FXII Gene Research Articles

Analysis of an Inherited FXII Deficiency Pedigree Associated with Double Heterozygous Mutations in the F12 Gene.

This article is intended to identify the potential mutations of the FXII gene (F12) in an inherited FXII deficiency pedigree and illuminate the pathogenesis of the disease. The coagulation FXII activity (FXII:C) and FXII antigen (FXII:Ag) were inspected by one-stage clotting assay and enzyme-linked immunosorbent assay(ELISA), respectively. Polymerase chain reaction amplification (PCR) was performed and the F12 gene was sequenced directly. A molecular model of FXIIprotein was established for further analysis. ClustalX-2.1-win and online bioinformatic software were used to estimate the conservatism and possible impact of the protein change. The proband presented prolonged APTT(180s) and extreme low FXII:C and FXII:Ag (both < 1%, reference range:72-113%). A compound heterozygous were found by the direct sequencing of the F12 gene. One was a deletion mutation c.1792_1796delGTCTA, which is a novel mutation; the other was an insertion mutation, c.1092_1093insC. Bioinformatic and modeling analyses indicated that the the two frameshift mutations may be deleterious and possibly alter the structure and the function of the protein. The mutations c.1792_1796delGTCTA and c.1092_1093insC could be the main causes of reducing FXII in this pedigree, and c.1792_1796delGTCTA mutation was the first report in the world.

Investigation on abnormal gene loci of a Chinese pedigree with hereditary combined deficiency of blood coagulation factor XI, XII, and protein S

ObjectiveIn order to clarify the interaction mechanism, the phenotype and abnormal gene loci of FXI, FXII, and PS were investigated in this study. MethodsChinese pedigree with hereditary combined deficiency of coagulation factor (F) XI, FXII, and PS was enrolled in our study. Activated partial thromboplastin time (APTT), partial thromboplastin time (PT), FXI:C, FXII:C, and protein S (PS):C were determined using the one-stage coagulation method. FXI:antigen (Ag), FXII:Ag, and PS:Ag were detected using enzyme-linked immunosorbent assay (ELISA). Exons and introns of the FXI, FXII, and PS genes were amplified by polymerase chain reaction (PCR), and gene sequencing results were analyzed using Chromas software. ResultsA deletion of two bases located in introns A-149 and-150 within the FXI gene of the proband, his father, wife, and both sons. A missense variant in exon 14 (GGT → AGT, Gly542Ser) within FXII of the proband, his parents, and both sons. Four variants in exon 4 within the PS gene of all members of the pedigree: GTT → GTG (Val46Val), CGC → CTC (Arg49Leu), CGT → CAT (Arg60His), and CAG → TAG (Gln61stop). ConclusionsNone of the pedigree members showed a tendency for bleeding or thrombosis. Therefore, we speculated that the lack of coagulation factors counteracted the lack of PS, restoring the balance between the coagulation and anticoagulation systems. Another possible explanation is that these defects individually have only partial penetrance.

Influence of polymorphism of loci associated with reproductive qualities of large horned cattle on immunobiological parameters of carriers

In the structure of losses in the livestock industry, pathologies of the reproductive organs of cattle occupy a leading place, creating serious problems for motivating business owners to develop animal husbandry. A decrease in the rate of reproduction in animal husbandry is facilitated by the wide spread of symptomatic infertility of cows, one of the main reasons for which is gynecological diseases: metritis, mastitis and ovarian pathologies. As a result of the studies, the authors obtained reliable data indicating that in case of reproduction problems in cows, the platelet level decreases by 32%. The phagocytic capacity in animals with reproductive problems after 120 minutes of incubation is lower than in healthy animals, as is the activity of the microbicidal system of neutrophilic granulocytes, which indicates a lower degree of lysis of microbial cells. The authors studied the effect of the presence of a lethal mutation in the FXI gene on the immunobiological parameters of the Holstein cattle, which are problematic in terms of reproduction, carriers of the major histocompatibility complex gene BoLADRB3 and lethal mutation. In the course of the work, laboratory and clinical studies were carried out on 100 daughters of the bull Athlet 307 (JSC Krasnodarskoe for artificial insemination), a carrier of a lethal mutation in the FXI gene. The authors established the degree of influence of polymorphism of loci associated with the reproductive qualities of the large horned cattle on the immunobiological indices of their carriers in comparison with animals that do not have these loci. The given data are interesting, they should be taken into account when carrying out a survey of the livestock of farms unfavorable for the reproduction of cattle and the development of recreational measures.

Advances in the Pathogenesis of Hereditary Angioedema

Hereditary angioedema(HAE)is a rare,hereditary disease characterized by recurrent subcutaneous and submucosal edema.Known genes associated with the pathogenesis of HAE include C1 esterase inhibitor gene,FⅫ gene,plasminogen gene,and angiopoietin 1 gene.Based on the known gene mutations,this review analyzes the effects of these mutations on the functions of protein products to figure out the possible pathogenic mechanism,so as to provide references for further investigations on the pathogenesis of HAE and seeking new prevention and treatment approaches.

"Nuts and Bolts" of Laboratory Evaluation of Angioedema.

Angioedema, as a distinct disease entity, often becomes a clinical challenge for physicians, because it may cause a life-threatening condition, whereas prompt and accurate laboratory diagnostics may not be available. Although the bedside diagnosis needs to be established based on clinical symptoms and signs, family history, and the therapeutic response, later, laboratory tests are available. Currently, only for five out of the nine different types of angioedema can be diagnosed by laboratory testing, and these occur only in a minority of the patient population. Hereditary angioedema with C1-inhibitor (C1-INH) deficiency type I can be diagnosed by the low C1-INH function and concentration, whereas in type II, C1-INH function is low, but its concentration is normal or even elevated. C1q concentration is normal in both forms. Acquired angioedema with C1-INH deficiency type I is characterized by the low C1-INH function and concentration; however, C1q concentration is also low, and autoantibodies against C1-INH cannot be detected. Complement profile of acquired angioedema with C1-INH deficiency type II is similar to that of type I, but in this form, autoantibodies against C1-INH are present. Hereditary angioedema due to a mutation of the coagulation factor XII can be diagnosed exclusively by mutation analysis of FXII gene. Diagnostic metrics are not available for idiopathic histaminergic acquired angioedema, idiopathic non-histaminergic acquired angioedema, acquired angioedema related to angiotensin-converting enzyme inhibitor, and hereditary angioedema of unknown origin; these angioedemas can be diagnosed by medical and family history, clinical symptoms, and therapeutic response and by excluding the forms previously described. Several potential biomarkers of angioedema are used to date only in research. In the future, they could be utilized into the clinical practice to improve the differential diagnosis, therapy, as well as the prognosis of angioedema.

Coagulation factor XII genetic variation, ex vivo thrombin generation, and stroke risk in the elderly: results from the Cardiovascular Health Study

The relationships of thrombin generation (TG) with cardiovascular disease risk are underevaluated in population-based cohorts. To evaluate the relationships of TG influenced by the contact and tissue factor coagulation pathways exvivo with common single-nucleotide polymorphisms (SNPs) and incident cardiovascular disease and stroke. We measured peak TG (pTG) in baseline plasma samples of Cardiovascular Health Study participants (n=5411), both with and without inhibitory anti-factorXIa antibody (pTG/FXIa(-) ). We evaluated their associations with ~50000 SNPs by using the IBCv2 genotyping array, and with incident cardiovascular disease and stroke events over a median follow-up of 13.2years. The minor allele for an SNP in the FXII gene (F12), rs1801020, was associated with lower pTG in European-Americans (β=-34.2±3.5nm; P=3.3×10(-22) ; minor allele frequency [MAF]=0.23) and African-Americans (β=-31.1±7.9nm; P=9.0× 10(-5) ; MAF=0.42). Lower FXIa-independent pTG (pTG/FXIa(-) ) was associated with the F12 rs1801020 minor allele, and higher pTG/FXIa(-) was associated with the ABO SNP rs657152 minor allele (β=16.3nm; P=4.3×10(-9) ; MAF=0.37). The risk factor-adjusted ischemic stroke hazard ratios were 1.09 (95% confidence interval CI1.01-1.17; P=0.03) for pTG, 1.06 (95% CI0.98-1.15; P=0.17) for pTG/FXIa(-) , and 1.11 (95% CI1.02-1.21; P=0.02) for FXIa-dependent pTG (pTG/FXIa(+) ), per one standard deviation increment (n=834 ischemic strokes). In a multicohort candidate gene analysis, rs1801020 was not associated with incident ischemic stroke (β=-0.02; standard error=0.08; P=0.81). These results support the importance of contact activation pathway-dependent TG as a risk factor for ischemic stroke, and indicate the importance of F12 SNPs for TG exvivo and invivo.

Detection of Factor XI Deficiency (FXID) and Complex Vertebral Malformation (CVM) in Bali Cattle

Factor XI Deficiency (FXID) is caused by imperfect insertion of poly adenine which is resulted in introduction of premature stop codon in FXI gene. Substitution of guanine into thymine in SLC35A3 gene caused Complex Vertebral Malformation (CVM). The research was aimed to detect the presence or absence of a genetic defect mainly CVM using SLC35A3 gene and FXID using FXI gene in Indonesian Bali cattle. The presence of this genetic defect may have a significant economic impact on the breeding program. The research of genetic defect was done mostly in dairy cattle, but there was no report for screening of genetic defect in Bali cattle. In this study, 303 fresh blood samples and 22 semen samples which were collected from Indonesian Bali cattle breeding center (BPTU HMT Denpasar, BPT HMT Serading West Nusa Tenggara and district Barru South Sulawesi) and artificial insemination centre (BBIB Singosari and BIBD Baturiti) were used for screening of FXID and CVM. The amplicons of FXI gene were obtained by using PCR and that for SLC35A3 gene were obtained by using PCR-RFLP method with PstI restriction enzyme. These PCR products were analyzed by using 2% agarose gels electrophoresis. All genotypes were confirmed by DNA sequencing to determine an allele mutant. The allele mutant was not found in all of the samples. The result of this study showed that CVM and FXID were not detected in Bali cattle from Indonesian Bali cattle breeding and artificial insemination centres. Key words: Bali cattle, genetic defect, SLC35S3 gene, factor XI gene

Role of matrix metalloproteinase-2 and matrix metalloproteinase-9 in patients with recurrent miscarriage

predicted the subsequent pregnancy outcome in the cohort study. On the other hand, and intermediate FXII activity level of 85-101%was predictive of subsequentmiscarriage. Conclusions:TheC/T genotype, but not lowFXII activity was confirmed to be a risk factor for PRL. However, neither the C/T genotype nor low FXII activity had any predictive effect on the for subsequent pregnancy outcome. The CT genotype of the FXII gene was found to be a risk factor for PRL.

The serum level of vitamin D of endometriosis patients

predicted the subsequent pregnancy outcome in the cohort study. On the other hand, and intermediate FXII activity level of 85-101%was predictive of subsequentmiscarriage. Conclusions:TheC/T genotype, but not lowFXII activity was confirmed to be a risk factor for PRL. However, neither the C/T genotype nor low FXII activity had any predictive effect on the for subsequent pregnancy outcome. The CT genotype of the FXII gene was found to be a risk factor for PRL.

Gene analysis in four inherited coagulation FⅫ deficiency pedigree

To identify the genotype and pathogenesis in four Chinese pedigrees with Factor Ⅻ deficiency. Activated partial thromboplastin time (APTT), FⅫ procoagulant activity (FⅫ∶C), FⅫ antigen（FⅫ∶Ag）and other coagulant parameters were detected. The FⅫ deficiency Pedigree members,all exons,boundary introns including the splice junctions of the FⅫ gene were amplified with Polymerase chain reaction (PCR). Expression plasmids were constructed by mutagenesis based on the wild-type and transfected into COS7 cells. FⅫ∶C and FⅫ∶Ag of the expression levels were tested in the supernatant and cell lysate. The four probands presented prolonged APTT with all the values of FⅫ∶C and FⅫ∶Ag were low to 2% and 1%, respectively. There were common 46C/T polymorphism in the promoter regions of FⅫ gene in four pedigrees. Proband A was heterozygous for two mutations, g.5741-5742delCA (His101Gln) and g.7142insertC (Lys346Gln). Proband B was a heterozygous deletion mutation g.6800-6808del9bp. The results of the transfection revealed that FⅫ∶Ag in cell lysates and conditioned media protein FⅫ6800-6808del9bp were 85.6% and 51.9%. The FⅫ∶C in the conditioned media was 56.4%. Proband C was a heterozygous mutation g.8699G>A(Gly542Ser). Proband D was a homozygous mutation 8699G>A, whose parents with consanguineous marriage. Four mutations, g.5741-5742delCA, g.7142insertC, g.6800-6808del9bp and g.8699G>A with 46C/T polymorphism in the promoter regions of FⅫ gene, were identified in the four Factor Ⅻ deficiency pedigrees. The two mutations g.5741-5742delCA and g.6800-6808del9bp were first found in China. FⅫ 6800-6808del9bp expressed in vitro suggested that almost normal proteinum synthesis but defect proteinum secretion.

Factor XI mutation in normally fertile and repeat breeding Holstein cows in the Middle Anatolian region of Turkey: a financial approach

The aim of this study was to compare the prevalence of factor XI deficiency (FXID) carriers and potential financial losses depending on ‘extended calving interval’ and ‘extra service’ in normally fertile and repeat breeder cows in Turkey. For this purpose, a total of 161 Holstein cows were genotyped for the FXI gene mutation originating from various herds located in the Middle Anatolian region of Turkey. In the study, animals were divided into two groups – normally fertile (n = 118) and repeat breeding (n = 43) cows. In each group, one FXID carrier animal was identified and the prevalence of the FXID carrier was found to be 0.85 and 2.33% in normally fertile and repeat breeder cows, respectively. In a financial analysis, it was determined that extended calving interval in a normally fertile cow caused $246 losses and $546 losses in a repeat breeder cow. Additionally, financial losses due to extra service per conception were calculated as $12 and $36 per cow in normally fertile and repeat breeder cows, respectively. In normally fertile and repeat breeder cows, the sum of losses due to extended calving interval and extra service was calculated as $258 (246 + 12) and $582 (546 + 36). This study found that a repeat breeder cow causes an extra $324 ($582 – $258) financial loss compared with a normally fertile cow. Consequently, unlike other genetic disorders like BLAD and DUMPS, which do not decrease the performance of carrier animals, the mutant FXI allele could lead to repeat breeder syndrome in FXID carrier cows and cause important financial losses in dairy farms.

Association of C46T genetic polymorphism of coagulation factor XII with deep venous thrombosis: a cohort study on Egyptian patients

Deep vein thrombosis (DVT) is a common multi-factorial disease, with serious short- and long-term complications, and a potential fatal outcome. Many genes are involved in determining the interindividual variation in traits that define the onset and progression of disease, as well as the response to treatment. Several association studies have designed the relationship between factor XII C46T polymorphism and the risk of arterial and venous thrombosis. Some studies reported that FXII gene polymorphism is not associated with venous thrombosis, whereas other studies found an increased risk of venous thrombosis in carriers of a FXII-T variant. We constructed an age–gender–ethnic–matched case–control study including 52 DVT patients and 100 healthy volunteers. C46T polymorphism of the coagulation factor XII was carried out using allelic discrimination assay by real-time polymerase chain reaction for patients and controls, while plasma factor XII activity was detected by one-step clotting assay. FXII C46T genotyping in DVT patients revealed that 34.6% were heterozygous harboring the FXII-CT heterotype and 3.85% were homozygous; FXII-TT homotype, with no statistically significant difference in the distribution of the mutant genotypes between DVT patients and the control group. FXII activity was significantly reduced in DVT patients harboring the mutant genotypes. In the present study, FXII C46T gene polymorphism was not associated with increased risk of deep venous thrombosis.

Candidate Gene Polymorphisms and the Risk for Pregnancy Related Venous Thrombosis

AbstractAbstract 4203 Background:Venous thrombosis (VT) is the leading cause of maternal death in the western world. Genetic causes of pregnancy related VT are insufficiently understood.Objectives: To investigate if recently discovered associations between single nucleotide polymorphisms (SNPs) and thrombotic disease influenced the risk for pregnancy related VT. To investigate candidate genes for new associations between SNPs and pregnancy related VT. Methods:A hospital based case control study. Cases were women with objectively verified VT during pregnancy or puerperium, controls were women giving birth without having VT. We selected 49 candidate genes involved in coagulation (35 genes), inflammation (4 genes), and hormonal metabolism (10 genes). In these genes, 463 tag-SNPs were selected from the CEU population in Hapmap and analyzed in 313 cases and 353 controls. Odds ratios for VT were calculated with the most common genotype as the reference genotype for each SNP. P-values were adjusted for multiple testing to false discovery rates. Results:Of the SNPs previously shown by others to be associated to thrombotic disease, rs2289252 in the FXI gene (F11), rs3917643 in the tissue factor gene (F3), rs1613662 in the glycoprotein VI gene, rs2001490 in NAT8B, rs4524 in the FV gene (F5), and rs3087505 in the prekallikrein gene were associated to pregnancy related VT. After analyzing all 463 tag-SNPs, 13 SNPs were associated to total pregnancy related VT with a false discovery rate ≤ 0.20. These SNPs belonged to F5, SELP (coding for P-selectin), F3, F8 (coding for factor VIII), and F11. When we studied antenatal and postnatal VT separately, 17 SNPs were associated with antenatal VT, while only 1 SNP was associated with postnatal VT. Thirteen SNPs in F5, SELP, or the gene for E-selectin were associated with thrombosis. After excluding carriers of factor V Leiden, 4 of these SNPs remained associated. Two SNPs in the gene for epidermal growth factor receptor (EGFR) were associated to antenatal thrombosis. Conclusion:Genetic variation seems more important for antenatal than for postnatal VT. We confirmed the importance of some SNPs for the risk for pregnancy related VT, in particular rs2289252 in F11. The EGFR-gene appears to be a new genetic locus associated with pregnancy related VT.Table 1SNPs associated with total pregnancy related VT, antenatal VT, or postnatal VT with false discovery rate ≤ 0.20.No (%) allelesGeneSNPControlsCasesOR (CI95)pTotal pregnancy related VTF5rs6427202274 (39)311 (50)1.6 (1.3–2.0)<0.001SELPrs2205895285 (41)191 (31)0.6 (0.5–0.8)<0.001SELPrs3917744202 (29)236 (38)1.5 (1.2–2.0)<0.001SELPrs2076074177 (25)112 (18)0.6 (0.5–0.8)0.001SELPrs2142760346 (49)362 (58)1.5 (1.2–1.8)0.001SELPrs2244529196 (28)227 (36)0.7 (0.5–0.9)0.001F5rs9332640247 (35)332 (53)1.5 (1.2–1.8)<0.001F11rs22892521–3278 (39)281 (45)1.4 (1.1–1.7)0.003F3rs3917643454 (8)23 (4)0.5 (0.3–0.8)0.002SELPrs3917854231 (33)160 (26)0.7 (0.5–0.9)0.003F5rs6427199291 (41)201 (32)0.7 (0.6–0.9)0.002F5rs9332542237 (34)163 (26)0.7 (0.5–0.9)0.002F8rs1472977153 (22)98 (16)0.7 (0.5–0.9)0.003Antenatal VTSELPrs2244529253 (36)187 (60)0.6 (0.4–0.8)<0.001F5rs6427202137 (39)79 (1)1.7 (1.3–2.3)<0.001F8rs1472977153 (22)43 (14)0.6 (0.4–0.8)0.004NAT8Brs20014902240 (34)136 (44)1.5 (1.1–2.0)0.003SELPrs2205895285 (41)95 (31)0.6 (0.5–0.9)0.002SELErs391741077 (11)56 (18)1.8 (1.2–2.6)0.002SELPrs3917744202 (29)119 (38)1.6 (1.2–2.2)0.002F5rs45241181 (29)53 (38)0.6 (0.4–0.8)0.003EGFRrs4947491252 (36)144 (46)1.5 (1.2–2.0)0.002SELPrs6131139 (20)88 (28)1.6 (1.2–2.1)0.004F5rs6427199291 (41)97 (28)0.7 (0.5–0.9)0.003SELPrs2142760346 (49)181 (58)1.5 (1.1–2.0)0.005EGFRrs2330951170 (24)101 (33)1.5 (1.1–2.0)0.006NR1I2rs2461825228 (32)74 (24)0.6 (0.5–0.9)0.006F3rs3917643454 (8)9 (3)0.4 (0.2–0.7)0.005PROS1rs8178607201 (29)64 (21)0.6 (0.5–0.9)0.007GP6rs16136622130 (18)36 (12)0.6 (0.4–0.9)0.007Postnatal VTSELPrs2076074177 (25)48 (15)0.5 (0.4–0.7)<0.001 Disclosures:No relevant conflicts of interest to declare.

Combination of FXI Antisense Oligonucleotide and Plavix® Treatment Results in Enhanced Antithrombotic Activity without Increased Risk of Bleeding in Mouse Models of Thrombosis.

Abstract 4173Factor XI (FXI) is a serine protease produced in the liver that contributes to thrombin generation via the intrinsic coagulation pathway. Also, it is a key component of an amplification pathway that is thought to sustain thrombin production at a wound site to maintain fibrin clot integrity. Loss of function mutations in the human FXI gene results in FXI deficiency, a disorder which is associated with only mild bleeding. In addition, high levels of FXI are a risk factor for thrombosis. We have previously presented the antithrombotic efficacy and safety of antisense oligonucleotide (ASO) mediated FXI depletion in various animal models of thrombosis. We have demonstrated that in combination with Lovenox®, FXI ASO treatment increases antithrombotic activity but does not increase bleeding risk. The purpose of the current study was to evaluate the relative risk/benefit of ASO mediated Factor XI depletion in combination with the platelet antagonist Plavix®. The “risk” component was bleeding tendency as measured by blood volume loss following tail nick, and the “benefit” component was antithrombotic effect in arterial and venous mouse models of thrombosis. Our study investigated a 20 mg/kg dose of FXI ASO in combination with a dose response of Plavix® and indicates that antisense mediated FXI depletion provides enhanced antithrombotic protection when given in combination with Plavix®. The combination of FXI ASO and Plavix® did not result in increased bleeding tendency. In contrast, treatment with a small molecule inhibitor of factor Xa in combination with Plavix® significantly increased bleeding. The approach used in this study is being used to define the ability of FXI ASO to combine with standard of care agents for the treatment of thrombosis. Disclosures:Gao:Isis Pharmaceuticals, Inc.: Employment. Crosby:Isis Pharmaceuticals, Inc.: Employment. MacLeod:Isis Pharmaceuticals: Employment. Bhattacharjee:Isis Pharmaceuticals, Inc.: Employment. Lowenberg:Isis Pharmaceuticals, Inc.: Consultancy. Levi:Isis Pharmaceuticals, Inc.: Consultancy. Monia:Isis Pharmaceuticals, Inc.: Employment.

Structural analysis of eight novel and 112 previously reported missense mutations in the interactive FXI mutation database reveals new insight on FXI deficiency

Factor XI (FXI) functions in blood coagulation. FXI is composed of four apple (Ap) domains and a serine protease (SP) domain. Deficiency of FXI leads to an injury-related bleeding disorder, which is remarkable for the lack of correlation between bleeding symptoms and FXI coagulant activity (FXI:C). The number of mutations previously reported in our interactive web database (http://www.FactorXI.org) is now significantly increased to 183 through our new patient studies and from literature surveys. Eight novel missense mutations give a total of 120 throughout the FXI gene (F11). The most abundant defects in FXI are revealed to be those from low-protein plasma levels (Type I: CRM-) that originate from protein misfolding, rather than from functional defects (Type II: CRM+). A total of 70 Ap missense mutations were analysed using a consensus Ap domain structure generated from the FXI dimer crystal structure. This showed that all parts of the Ap domain were affected. The 47 SP missense mutations were also distributed throughout the SP domain structure. The periphery of the Ap beta-sheet structure is sensitive to structural perturbation caused by residue changes throughout the Ap domain, yet this beta-sheet is crucial for FXI dimer formation. Residues located at the Ap4:Ap4 interface in the dimer are much less directly involved. We conclude that the abundance of Type I defects in FXI results from the sensitivity of the Ap domain folding to residue changes within this, and discuss how structural knowledge of the mutations improves our understanding of FXI deficiencies.

Four novel FXI gene mutations in three factor XI- deficient patients

Hereditary factor XI deficiency is a mild bleeding disorder, which is highly prevalent among Ashkenazi Jews, but has been reported in all populations. In Ashkenazi Jews, two factor XI gene mutations Glu 117X (type II) and Phe283Leu (type III) are particularly common. In other ethnic groups, factor XI deficiency is a rare bleeding disorder and is related to a variety of mutations throughout the factor XI gene. Three cases of quantitative factor XI deficiency in relation with four novel missense mutations are reported: a compound heterozygosity for two novel mutations (Ala 181 Val and Ala 412 Thr) with a severe factor XI deficiency and two missense mutations (His 388 Pro and Trp 407 Cys) in heterozygous patients with partial factor XI deficiency.

Increased risk for oral cancer is associated with coagulation factor XIII but not with factor XII

In light of recently found contribution of factors associated with thrombosis and inflammation to carcinogenesis, we investigated the possible association of coagulation factors XII and XIII with increased risk for oral cancer. In DNA samples of patients with oral squamous cell carcinoma and healthy controls of comparable ethnicity, age and sex, we studied the C46T polymorphism in FXII gene which affects gene transcription and the V34L polymorphism in FXIII gene which affects enzyme activity resulting in alteration of the fibrin network structure. No significant differences were observed in genotype and mutant allele frequencies of the FXII C46T polymorphism between patients and healthy controls. On the contrary, the obtained data for FXIII V34L polymorphism revealed a significant frequency increase of the L allele, which results in thinner fibrin network, in the whole group of patients compared to controls (33.1 versus 22.2% respectively, Fischer value P=0.006). In addition, LL homozygotes had a 3-fold greater risk for developing oral cancer (OR 2.893, 95% CI 1.056-7.890), while in VL heterozygotes a 2-fold greater risk was observed (OR 1.868, 95% CI 1.126-3.101). Significantly increased frequency of L allele was also observed in sub-groups of patients without family history of thrombophilia or cancer, with and without tobacco abuse and with alcohol abuse (P<0.05). Interestingly, in comparison to controls only patients with early cancer stages I and II had significantly increased L alleles and not patients with advanced stages III and IV. These findings suggest that the presence of L allele is strongly associated with oral cancer generation but not with its progression and metastasis. In the presence of L allele, the fibrin network is composed of thinner fibers, is less porous and facilitates tumor stroma formation and therefore tumor cell proliferation. Nevertheless, this thinner and less porous fibrin network inhibits cell migration.

Adaptation or biased gene conversion? Extending the null hypothesis of molecular evolution

The analysis of evolutionary rates is a popular approach to characterizing the effect of natural selection at the molecular level. Sequences contributing to species adaptation are expected to evolve faster than nonfunctional sequences because favourable mutations have a higher fixation probability than neutral ones. Such an accelerated rate of evolution might be due to factors other than natural selection, in particular GC-biased gene conversion. This is true of neutral sequences, but also of constrained sequences, which can be illustrated using the mouse Fxy gene. Several criteria can discriminate between the natural selection and biased gene conversion models. These criteria suggest that the recently reported human accelerated regions are most likely the result of biased gene conversion. We argue that these regions, far from contributing to human adaptation, might represent the Achilles' heel of our genome.

Plasma levels of bradykinin are suppressed in factor XII-deficient mice

A genetically-transmissible factor (F) XII-inactivated allele has been produced in mice by targeted replacement of exons 3-8 of the FXII gene with the neomycin resistance gene. Interbreeding of these mice provided offspring homozygous for two inactivated FXII alleles (FXII(-/-)). Male and female FXII-deficient mice bred normally in all genotypic combinations of the heterozygous and homozygous states, and the offspring survived to adulthood, suggesting that a total FXII deficiency does not affect embryonic development and survival. Neither FXII transcripts nor FXII antigen was found in various tissues of adult FXII(-/-) mice. No obvious unchallenged coagulopathies were present in FXII(-/-) adult mice, despite greatly prolonged activated partial thromboplastin times in this mouse cohort. FXII(-/-) mice were then used to assess the in vivo importance of the plasma FXII/prekallikrein/kininogen pathway in provision of resting plasma bradykinin (BK) levels and in generation of plasma BK stimulated by contact with an artificial surface, using a new and greatly improved plasma BK assay developed during these studies. It was found that approximately 50% of resting BK, and all of the contact-stimulated plasma BK, was provided by this FXII-dependent pathway, without a requirement for FXI. These results provide clear evidence that surface-stimulated BK production, in mice, is dependent on the activation of FXII.

Phenotypic consequences of genetic variation at hemizygous alleles: Sotos syndrome is a contiguous gene syndrome incorporating coagulation factor twelve (FXII) deficiency

Purpose:We tested the hypothesis that Sotos syndrome (SoS) due to the common deletion is a contiguous gene syndrome incorporating plasma coagulation factor twelve (FXII) deficiency. The relationship between FXII activity and the genotype at a functional polymorphism of the FXII gene was investigated. MethodsA total of 21 patients including those with the common deletion, smaller deletions, and point mutations, and four control individuals were analyzed. We examined FXII activity in patients and controls, and analyzed their FXII 46C/T genotype using direct DNA sequencing. ResultsAmong 10 common deletion patients, seven patients had lower FXII activity with the 46T allele of the FXII gene, whereas three patients had normal FXII activity with the 46C allele. Two patients with smaller deletions, whose FXII gene is not deleted had low FXII activity, but one patient with a smaller deletion had normal FXII. Four point mutation patients and controls all had FXII activities within the normal range. ConclusionFXII activity in SoS patients with the common deletion is predominantly determined by the functional polymorphism of the remaining hemizygous FXII allele. Thus, Sotos syndrome is a contiguous gene syndrome incorporating coagulation factor twelve (FXII) deficiency.