGM2. Tgm2 is in the vicinity of two uncloned mouse mutations, diminutive (dm) and blind-sterile (bs). Genomic DNA from dm mice was unavailable; however, Southern blot analysis of bs DNA showed no gross rearrangements of Tgm2.

Transcriptional regulation of cell type-specific expression of the TATA-less A subunit gene for human coagulation factor XIII

To study the mechanism of gene regulation for coagulation factor XIII A subunit (FXIIIA), we characterized its 5'-flanking region using a monocytoid (U937), a megakaryocytoid (MEG-01), and other cells. Our results confirmed that U937 and MEG-01 contained FXIIIA mRNA. A tentative transcription start site was determined to be 76 bases upstream from the first exon/intron boundary. Reporter gene assays revealed that a 5'-fragment (-2331 to +75) was sufficient to support basal expression in U937 and MEG-01 but not in the other cells. Deletion analysis confined a minimal promoter sequence from -114 to +75. DNase footprinting, electrophoretic mobility shift, and reporter gene assays demonstrated that promoter elements for a myeloid-enriched transcription factor (MZF-1-like protein) and two ubiquitous transcription factors (NF-1 and SP-1) in this region were important for the basal FXIII expression. It was also revealed that an upstream region (-806 to -290) had enhancer activity in MEG-01 but silencer activity in U937. DNA sequences for binding of myeloid-enriched factors (GATA-1 and Ets-1) were recognized in this region, and the GATA-1 element was found to be responsible for the enhancer activity. These transcription factors play a major role in the cell type-specific expression of FXIIIA, which differs from other transglutaminases.

Structural characterization and chromosomal localization of the gene encoding human biphenyl hydrolase-related protein (BPHL)

The gene encoding human biphenyl hydrolase-related protein (Bph-rp), a serine hydrolase with sequence similarity to prokaryotic enzymes involved in the degradation of polychlorinated biphenyls, has been cloned and its overall organization established. The gene, whose HGM-approved nomenclature is BPHL, spans more than 30 kb and is composed of eight exons and seven introns. The number and distribution of exons and introns differ from those reported for the genes encoding other serine hydrolases with sequence similarity to Bph-rp, indicating that these genes are distantly related. Nucleotide sequence analysis of the 5'-flanking region of BPHL revealed a high GC content, a ratio CpG/GpC close to unity, and the absence of consensus transcriptional sequences such as a TATA box or a CCAAT box. Chromosomal localization of BPHL revealed that it maps to chromosome 6p25, a unique location for all serine hydrolases mapped to date.

A Novel Asn344 Deletion in the Core Domain of Coagulation Factor XIII A Subunit: Its Effects on Protein Structure and Function

In this study a previously undescribed 3 bp deletion, AAT1030-1032, in the factor XIII A subunit gene, has been detected in a Thai patient. The inframe deletion results in the translation of a factor XIII A subunit that lacks Asn344. This is the first inframe deletion to be identified in the factor XIII A subunit gene because six previously reported deletions have all caused frameshifts. The deletion has been introduced into a factor XIII A subunit cDNA and the deleted polypeptide expressed in yeast. The mRNA encoding the mutant enzyme appears to have normal stability but the translated protein is subject to premature degradation. In addition, the mutated enzyme exhibited very little transglutaminase activity compared with the wild-type enzyme. Structural modeling of the deleted enzyme suggests that the absence of Asn344 would have a potent impact on the catalytic activity by reorienting the residues associated with the catalytic center. Thus, the Asn344 deletion strongly confirms the significance of the residues surrounding the catalytic center of the factor XIII A subunit.

A Novel Asn344 Deletion in the Core Domain of Coagulation Factor XIII A Subunit: Its Effects on Protein Structure and Function

In this study a previously undescribed 3 bp deletion, AAT1030-1032, in the factor XIII A subunit gene, has been detected in a Thai patient. The inframe deletion results in the translation of a factor XIII A subunit that lacks Asn344. This is the first inframe deletion to be identified in the factor XIII A subunit gene because six previously reported deletions have all caused frameshifts. The deletion has been introduced into a factor XIII A subunit cDNA and the deleted polypeptide expressed in yeast. The mRNA encoding the mutant enzyme appears to have normal stability but the translated protein is subject to premature degradation. In addition, the mutated enzyme exhibited very little transglutaminase activity compared with the wild-type enzyme. Structural modeling of the deleted enzyme suggests that the absence of Asn344 would have a potent impact on the catalytic activity by reorienting the residues associated with the catalytic center. Thus, the Asn344 deletion strongly confirms the significance of the residues surrounding the catalytic center of the factor XIII A subunit.

Arg260-Cys mutation in severe factor XIII deficiency: conformational change of the A subunit is predicted by molecular modelling and mechanics

To explore the implications of the structure/ function relationships in factor XIII. a patient with severe A subunit deficiency was examined at the DNA and RNA levels. Nucleotide sequence analysis of the patient's DNA amplified by PCR revealed that the patient had a replacement of C by T in the codon for Arg260. RT-PCR analysis demonstrated that only one kind of mRNA coding for the Arg260-Cys mutation was expressed in the patient at a normal level. Another possible defective allele of the A subunit gene with a G-A polymorphism was not expressed (null allele). The substitution of Arg260 by Cys located on the interface of two A subunits would preclude the reciprocal ionic interaction (salt bridge) between Arg260 and Asp404. Molecular modelling and, for the first time, molecular mechanics calculated that Cys260 changed the local conformation of the A subunit and reduced the electrostatic interaction between two monomers, suggesting destabilization of the molecule's dimer.

Tissue specific and androgen-regulated expression of human prostate-specific transglutaminase

Transglutaminases (TGases) are calcium-dependent enzymes catalysing the post-translational cross-linking of proteins. In the prostate at least two TGases are present, the ubiquitously expressed tissue-type TGase (TGC), and a prostate-restricted TGase (TGP). This paper deals with the molecular cloning and characterization of the cDNA encoding the human prostate TGase (hTGP). For this purpose we have screened a human prostate cDNA library with a probe from the active-site region of TGC. The largest isolated cDNA contained an open reading frame encoding a protein of 684 amino acids with a predicted molecular mass of 77 kDa as confirmed by in vitro transcription-translation and subsequent SDS/PAGE. The hTGP gene was tissue-specifically expressed in the prostate, yielding an mRNA of approx. 3.5 kb. Furthermore, a 3-fold androgen-induced upregulation of hTGP mRNA expression has been demonstrated in the recently developed human prostate cancer cell line, PC346C. Other well established human prostate cancer cell lines, LNCaP and PC-3, showed no detectable hTGP mRNA expression on a Northern bolt. The gene coding for prostate TGase was assigned to chromosome 3.

Novel aspects of blood coagulation factor XIII. I. Structure, distribution, activation, and function

Blood coagulation factor XIII (FXIII) is a protransglutaminase that becomes activated by the concerted action of thrombin and Ca2+ in the final stage of the clotting cascade. In addition to plasma, FXIII also occurs in platelets, monocytes, and monocyte-derived macrophages. While the plasma factor is a heterotetramer consisting of paired A and B subunits (A2B2), its cellular counterpart lacks the B subunits and is a homodimer of potentially active A subunits (A2). The gene coding for the A and B subunits has been localized to chromosomes 6p24-25 and 1q31-32.1, respectively. The genomic as well as the primary protein structure of both subunits has been established, and most recently the three-dimensional structure of recombinant cellular FXIII has also been revealed. Monocytes/macrophages synthesize their own FXIII, and very likely FXIII in platelets is synthesized by the megakaryocytes. Cells of bone marrow origin seem to be the primary site for the synthesis of subunit A in plasma FXIII, but hepatocytes might also contribute. The B subunit of plasma FXIII is synthesized in the liver. Plasma FXIII circulates in association with its substrate precursor, fibrinogen. Fibrin(ogen) has an important regulatory role in the activation of plasma FXIII. The most important steps of the activation of plasma FXIII are the proteolytic removal of activation peptide by thrombin, the dissociation of subunits A and B, and the exposure of the originally buried active site on the free A subunits. The end result of this process is the formation of an active transglutaminase, which cross-links peptide chains through epsilon(gamma-glutamyl)lysyl isopeptide bonds. Cellular FXIII in platelets becomes activated through a nonproteolytic process. When intracytoplasmic Ca2+ is raised during platelet activation, the zymogen--in the absence of subunit B--assumes an active configuration. The protein substrates of activated FXIII include components of the clotting-fibrinolytic system, adhesive and contractile proteins. The main physiological function of plasma FXIII is to cross-link fibrin and protect it from the fibrinolytic plasmin. The latter effect is achieved mainly by covalently linking alpha 2 antiplasmin, the most potent physiological inhibitor of plasmin, to fibrin. Plasma FXIII seems to be involved in wound healing and tissue repair, and it is essential to maintaining pregnancy. Cellular FXIII, if exposed to the surface of the cells, might support or perhaps take over the hemostatic functions of plasma FXIII; however, its intracellular role has remained mostly unexplored.

Molecular basis of inherited factor XIII deficiency: identification of multiple mutations provides insights into protein function

Factor XIII (FXIII) is a zymogen essential for normal haemostasis. In inherited FXIII deficiency the majority of cases show absence of the FXIIIa subunit. Molecular analysis of PCR-amplified FXIIIa subunit exonic regions, and of RT-PCR amplified cDNA from six patients with FXIIIa subunit deficiency, from five unrelated families, has revealed 10 sequence changes: three mutations resulting in abnormal splicing of pre-mRNA, one nonsense mutation, one deletion/insertion change, three point mutations producing Val34Leu, Asn60Lys and Arg408Gln changes, and two silent mutations. In three families the patients are homozygous for a specific deficiency causing mutation, and patients from the remaining two families are compound heterozygotes. Understanding the molecular pathology of the disorder provides insights into the structure-function relationships of the various domains within the FXIII protein. From a clinical point of view, it enables direct diagnosis at the DNA level and may aid the development of FXIII analogues to promote wound healing.

Structure and organization of the human transglutaminase 3 gene: evolutionary relationship to the transglutaminase family

The human haploid genome contains a family of at least five different transglutaminases that are differentially expressed in time- and tissue-specific ways. Of these, transglutaminase 3 (TGase3) is unusual in that it is a pro-enzyme requiring activation by proteolysis. To date it is known to be expressed only in terminally differentiating epidermal and hair follicle keratinocytes. In this paper we show that it is encoded by a gene (TGM3) of 42.8 kbp containing 13 exons. In the course of isolation of genomic clones for the TGM3 gene, we also found clones encoding the widely expressed tissue or TGase2 enzyme, perhaps due to high degrees of sequence homology. The structure of the TGM2 gene has not yet been reported. Our incomplete data suggest its exon/intron organization is very similar to that of TGM3. Although the common intron splice points of all members of the transglutaminase gene family have been conserved, the TGM3 and TGM2 genes, and the gene for the subplasma membrane transglutaminase-like protein band 4.2, lack two introns found in the TGM1 and factor XIIIa genes, and the exact intron splice point of another intron is shifted with respect to that of the TGM1 and factor XIIIa genes. Based on sequence homologies and gene structures, the data support a phylogenic tree in which the TGM2 and TGM3 genes belong on a branch distinct from other transglutaminases.

Chromosomal localization of the human urokinase plasminogen activator receptor and plasminogen activator inhibitor type-2 genes: implications in colorectal cancer

Activation of the proenzyme of urokinase (uPA) on the surface of cancer cells has been implicated in the initiation of focal proteolytic mechanisms that permit invasion and metastasis by colon cancers. The activity of uPA on the cell surface appears to be a function of the number of uPA-specific receptors (uPAR) and the extent of inhibition of uPA by plasminogen activator inhibitors (PAI). The mapping of the genes coding for uPAR, and for PAI-2, was performed to determine whether their chromosomal localization suggested their involvement in the genetic alterations associated with cancer cell DNA. This study confirms the localization of the human urokinase plasminogen activator receptor gene to chromosome 19q and, using in situ hybridization, provides a precise localization to chromosome 19q13.2. In addition, our results confirm the previous allocation of the human plasminogen activator inhibitor-2 gene to a location 18q21.3-->18q22.1, a location that corresponds to the commonest (> 70%) somatic deletions found in colorectal carcinomas. The mapping of the uPAR and PAI-2 genes enables the elucidation of their possible involvement in the genetic alterations that determine the invasive and metastatic phenotypes in colorectal cancer.

Identification of a human specific Alu insertion in the factor XIIIB gene

The factor XIIIB gene was examined to determine the nature of a previously described 300 bp restriction fragment length polymorphism (RFLP) seen in the human population. Polymerase chain reaction analysis of different regions within the factor XIIIB gene was carried out to define a high resolution map of the region encompassing the polymorphism, followed by DNA sequence analysis. An Alu insertion was found to be the source of this variation. This Alu repeat is a member of the human specific-1 (HS-1) subfamily, although one of the five diagnostic nucleotides is a cattarhine specific (CS) subfamily mutation, suggesting that it may represent an intermediate form in the evolution between these two subfamilies. Subsequently, we developed a PCR-based assay to detect the polymorphism, rendering it a more useful marker for genetic linkage studies and genome mapping. This insertion is also a valuable polymorphism for human population studies, as demonstrated by the large variations in allele frequencies seen in three population groups.

Factor XIII: inherited and acquired deficiency

Factor XIII (XIII), an enzyme found in plasma (present as a pro-enzyme), platelets and monocytes, is essential for normal haemostasis. It may also have a role to play in the processes of wound healing and tissue repair. Inherited XIII deficiency results in a life-long, severe bleeding diathesis which, if untreated, carries a very high risk of death in early life from intracranial bleeding. XIII is a zymogen requiring thrombin and calcium for activation. In plasma, XIII has two subunits: the 'a' subunit, which is the active enzyme, and the 'b' subunit which is a carrier protein. Activated XIII modifies the structure of clot by covalently crosslinking fibrin through an epsilon (gamma-glutamyl)lysine link. It also crosslinks other proteins, including fibronectin and alpha-2-plasmin inhibitor (alpha-2PI), into the clot through the same link. Clot modified by XIII is physically stronger, relatively more resistant to fibrinolysis and may be a more suitable medium for the ingrowth of fibroblasts. Inheritance of factor XIII is autosomal recessive. The majority of patients with the inherited defect show no XIII activity and absence of 'a' subunit protein in plasma, platelets and monocytes. At the molecular level, the defect is not a major gene rearrangement or deletion, but most likely a single point mutation which may be different in each family. Because of the severity of the bleeding diathesis, prophylaxis is desirable and has been shown to be very effective as the in vivo half-life of plasma XIII is long, and low plasma levels are sufficient for haemostasis. Acquired inhibitors have been reported in only two cases with inherited XIII deficiency. Acquired XIII deficiency has been described in a variety of diseases and bleeding has been controlled by therapy with large doses of XIII in such conditions as Henoch-Schönlein purpura, various forms of colitis, erosive gastritis and some forms of leukaemia. Large dose XIII therapy has also been used in an endeavour to promote wound healing after surgery and bone union in non-healing fractures. The use of XIII in these conditions remains controversial. Very rarely a bleeding diathesis results from the development of a specific inhibitor to XIII arising de novo, often as a complication in the course of a disease or in association with long-term drug therapy. The bleeding diathesis in these patients is difficult to treat.

Mapping of RXRB to human chromosome 6p21.3

Retinoid X Receptor beta (RXRB) is a member of the retinoid X receptor (RXR) family of nuclear receptors which are involved in mediating the effects of retinoic acid (RA). We have confirmed the localization of RXRB to chromosome 6 and we have mapped the gene to chromosome 6p21.3-p21.1 by PCR amplification of 5' untranslated sequence in panels of rodent-human somatic cell hybrids and to 6p21.3 by fluorescent in situ hybridization.

Deficiency of coagulation factor XIII A subunit caused by the dinucleotide deletion at the 5' end of exon III

A congenital deficiency of the coagulation Factor XIII A subunit (F XIII A) is a rare autosomal recessive disorder that is characterized by a life-long bleeding tendency complicated by a difficulty in healing. Thus far, no molecular genetic analysis of this disorder has been reported. In this study, we demonstrate the molecular abnormalities in a family with this disorder. We performed Northern blot analysis of peripheral blood monocytes obtained from the propositus and found a 4-kb single band of F XIII A mRNA whose size was identical with that of normal subjects. Exons II-XV, which encode all the amino acids, were individually amplified by a polymerase chain reaction (PCR). All PCR products from the propositus had lengths indistinguishable from those of the wild type on agarose gel, suggesting that this defect results from either a point mutation or a short deletion/insertion. The sequencing of F XIII A cDNA from the propositus revealed a deletion of the dinucleotide AG within the AGAG repeat at the position of 210 to 213. Concerning the genomic sequence, a deletion of dinucleotide AG was also demonstrated in the intron B-exon III boundary. This deletion appeared to cause a frameshift mutation making a new stop codon shortly thereafter, and leading to a deficiency of plasma F XIII A. The heterozygosity of the F XIII A deficiency in the patient's offspring was documented by the nucleotide sequences of their exon III.

Population genetics of coagulation factor XIIIB in three ethnic groups of Singapore

The distribution of plasma coagulation factor XXIIB polymorphism was determined by PAG isoelectric focusing and immunoblotting in a group of 670 subjects comprising 375 Chinese, 110 Malays and 185 Indians. The frequencies of FXIIIB*1, FXIIIB*2, and FXIIIB*3 were found to be 0.27, 0.03 and 0.70 in the Chinese; 0.33, 0.05 and 0.64 in the Malays and 0.58, 0.08 and 0.33 in the Indians. The phenotypic distribution of FXIIIB alleles was at Hardy-Weinberg equilibrium in all three populations. A two-dimensional principal-components analysis on the basis of three common alleles at the FXIIIB locus among 19 populations, so far studied, clearly differentiates the Negroid, Mongoloid and Caucasoid populations into three major groups with the exception of Amerindians (Minnesota) and US Blacks showing some Caucasoid influence.

Sixty-five radiation hybrids for the short arm of human chromosome 6: their value as a mapping panel and as a source for rapid isolation of new probes using repeat element-mediated PCR

We have used an irradiation and fusion procedure to generate somatic cell hybrids that retain fragments of the short arm of human chromosome 6 (6p). To identify hybrids retaining human material, we performed repeat element-mediated PCR on crude lysates of cells from individual clones. Sixty-five hybrids were shown to contain human material and fifty of those contained one or more 6p-specific probes. Detailed characterization of these hybrids identified a subset that divides 6p into ten mapping intervals. Using repeat element-mediated PCR, we were able to isolate and map 61 new DNA fragments from specific regions of 6p. Fifteen of these fragments were used to screen for restriction fragment length polymorphisms (RFLPs), and nine identified RFLPs with one or more enzymes. The radiation hybrids described in this study provide a valuable resource for high-resolution mapping of 6p and for the rapid isolation of region-specific markers.