A polymorphism in the 5' region of coagulation factor VII gene (F7) caused by an inserted decanucleotide

Extensive genetic screening of Iranian Factor FVII-deficient individuals unraveled several novel mutations and postulated founder effects in some cases

Background

As the most frequent congenital rare bleeding disorder that transmits in an autosomal recessive manner, factor VII (FVII) deficiency is a serious bleeding complication in populations with high rate of in-marriages. While diagnosis mainly relies on clinical and laboratory phenotypes, plasma FVII antigen and activity levels do not often correlate with symptoms' severity.

Objectives

Genetic profiling of the affected individuals potentially improves our biological understanding of this complicated rare disorder.

Methods

Conventional polymerase chain reaction-Sanger sequencing and whole-exome sequencing were applied for genetic profiling of F7 gene in 66 symptomatic FVII-deficient individuals from 62 independent pedigrees. Thirty-nine asymptomatic relatives of the patients were also studied.

Results

Thirty different F7 pathogenic variations were identified in the studied cases of which 11 have not been reported before. The novel mutations include 5 missenses (c.715G>A, c.794T>C, c.1090C>G, c.1222C>A, c.1265T>C), 3 splicing (c.316+1G>T, c.682-2A>G, c.572-16C>G), 2 nonsenses (c.790delC, c.1248G>A), and 1 frameshift (c.1346delA). A founder effect is proposed for c.790delC that was detected in 8 independent pedigrees who were all from similar geographical regions and ethnic backgrounds. Homozygous c.790delC reduces plasma FVII activity to <1% and causes spontaneous intracranial hemorrhage in early infancy.

Conclusion

From the 66 studied symptomatic FVII-deficient individuals, 58 were homozygous carriers of the identified variations. Identification of homozygotes clarifies the potential role of nucleotide variations in reducing FVII activity and their contributions to a certain phenotype. Some of those variations, such as c.1A>G, c.509G>A, c.634C>T, and c.1285G>A have only been previously reported as heterozygous.

Biochemical, molecular and clinical aspects of coagulation factor VII and its role in hemostasis and thrombosis

Activated factor VII (FVIIa), the first protease of clotting, expresses its physiological procoagulant potential only after complexing with tissue factor (TF) exposed to blood. Deep knowledge of the FVIIa-TF complex and F7 gene helps to understand the Janus-faced clinical findings associated to low or elevated FVII activity (FVIIc). Congenital FVII deficiency, the most frequent among the recessively inherited bleeding disorders, is caused by heterogeneous mutations in the F7 gene. Complete FVII deficiency causes perinatal lethality. A wide range of bleeding symptoms, from life-threatening intracranial hemorrhage to mild mucosal bleeding, is observed in patients with apparently modest differences in FVIIc levels. Though clinically relevant FVIIc threshold levels are still uncertain, effective management, including prophylaxis, has been devised, substantially improving the quality of life of patients. The exposure of TF in diseased arteries fostered investigation on the role of FVII in cardiovascular disease. FVIIc levels were found to be predictors of cardiovascular death and to be markedly associated to F7 gene variation. These genotype-phenotype relationships are among the most extensively investigated in humans. Genome-wide analyses extended association to numerous loci that, together with F7, explain >50% of FVII level plasma variance. However, the ability of F7 variation to predict thrombosis was not consistently evidenced in the numerous population studies. Main aims of this review are to highlight i) the biological and clinical information that distinguishes FVII deficiency from the other clotting disorders and ii) the impact exerted by genetically predicted FVII level variation on bleeding as well as on the thrombotic states.

Factor VII levels, R353Q and -323P0/10 Factor VII variants, and the risk of acute coronary syndrome among Arab-African Tunisians

The importance of the extrinsic haemostatic system, of which factor VII/VIIa (FVII/FVIIa) is a key constituent, in acute coronary syndrome (ACS) is well recognized. The contribution of FVII gene variants R353Q and -323P0/10, and altered FVII plasma levels to the risk of ACS was investigated in a North African Tunisian Arab cohort consisting of 308 ACS cases and 312 age-, gender- and ethnically-matched control subjects; FVII antigen levels were determined by ELISA. Regression analysis was used in assessing the association of FVII variants and changes in FVII levels to the overall risk of ACS. Significantly higher FVII antigen levels were seen in ACS patients (P < 0.001), and were associated with ACS and with ACS severity, and this association was confirmed by multivariate regression analysis, after adjusting for a number of confounders (BMI, smoking, systolic blood pressure, hypertension, diabetes, and glucose, cholesterol, and triglycerides levels). While the carriage of 353Q allele, was associated with significant reduction in FVII plasma levels, the distribution of the R353Q genotypes was comparable between cases and control subjects, thereby indicating that altered FVII levels, independent of R353 variant, were associated with increased risk of ACS. In contrast, the -323Ins variant, while not associated with altered FVII plasma levels, was associated with ACS, following adjustment for BMI, smoking, systolic blood pressure, hypertension, diabetes, and glucose, cholesterol, triglycerides and FVII levels. In summary, elevated FVII levels, and the -323P0/10 but not R353Q polymorphism, constitute risk factors for ACS.

A retrospective analysis of 157 surgical procedures performed without replacement therapy in 83 unrelated factor VII-deficient patients

BACKGROUND

 Inherited factor (F)VII deficiency is the commonest of the rare bleeding disorders, with a wide set of hemorrhagic features. Other than for the severe clinical forms (for which treatment guidelines are well defined), consistent recommendations regarding perioperative replacement management do not exist for mild and asymptomatic FVII-deficient patients.

OBJECTIVES

 The present study aimed to evaluate the influence of bleeding history, FVII procoagulant activity levels (FVII:C) and the type of surgical procedure on the management of inherited FVII-deficient patients before surgery.

PATIENTS

 One hundred and fifty-seven surgical procedures, performed without replacement therapy, in 83 unrelated FVII-deficient patients (median FVII:C=5%, range 0.6%-35%) were analyzed.

RESULTS

 The overall bleeding rate was 15.3%. We found a significant relationship between previous deep traumatic hematomas and bleeding at surgery, although relationships with previous common epistaxis, easy bruising and menorrhagia were not significant. The receiver-operating characteristic (ROC) curve analysis performed on the first 83 procedures allowed us to define a cut-off value of 7% with a sensitivity of 87% (negative predictive value: 94%). To enhance the sensitivity, and to take into account the potential variation resulting from non-standardized FVII:C measurements, we would suggest applying a threshold of 10%.

CONCLUSION

 We have proposed recommendations for the perioperative management of FVII-deficient patients based on FVII:C levels, a thorough bleeding history and the type of surgery involved. By applying these recommendations, minor procedures that risk only external or controlled hemorrhage can be performed in asymptomatic or mildly affected adults, even those with FVII:C levels below 10%.

MISS: a non-linear methodology based on mutual information for genetic association studies in both population and sib-pairs analysis

MOTIVATION

Finding association between genetic variants and phenotypes related to disease has become an important vehicle for the study of complex disorders. In this context, multi-loci genetic association might unravel additional information when compared with single loci search. The main goal of this work is to propose a non-linear methodology based on information theory for finding combinatorial association between multi-SNPs and a given phenotype.

RESULTS

The proposed methodology, called MISS (mutual information statistical significance), has been integrated jointly with a feature selection algorithm and has been tested on a synthetic dataset with a controlled phenotype and in the particular case of the F7 gene. The MISS methodology has been contrasted with a multiple linear regression (MLR) method used for genetic association in both, a population-based study and a sib-pairs analysis and with the maximum entropy conditional probability modelling (MECPM) method, which searches for predictive multi-locus interactions. Several sets of SNPs within the F7 gene region have been found to show a significant correlation with the FVII levels in blood. The proposed multi-site approach unveils combinations of SNPs that explain more significant information of the phenotype than their individual polymorphisms. MISS is able to find more correlations between SNPs and the phenotype than MLR and MECPM. Most of the marked SNPs appear in the literature as functional variants with real effect on the protein FVII levels in blood.

AVAILABILITY

The code is available at http://sisbio.recerca.upc.edu/R/MISS_0.2.tar.gz

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.

Vitamin K-induced modification of coagulation phenotype in VKORC1 homozygous deficiency

BACKGROUND

Combined vitamin K-dependent clotting factor (VKCF) deficiency type 2 (VKCFD2) is a rare bleeding disorder caused by mutated vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) gene.

METHODS AND RESULTS

An Italian patient with moderate to severe bleeding tendency was genotyped, and found to be homozygous for the unique VKORC1 mutation (Arg98Trp) so far detected in VKCFD2. The activity levels of VKCFs were differentially reduced, and inversely related to the previously estimated affinity of procoagulant factor propeptides for the gamma-carboxylase. The normal (factor IX) or reduced antigen levels (other VKCFs) produced a gradient in specific activities. Vitamin K supplementations resulted in reproducible, fast and sustained normalization of PT and APTT. At 24 h the activity/antigen ratios of VKCFs were close to normal, and activity levels were completely (factor VII and IX), virtually (prothrombin, factor X and protein C) or partially (protein S) restored. Thrombin generation assays showed a markedly shortened lag time. The time to peak observed at low tissue factor concentration, potentially mimicking the physiological trigger and able to highlight the effect of reduced protein S levels, was shorter than that in pooled normal plasma. At 72 h the thrombin generation times were normal, and the decrease in activity of procoagulant VKCFs was inversely related to their half-life in plasma. The improved coagulation phenotype permitted the uneventful clinical course after invasive diagnostic procedures.

CONCLUSIONS

Modification of coagulation phenotypes in VKCFD2 after vitamin K supplementation was clinically beneficial, and provided valuable patterns of factor specific biosynthesis, half-life and decay.

Postprandial factor VII metabolism: the effect of the R353Q and 10 bp polymorphisms

Elevated levels of coagulation factor VII activity (FVIIc) are associated with increased risk of CHD. FVIIc is strongly determined by two polymorphisms (R353Q and 0/10 base pairs (bp)) and plasma triacylglycerol (TAG) concentrations. The Q and 10 bp polymorphisms show strong linkage disequilibrium and have been associated with lower levels of fasting FVII, but there has been little investigation of the effect of these genotypes on the postprandial FVII metabolism. The present study demonstrated that fasting activated factor VII (FVIIa) and factor VII antigen (FVIIag) levels were significantly lower in the heterozygotes carrying the Q and 10 bp alleles (n12), than in the R/0 bp homozygotes (n12) (43·0 (SE 4·8)v. 23·9 (SE 6·5) mU/ml and 85·7 (SE 5·4)v. 71·6 (SE 7·5) % respectively). During postprandial lipaemia there was a significant increase in FVIIa in R/0 bp homozygotes but not in the heterozygotes carrying the Q and 10 bp alleles. The proportion of FVIIa (FVIIa : FVIIag) increased in the homozygotes but not in the heterozygotes (2·04 (SE 0·35)v. 1·20 (SE 0·26) respectively). Therefore possession of the relatively common Q and 10 bp alleles is not associated with postprandial activation of FVII, which may in turn have a protective effect against CHD.

The Effects of Three Factor VII Polymorphisms on Factor VII Coagulant Levels in Healthy Singaporean Chinese, Malay and Indian Newborns

Factor VII (FVII) is an independent risk factor for coronary artery disease. Three polymorphisms of the factor VII gene (F7) were studied in a group of healthy newborns comprising 561 Chinese, 398 Malays and 226 Asian Indians from Singapore. The allele frequencies of 3 polymorphisms (R353Q, Promoter 0/10bp Del/Ins and Intron 7) in the FVII gene were ascertained through genotyping by polymerase chain reaction and restriction digestion of amplified fragments. In Chinese the minor allele frequencies are Q: 0.04, Ins: 0.03, R7: 0.44; Malays, Q: 0.06, Ins: 0.10, R7: 0.41; and Indians, Q: 0.25, Ins: 0.23, R7: 0.43. Strong linkage disequilibrium (Delta > 0.7) is observed between the 0/10 bp and the R353Q sites in all ethnic groups. We conclude that: (i) the prevalence of the minor Q and Ins alleles of the R353Q and 0/10 bp polymorphisms are significantly higher in the Indian newborns than the Chinese and Malays; (ii) the Q allele is significantly associated (p = 0.01) with a lower plasma FVII coagulant level in the Indian and Malay neonates; and this polymorphism explains up to 3.8% of the variance in FVII coagulant levels; (iii) there is no significant difference in allele frequencies of the three polymorphisms between neonates with and without family histories of CAD.

Genetic architecture of the F7 gene in a Spanish population: implication for mapping complex diseases and for functional assays

Delineating the genetic variability of loci coding for complex diseases helps to understand the individual variation in disease susceptibility and drug response. We present the allelic architecture of the F7 gene. This gene is the major determinant of FVII plasma levels, and these plasma levels constitute an important intermediate risk factor for cardiovascular disease. As part of the Genetic Analysis of Idiopathic Thrombophila Project, we completely re-sequenced the F7 locus (promoter, exons, introns, and 3'-untranslated region) in 40 unrelated individuals. We found 49 polymorphisms with only two amino acid changes suggesting that regulatory non-coding and intronic variants are responsible for the FVII variability. These results are important for mapping susceptibility alleles of complex diseases, because differences in pair-wise linkage disequilibrium patterns between DNA variants and haplotype frequency distributions may help to detect disease-associated alleles. In addition, we present the results of an in silico search that established genomic comparisons among different species. In conclusion, our study of the F7 DNA sequence variations is an example of a strategy for analyzing the genetic architecture of a quantitative trait locus. Furthermore, it provides a model for future analyses of genetic factors that contribute to the susceptibility of complex diseases in humans.

Role of the 2 adenine (g.11293_11294insAA) insertion polymorphism in the 3' untranslated region of the factor VII (FVII) gene: molecular characterization of a patient with severe FVII deficiency

Polymorphic variants in the gene encoding factor VII (F7) affect the plasma levels of this coagulation protein and modify the clinical phenotype of FVII deficiency in some patients. In this study we report the in vitro functional analysis of a novel polymorphic variant located in the 3' untranslated region of F7: g.11293_11294insAA. To determine whether this variant regulates FVII expression, we initially compared an expression vector containing FVII cDNA with g.11293_11294insAA with the FVII wild-type (WT) construct. The kinetics of mRNA production showed that the insertion decreases the steady-state FVII mRNA levels. To assess whether the insertion influences the phenotype of FVII-deficient patients, we evaluated its effect on the expression of FVII in a patient with severe FVII deficiency (undetectable FVII activity and antigen) carrying two additional homozygous missense variations (p.Arg277Cys and p.Arg353Gln). The two substitutions alone reduced the expression of FVII activity and antigen in vitro, but with the insertion polymorphism in our expression vector the patient's phenotype of undetectable plasma FVII was recapitulated. The insertion polymorphism in the 3' untranslated region of F7 is another modifier of FVII expression that might explain the poor genotype-phenotype correlation in some FVII-deficient patients.

Coagulation and atherothrombotic disease

Atherothrombotic disease arises secondary to a complex gene-environment interaction. In the initial stages, the condition is clinically silent but with more advanced disease, an occlusive thrombus is formed resulting in the classical clinical manifestations. Both environmental factors and genetic variations in elements of the clotting cascade influence thrombosis risk by inducing quantitative and qualitative changes in the mature protein, which may affect the final structure of the clot and determine its resistance to lysis. Understanding the fine details of gene-environment interactions in relation to thrombus formation will help to shed more light on disease pathogenesis. Consequently, this will allow the development of more efficacious treatment strategies and will also help to identify subjects at risk, thereby enabling the introduction of early preventative measures.

Prolonged prothrombin time, Factor VII and activated FVII levels in chronic liver disease are partly dependent on Factor VII gene polymorphisms

BACKGROUND

Prothrombin time is a benchmark for functional assessment in cirrhosis and Factor VII levels (FVII), crucial in determining the prothrombin time, are genetically determined.

METHODS

We have evaluated the prothrombin time, a number of haemostatic variables synthesised by the liver (FII, FV, FVII and activated FVII, AT and fibrinogen) and two polymorphisms of the FVII gene (5'F7 and 353R/Q) in: (a) patients with liver cirrhosis (n=118), (b) patients with chronic hepatitis (n=102) and (c) controls (n=100).

RESULTS

By one-way analyses of variance, the prothrombin time and the mean levels of the FII, FV, FVIIc, FVIIa, and AT were statistically different between cirrhotics, chronic hepatitis patients and controls. The allele frequency of the FVII polymorphisms did not differ between the three groups. Those rare patients (4.6%) who were homozygous for the type 2 alleles had markedly reduced FVIIc and FVIIa levels. The analysis carried out taking into account Child class versus FVII genotype showed that the mean FVIIc levels were comparable for different genotypes within each Child's class, with the exception of the patients homozygous for the type 1 allele.

CONCLUSION

Our findings help to explain the not infrequent finding of a severely prolonged prothrombin time in patients who are otherwise in a good functional class.

Reduction in coagulation factor VII plasma levels by R353Q but not the -323P0/10 promoter polymorphism in healthy Tunisians

The association between the R353Q and -323P0/10 (10-bp insertion in the promoter region at position -323) factor VII mutations and plasma factor VII levels was investigated in a group of 214 healthy Tunisians. The frequency for the Q allele was 0.253 and that for the 10-bp allele was 0.206, and their distribution was variable, with a high prevalence of the 10-bp allele (0.306) seen in North Tunisia and a high prevalence of the Q allele (0.288) see in the Sahel region. No significant linkage disequilibrium was observed between the two mutations, and the most prevalent haplotype was -323P0/353R (0.589 +/- 0.054). Carriers of the R353Q (P < 0.001), but not -323P0/10 (P = 0.088), factor VII mutations had lower mean factor VII serum concentrations. This reduction in mean serum factor VII was more pronounced among homozygous (Q/Q) carriers and among males (49.9%) compared to females (32.7%). Adjusting for all other variables in the linear regression analysis (sex, age, region, smoking, and R353Q and -323P0/10 mutations), heterozygous carriers of the -323P0/10 and R353Q mutation had on average reductions of 10 units (P = 0.005) and 30 units (P < 0.001) in plasma factor VII, respectively, compared to noncarriers, while homozygote carriers of the R353Q (-43.3, P < 0.001), but not carriers of the -323P0/10 (-6.30, P = 0.356), had significantly lower levels of mean plasma factor VII. These data suggest that part of the previously described effects on FVIIc levels associated with the R/Q polymorphism may be explained by genetic variation in the promoter region of the FVII gene.

Population genetic and phylogenetic evidence for positive selection on regulatory mutations at the factor VII locus in humans

The abundance of cis-regulatory polymorphisms in humans suggests that many may have been important in human evolution, but evidence for their role is relatively rare. Four common polymorphisms in the 5' promoter region of factor VII (F7), a coagulation factor, have been shown to affect its transcription and protein abundance both in vitro and in vivo. Three of these polymorphisms have low-frequency alleles that decrease expression of F7 and may provide protection against myocardial infarction (heart attacks). The fourth polymorphism has a minor allele that increases the level of transcription. To look for evidence of natural selection on the cis-regulatory variants flanking F7, we genotyped three of the polymorphisms in six Old World populations for which we also have data from a group of putatively neutral SNPs. Our population genetic analysis shows evidence for selection within humans; surprisingly, the strongest evidence is due to a large increase in frequency of the high-expression variant in Singaporean Chinese. Further characterization of a Japanese population shows that at least part of the increase in frequency of the high-expression allele is found in other East Asian populations. In addition, to examine interspecific patterns of selection we sequenced the homologous 5' noncoding region in chimpanzees, bonobos, a gorilla, an orangutan, and a baboon. Analysis of these data reveals an excess of fixed differences within transcription factor binding sites along the human lineage. Our results thus further support the hypothesis that regulatory mutations have been important in human evolution.

The significance of published polymorphisms in 14 cases of mild factor VII deficiency

Factor VII (FVII) plays a critical role in the initiation of blood coagulation, and patients with dysfunctional or reduced levels of this protein are susceptible to mucosal bleeding. There is poor correlation between the clinical presentation and the phenotypic data; and in cases of a mild bleeding tendency, mild to moderate reductions in both FVII antigen and activity may be overlooked. The prevalence of FVII deficiency may therefore be underestimated. Polymorphic differences throughout the FVII gene are associated with variations in plasma FVII antigen and activity levels. This study highlights the significance of mild FVII deficiency, and examines the importance of seven previously published polymorphisms in such patients.

Coinheritance of Factor V (FV) Leiden enhances thrombin formation and is associated with a mild bleeding phenotype in patients homozygous for the FVII 9726+5G>A (FVII Lazio) mutation

We investigated the role of thrombophilic mutations as possible modifiers of the clinical phenotype in severe factor VII (FVII) deficiency. Among 7 patients homozygous for a cross-reacting material-negative (CRM-) FVII defect (9726+5G>A, FVII Lazio), the only asymptomatic individual carried FV Leiden. Differential modulation of FVII levels by intragenic polymorphisms was excluded by a FVII to factor X (FX) gene haplotype analysis. The coagulation efficiency in the FV Leiden carrier and a noncarrier was evaluated by measuring FXa, FVa, and thrombin generation after extrinsic activation of plasma in the absence and presence of activated protein C (APC). In both patients coagulation factor activation was much slower and resulted in significantly lower amounts of FXa and thrombin than in a normal control. However, more FXa and thrombin were formed in the plasma of the patient carrying FV Leiden than in the noncarrier, especially in the presence of APC. These results were confirmed in FV-FVII doubly deficient plasma reconstituted with purified normal FV or FV Leiden. The difference in thrombin generation between plasmas reconstituted with normal FV or FV Leiden gradually decreased at increasing FVII concentration. We conclude that coinheritance of FV Leiden increases thrombin formation and can improve the clinical phenotype in patients with severe FVII deficiency.

Pitfalls in molecular diagnosis in a family with severe factor VII (FVII) deficiency--misdiagnosis by direct sequence analysis using a PCR product

Molecular diagnostic tests are becoming a routine analysis in many laboratories. These modern analyses are widely used in clinical medicine, forensic, genetic and prenatal diagnosis and also in preimplantation genetic diagnosis. The accuracy of analysis is highly dependent on the success achieved in minimising genotyping errors. The pitfalls in molecular diagnostic tests can be due to a simple technique such as the polymerase chain reaction (PCR) used universally. This technique is routinely used for its apparent accuracy, but it is also a well-known source of errors. We report an error introduced during PCR reaction that leads to a wrong sequence result and consequently to a 'false' molecular result in a next prenatal diagnosis in a family with severe factor VII (FVII) deficiency. This error was verified using an unsuitable primer design in a rich repetitive sequence of the FVII gene that leads to a false annealing and then to a wrong molecular diagnosis. It is essential to link closely molecular data with clinical and phenotype analysis in order to avoid false-negative or false-positive results, which is of great importance to diagnosis and molecular prevention.

ARP1 interacts with the 5' flanking region of the coagulation factor VII gene

Factor (F)VII plays a critical role in initiation of coagulation. Several segments within the 5' flanking region of the FVII gene were previously demonstrated to recognize hepatic nuclear proteins, but few have been identified. To identify a regulatory protein binding the nuclear hormone response region (-237 to -200) of the FVII 5' flanking region and demonstrate that the interaction is functional. Electrophoretic mobility shift assays and mutation analysis showed that ARP1, an orphan nuclear hormone receptor, interacted with two regions of the FVII 5' flanking region, the hepatic nuclear factor 4 binding region (-77 to -47) and the nuclear hormone response region (-237 to -200). Transfection experiments demonstrated that reporter gene expression was decreased from vectors including the nuclear hormone response segment compared with that containing only the minimal promoter between positions -109 and +1, and that ARP1 also repressed expression through an interaction with the minimal promoter. These data indicate a role for ARP1 in transcriptional modulation of the FVII gene.

Two double heterozygous mutations in the F7 gene show different manifestations

We sequenced the factor VII gene (F7) in two unrelated Japanese patients with factor VII (FVII) deficiency. In the first (an asymptomatic 46-year-old man with FVII activity and antigen levels of 1.2% and 21% of normal respectively), novel E25K and H348Q mutations were identified in the doubly heterozygous state. In transiently transfected HEK293 cells, the level of FVII-E25K mutant activity in the culture media was significantly lower than that of FVII wild type, whereas the antigen levels of both proteins were similar. This suggests that the E25K mutation is associated with a dysfunctional FVII molecule. In the second patient (a 47-year-old woman with FVII activity and antigen levels of less than 1% and 6% respectively), an IVS4+1 mutation and a novel -96C to T transition were detected in the double heterozygous state. In electrophoretic mobility shift assays, the -96T mutation was shown to disrupt binding of Sp1.

Detection and quantification of insertion/deletion variations by allele-specific real-time PCR: application for genotyping and chimerism analysis

The DNA-based quantitative analysis of genetic chimerism is becoming increasingly more important for molecular biology in general and molecular medicine in particular. Useful genomic targets for these analyses are polymorphic sequences, but here the problem of a reliable quantification with high dynamic range is not yet satisfactorily solved. To this end we have combined the allele-specific amplification with a real-time PCR-based quantification for rapid allelotyping and chimerism analysis. The sequence variations are discriminated by the 3'-end of the allele-specific primer. Amplification is monitored by SYBR-Green I fluorescence. We demonstrate the efficiency of this method for two clinically relevant targets: (i) the 10 bp insertion/deletion polymorphism in the promoter of the factor VIIc (F-VIIc) gene and (ii) the 4G/5G single nucleotide polymorphism in the promoter of the plasminogen activator inhibitor-1 (PAI-1) gene. Both polymorphisms are associated with clinical risk factors. Allelotyping results were in complete agreement with those obtained by reference methods. Mixed chimeric DNA samples could be quantified reliably with a dynamic range of 1:3000 for an easy target (F-VIIc) and of 1:64 for a difficult target (PAI-1). Our protocol is particularly useful for rapid, reliable and inexpensive genotyping and quantitative chimerism analysis without requiring expensive fluorophor dye labelled probes.

Genetic contribution to factor VII levels in families of patients undergoing coronary arteriography

An elevated plasma level of factor VII is a risk factor for coronary artery disease. We investigated environmental, familial, and genetic influences on factor VII activity in 508 family members of 87 probands who underwent elective coronary arteriography. Maximum likelihood methods were used to fit several genetic and non-genetic models of inheritance to these data to determine whether an unobserved Mendelian major gene could explain the familial distribution of factor VII. Factor VII activities were adjusted for age, gender, body mass index, smoking, alcohol consumption, menopause status, and triglycerides prior to this segregation analysis (this model accounted for 33.5% of the total variation). Adjusted factor VII activities showed strong familial aggregation with an estimated parent-offspring correlation of 0.34, sibling correlation of 0.36 and a smaller spouse correlation of 0.16. Regressive models were used to test genetic and non-genetic models in these 87 families. Mendelian single-locus models with either two or three underlying genotypic distributions of factor VII activities were best supported by these data. Essentially, these Mendelian models suggest most individuals come from a low distribution (mean, 116%), with a few individuals homozygous for a high allele drawn from a distribution with a mean of 166%. Future linkage studies may be worthwhile to further clarify the mechanisms controlling factor VII activity.

Factor VII deficiency and the FVII mutation database

Factor VII (FVII) is a zymogen for a vitamin K-dependent serine protease essential for the initiation of blood coagulation. It is synthesized primarily in the liver and circulates in plasma at a concentration of approximately 0.5 microg/ml (10 nmol/L). The FVII gene (F7) is located on chromosome 13 (13q34), consists of 9 exons, and spans approximately 12kb. It encodes a mature protein of 406 amino acids, which has an N-terminal domain (Gla) post-translationally modified by gamma-carboxylation of glutamic acid residues, two domains with homology to epidermal growth factor (EGF1 and 2), and a C-terminal serine protease domain. The single chain zymogen is activated by proteolytic cleavage at Arg152-Ile153. There are 238 individuals described in the world literature with mutations in their F7 genes (FVII mutation database; europium.csc. mrc.ac.uk). Complete absence of FVII activity in plasma is usually incompatible with life, and individuals die shortly after birth due to severe hemorrhage. The majority of individuals with mutations in their F7 gene(s), however, are either asymptomatic or the clinical phenotype is unknown. In general, a severe bleeding phenotype is only observed in individuals homozygous for a mutation in their F7 genes with FVII activities (FVII:C) below 2% of normal, however, a considerable proportion of individuals with a mild-moderate bleeding phenotype have similar FVII:C by in vitro assay. The failure of in vitro tests to differentiate between these groups may be due to lack of sensitivity in the assays to the very low amounts of FVII:C, which are sufficient to initiate coagulation in vivo. A number of polymorphisms have been identified in the F7 gene and some have been shown to influence plasma FVII antigen levels.

Novel mutations in the Factor VII gene of Taiwanese Factor VII-deficient patients

The genetic defects of four Taiwanese patients with factor VII (FVII) deficiency were studied. FVII activity and antigen levels were < 1 u/dl and 125.7 u/dl (patient I), < 1 u/dl and < 1 u/dl (patient II), 3.4 u/dl and 5.9 u/dl (patient III), and 1.2 u/dl and 30.4 u/dl (patient IV) respectively. The 5' flanking region, and all exons and junctions were amplified using polymerase chain reaction and sequenced. Patient I was homozygous for a 10824C-->A transversion with Pro303-->Thr mutation in exon 8. In patient II, a heterozygous transversion, 9007+1G-->T at the IVS6, a heterozygous decanucleotide insertion polymorphism at -323 (both mutations present in his father) and a heterozygous deletion, del TC (26-27) in exon 1A (originating from his mother) were identified. Patient III had a homozygous 10961T-->G transversion with His348-->Gln mutation in exon 8. Patient IV had a heterozygous 10902T-->G transversion with Cys329-->Gly mutation in exon 8 (transmitted to her second son) and a heterozygous decanucleotide insertion polymorphism at -323 (transmitted to her third son). All but one of the FVII gene mutations detected in the four patients have not been previously reported. In conclusion, four novel mutations of the FVII gene in Taiwanese, including two missense mutations in exon 8, one point mutation at the exon 6 splice site and one deletion in exon 1A, were identified.

Reduced procedural risk for coronary catheter interventions in carriers of the coagulation factor VII-Gln353 gene

OBJECTIVES

We have focused on the role of coagulation factor VII (FVII) Arg353Gln polymorphism as a risk predictor of complications following percutaneous transluminal coronary angioplasty (PTCA), directional coronary atherectomy (DCA), and stenting.

BACKGROUND

The FVII Arg353Gln mutation decreases FVII activity, and presence of the Gln353 allele could be protective against thrombus formation during catheter interventions.

METHODS

A total of 666 consecutive patients with coronary artery disease who had undergone PTCA (n = 280), DCA (n = 104), or stenting (n = 282) were followed up for a 30-day composite end point, which included need for target vessel revascularization, myocardial infarction, and death. The Arg353Gln polymorphism of FVII was determined by PCR/RFLP assay.

RESULTS

Carriers of the Gln353 allele had significantly lower levels of total FVII activity (FVIIc, -20.7%, p < 0.001) and of activated circulating FVII (FVIIa, -32.7%, p = 0.03) compared with Arg353/Arg353. The composite end point occurred in 43 patients: 4 were heterozygous Arg353/Gln353, and 39 were homozygous Arg353/Arg353. The incidence of the composite end point was 2.5% in carriers of the Gln353 allele and 7.7% in Arg353/Arg353 homozygotes (p = 0.013). This corresponds to a 72% risk reduction in carriers of the Gln353 allele (relative risk: 0.28; 95% confidence interval: 0.09-0.81; p = 0.02).

CONCLUSIONS

The Gln353 allele of FVII is associated with substantial risk reduction in adverse events that complicate coronary catheter interventions. With the perspective of active site-blocked activated FVII (FVIIai) as conjunctive medication, the results suggest that the FVII genotype should be taken into due consideration in assessment of FVIIai medication and of its dosage.

Polymorphisms in the factor VII gene and the risk of myocardial infarction in patients with coronary artery disease

BACKGROUND

High plasma levels of coagulation factor VII have been suggested to be predictors of death due to coronary artery disease. Since polymorphisms in the factor VII gene contribute to variations in factor VII levels, such polymorphisms may be associated with the risk of myocardial infarction, which is precipitated by thrombosis.

METHODS

We studied a total of 444 patients, 311 of whom had severe, angiographically documented coronary atherosclerosis. Of these 311 patients, 175 had documentation of a previous myocardial infarction. As a control group, 133 patients with normal coronary arteriograms were also included. We measured the levels of activated factor VII and assessed three polymorphisms in the factor VII gene, one involving the promoter (A1 and A2 alleles), one involving the catalytic region (R353Q), and one involving intron 7.

RESULTS

Each of the polymorphisms influenced factor VII levels. Patients with the A2A2 and QQ genotypes had the lowest levels of activated factor VII (66 percent and 72 percent lower, respectively, than the levels in patients with the wild-type genotypes). The frequencies of the various genotypes in the patients free of coronary artery disease were similar to those in the entire population of patients with coronary artery disease. In the latter group, there were significantly more heterozygotes and homozygotes for the A2 and Q alleles among those who had not had a myocardial infarction than among those who had had an infarction (P=0.008 for the presence of the promoter polymorphism and P=0.01 for the presence of the R353Q polymorphism by chi-square analysis). The adjusted odds ratio for myocardial infarction among the patients with the A1A2 or RQ genotype was 0.47 (95 percent confidence interval, 0.27 to 0.81).

CONCLUSIONS

Our findings suggest that certain factor VII genotypes have a role in protection against myocardial infarction. This may explain why some patients do not have myocardial infarction despite the presence of severe coronary atherosclerosis.

Twenty two novel mutations of the factor VII gene in factor VII deficiency

Factor VII is a vitamin K-dependent coagulation protease essential for the initiation phase of normal hemostasis. The human factor VII gene (FVII, also known as F7) spans 13 kb and is located on chromosome 13, 2.8 kb upstream of the factor X gene. In the Greifswald FVII deficiency study the molecular basis for inherited factor VII was investigated. All exons, exon-intron boundaries and the promotor of the FVII gene were amplified by PCR and directly sequenced. 87 unrelated probands with reduced or low FVII activities were investigated. Thirty-four different FVII gene lesions were analyzed in 101 FVII alleles of 77 unrelated probands. Twenty-two of these FVII gene lesions are novel FVII variations. The 34 different lesions comprise 31 point mutations and three small deletions. A transition in the CpG doublet accounted for 12 of the 34 different mutants. Sixteen mutations were noted only once. The missense mutation A294V and the double mutation A294V; 11128delC in exon 8 were by far the most common mutations found in this study. The haplotype of the different mutant FVII alleles were analyzed using six polymorphisms of the FVII gene. The haplotypes were identified in 29 mutant FVII alleles. Five different haplotypes are linked to the mutant FVII alleles. Except for one, the same haplotype was detected in FVII genes with an identical FVII gene mutation. Different haplotypes were identified in two patients with the mutant allele A206T. It is likely that identical mutant FVII alleles with the same haplotype share the same origin.

Modulation of factor VII levels by intron 7 polymorphisms: population and in vitro studies

Previous studies have established that factor VII gene (F7) polymorphisms (5′F7 and R353Q) contribute about one-third of factor VII (FVII) level variation in plasma. However, F7 genotyping in patients with cardiovascular disease has produced conflicting results. Population and expression studies were used to investigate the role of intron 7 (IVS7 ) polymorphisms, including repeat and sequence variations, in controlling activated FVII (FVIIa) and antigen (FVIIag) levels. Genotype–phenotype studies performed in 438 Italian subjects suggested a positive relation between the IVS7 repeat number and FVII levels. The lowest values were associated with theIVS7 + 7G allele. The screening of 52 patients with mild FVII deficiency showed an 8-fold increase in frequency (8%) of this allele, and among heterozygotes for identical mutations, lower FVII levels were observed in the IVS7 + 7G carriers. This frequent genetic component participates in the phenotypic heterogeneity of FVII deficiency. The evaluation of the individual contribution of polymorphisms was assisted by the expression of each IVS7variant, as a minigene, in eukaryotic cells. The novel quantitative analysis revealed that higher numbers of repeats were associated with higher mRNA expression levels and that the IVS7 + 7Gallele, previously defined as a functionally silent polymorphism, was responsible for the lowest relative mRNA expression. Taken together, these findings indicate that the IVS7 polymorphisms contribute to the plasmatic variance of FVII levels via differential efficiency of mRNA splicing. These studies provide further elements to understand the control of FVII levels, which could be of importance to ensure the hemostatic balance under pathologic conditions.

Modulation of factor VII levels by intron 7 polymorphisms: population and in vitro studies

Previous studies have established that factor VII gene (F7) polymorphisms (5′F7 and R353Q) contribute about one-third of factor VII (FVII) level variation in plasma. However, F7 genotyping in patients with cardiovascular disease has produced conflicting results. Population and expression studies were used to investigate the role of intron 7 (IVS7 ) polymorphisms, including repeat and sequence variations, in controlling activated FVII (FVIIa) and antigen (FVIIag) levels. Genotype–phenotype studies performed in 438 Italian subjects suggested a positive relation between the IVS7 repeat number and FVII levels. The lowest values were associated with theIVS7 + 7G allele. The screening of 52 patients with mild FVII deficiency showed an 8-fold increase in frequency (8%) of this allele, and among heterozygotes for identical mutations, lower FVII levels were observed in the IVS7 + 7G carriers. This frequent genetic component participates in the phenotypic heterogeneity of FVII deficiency. The evaluation of the individual contribution of polymorphisms was assisted by the expression of each IVS7variant, as a minigene, in eukaryotic cells. The novel quantitative analysis revealed that higher numbers of repeats were associated with higher mRNA expression levels and that the IVS7 + 7Gallele, previously defined as a functionally silent polymorphism, was responsible for the lowest relative mRNA expression. Taken together, these findings indicate that the IVS7 polymorphisms contribute to the plasmatic variance of FVII levels via differential efficiency of mRNA splicing. These studies provide further elements to understand the control of FVII levels, which could be of importance to ensure the hemostatic balance under pathologic conditions.

The decanucleotide insertion/deletion polymorphism in the promoter region of the coagulation factor VII gene and the risk of familial myocardial infarction

Recently, an association has been found between factor VII polymorphisms and the risk of familial myocardial infarction. To obtain a thorough evaluation of the influence of factor VII gene on the risk of myocardial infarction, we extended our analysis to the role of a decanucleotide insertion/deletion functional polymorphism (-323 0/10-bp) in the promoter region of factor VII and to possible interactions with the HVR4 intron polymorphism. We performed a case-control study of 176 patients with myocardial infarction, over 45 years, who had a familial history of arterial thrombosis and 227 control subjects without a personal or family history of cardiovascular disease. The frequency of the rare allele of 10 bp was lower in cases (0.14 95% CI, 0.10-0.17) than in controls (0.19 95% CI, 0.16-0.23; chi(2)=4.7, p=0.03). Allowing for Hardy-Weinberg equilibrium in controls and testing for association under restricted maximisation, there was a significant difference in genotype frequency between cases and controls (p=0.02). Carriers of the 10-bp allele had an odds ratio for myocardial infarction of 0.65 (95% CI, 0.37-1.12), in multivariate logistic regression analysis. Combination analysis of -323 0/10-bp and HVR4 polymorphisms shows half reduction in the risk of myocardial infarction in comparison with the reference group for all the other groups, suggesting that there was no additivity between the effect of the 10-bp and the H7 alleles. Our findings suggest that the promoter polymorphism of factor VII gene may influence the risk of familial myocardial infarction.

The -323Ins10 polymorphism for factor VII is not associated with coronary atherosclerosis in symptomatic men. The REGRESS study group

Elevated factor VII coagulant activity (FVII:C) has been associated with an increased risk of ischaemic heart disease, particularly for fatal events. Results of studies on the association between FVII:C and atherosclerosis are not consistent. FVII:C levels are influenced by several environmental factors and by genetic factors. One of the genetic factors is the -323Ins10 polymorphism in the promoter region of the factor VII gene, which is strongly related to FVII:C, and thus may be associated with ischaemic heart disease. We studied the association of this polymorphism with the severity and progression of atherosclerosis. In 511 male patients of the Regression Growth Evaluation Statin Study, the genotype for the -323Ins10 polymorphism was determined. The minimum obstruction diameter and the mean segment diameter were determined at baseline and after a 2-year follow-up period, and new lesion formation was assessed as well. Cardiovascular events were recorded. No relationship was observed between the -323Ins10 polymorphism and angiographic measures of disease progression, nor on the risk of new cardiovascular events. The results suggest that there is no association between the -323Ins10 polymorphism for factor VII and the severity or progression of coronary atherosclerosis in male patients with symptomatic coronary artery disease.

A novel polymorphism in intron 1a of the human factor VII gene (G73A): study of a healthy Italian population and of 190 young survivors of myocardial infarction

We have identified a novel polymorphism located in intron 1a of the human factor VII gene, caused by the nucleotide change G to A at position + 73. In a population of 128 healthy individuals from northern Italy, the variant A73 allele had a frequency of 0.21, whereas the frequency of the previously reported 10 bp insertion allele located at -323 in the promoter region was 0.17 and that of the Q353 allele in the catalytic region of the factor VII gene was 0. 20. In 75% of the healthy individuals, the A73 allele was present together with the 10 bp insertion and the Q353 alleles, indicating a strong linkage disequilibrium. The concomitant presence of A73 with both the 10 bp and the Q353 alleles was associated with the lowest factor VII levels, measured as coagulant activity, activated factor VII and factor VII antigen. The G73A polymorphism was also evaluated in 190 survivors of myocardial infarction who had experienced the event before the age of 45 years and in 179 individuals with a negative exercise test matched with patients for sex, age and geographical origin. Patients carrying the A73 allele associated with lower factor VII levels tended to have a lower risk of myocardial infarction (adjusted odds ratio 0.54; 95% confidence intervals 0.29-0.99). In conclusion, we found a novel variant allele in intron 1a of the human factor VII gene that is often associated in healthy individuals with the 10 bp and Q353 alleles in the promoter and catalytic region of the same gene. This intronic mutation, alone or in association with other factor VII gene polymorphisms, might confer protection against myocardial infarction in the young.

Genetic determinants of arterial thrombosis

This chapter describes examples of genetic variation involved in the function or regulation of a number of haemostatic proteins involved in the thrombotic process. In each case, the data suggest associations between genotype and disease and, particularly in the case of fibrinogen, PAI-1, Factor VII and Factor XIII, there is interaction between genotype and environment in determination of the relevant plasma level, providing a possible explanation for the differential response of individuals to their environment.

Mechanism underlying factor VII deficiency in Jewish populations with the Ala244Val mutation

We investigated a Sephardic Jewish patient with a mild bleeding diathesis whose plasma levels of factor VII coagulant activity and factor VII antigen were 7% and 9% of normal, respectively. Sequencing demonstrated homozygosity for the Ala244Val mutation and the Arg353Gln polymorphism, which is associated with a modest decrease in factor VII levels. To elucidate the mechanism by which Ala244Val reduced factor VII levels in this patient, transient transfections were performed in COS-1 cells with wild type and mutant factor VII cDNAs and factor VII antigen levels in cell lysates and conditioned media were measured. The secretion of the mutant protein (FVII244V) into the media was 20% of wild type (FVIIwt), and intracellular levels of FVII244V were 60% of FVIIwt. A construct encoding Ala244Val along with the Arg353Gln polymorphism decreased the factor VII level in the media to that observed in the patient's plasma. Pulse-chase experiments demonstrated that FVII244V did not accumulate intracellularly and that low levels of the abnormal protein were maintained throughout the chase. To test the hypothesis that FVII244V results in an unstable molecule, amino acids with smaller (Gly) or larger (Phe) side chains were substituted for Val244 by site-directed mutagenesis. Transient transfection assays with these constructs demonstrated that the side chain of amino acid 244 is crucial in maintaining a proper conformation of the molecule. We conclude that Ala244Val results in a factor VII molecule that is unstable and is probably degraded intracellularly.

Two Common Functional Polymorphisms in the Promoter Region of the Coagulation Factor VII Gene Determining Plasma Factor VII Activity and Mass Concentration

Recent studies have provided evidence for associations between common polymorphic markers in the coagulation factor VII (FVII) gene and plasma FVII levels. Here we describe two common, nonrelated, functional polymorphisms in the promoter region of the FVII gene, a G to T substitution at position −401 and a novel G to A substitution at position −402. Both polymorphisms strongly influence the binding properties of nuclear protein(s). The rare −401T allele is associated with a reduced basal rate of transcription of the FVII gene in human hepatoblastoma cells and with reduced plasma concentrations of total FVII (VIIag) and fully activated FVII molecules (VIIa). In contrast, the rare −402A allele confers increased transcriptional activity and is associated with increased plasma FVII levels. Together, the two polymorphisms explained 18% and 28% of the variation in VIIag and VIIa, respectively, in a group of 183 healthy, middle-aged men. It is concluded that these polymorphisms are important for the regulation of the plasma levels of FVII and that they are likely to be useful genetic markers to resolve the issue of whether a causal relationship exists between FVII levels and risk of coronary heart disease.

Polymorphisms of coagulation factor genes--a review

Common genetic variants of coagulation factor genes associated with differences in concentration and/or function of coagulation factors have been studied in search of variability that could explain the individual susceptibility to thrombosis and atherothrombotic diseases. The more outstanding polymorphisms in genes of factors involved in coagulation and fibrinolysis described in the literature (such as fibrinogen, factor XIII, glycoprotein IIb/IIIa, von Willebrand factor, factors VII, VIII and IX, factor V, ATIII and protein C system factors, prothrombin, PAI-1 and fibrinolytic system) are reviewed in the context of factor's structure and function and also in its proposed relevance for thrombotic and atherothrombotic risk definition.

Severe Factor VII Deficiency Due to a Mutation Disrupting an Sp1 Binding Site in the Factor VII Promoter

We have identified a point mutation in the promoter of the factor VII gene responsible for a severe bleeding disorder in a patient from a large French-Canadian family with known consanguinity. The proband has an extremely low plasma level of factor VII antigen and factor VII coagulant activity (<1 percent of normal) and suffers from hemarthroses and chronic arthropathy. Sequencing of the patient’s factor VII 5′ flanking region, intron/exon junctions, and coding regions showed a homozygous point mutation, a C to G transversion at position −94 relative to the translation start site. We show here that this mutation prevented binding of transcription factor Sp1 and of other nuclear proteins to this region of the factor VII promoter and resulted in a 20-fold reduction in reporter gene expression in HepG2 cells. These data underscore the importance of this region of the factor VII promoter for in vivo expression of the factor VII gene.

© 1998 by The American Society of Hematology.

Severe Factor VII Deficiency Due to a Mutation Disrupting an Sp1 Binding Site in the Factor VII Promoter

We have identified a point mutation in the promoter of the factor VII gene responsible for a severe bleeding disorder in a patient from a large French-Canadian family with known consanguinity. The proband has an extremely low plasma level of factor VII antigen and factor VII coagulant activity (&lt;1 percent of normal) and suffers from hemarthroses and chronic arthropathy. Sequencing of the patient’s factor VII 5′ flanking region, intron/exon junctions, and coding regions showed a homozygous point mutation, a C to G transversion at position −94 relative to the translation start site. We show here that this mutation prevented binding of transcription factor Sp1 and of other nuclear proteins to this region of the factor VII promoter and resulted in a 20-fold reduction in reporter gene expression in HepG2 cells. These data underscore the importance of this region of the factor VII promoter for in vivo expression of the factor VII gene.

© 1998 by The American Society of Hematology.

Severe Factor VII Deficiency Due to a Mutation Disrupting a Hepatocyte Nuclear Factor 4 Binding Site in the Factor VII Promoter

Although small deletions, splice site abnormalities, missense, and nonsense mutations have been identified in patients with factor VII deficiency, there have been no reports of mutations in the factor VII promoter. We investigated a girl with factor VII levels that were less than 1% of normal in association with a severe bleeding diathesis. The patient is homozygous for a T to G transversion that occurs 61 bp before the translation start site. This nucleotide is in a sequence that is an hepatocyte nuclear factor 4 (HNF-4) binding site within the factor VII promoter (ACTTTG Æ → ACGTTG). Using gel mobility shift assays, we show that the mutation disrupts the binding of HNF-4 to its cognate binding site. In growth hormone reporter gene assays, the activity of a plasmid containing the mutant promoter was 6.7% of the wild-type promoter plasmid. Although HNF-4 was able to transactivate the wild-type factor VII promoter 5.4-fold in HeLa cells, no transactivation could be shown with the mutant promoter. These findings indicate that HNF-4 exerts a major positive regulatory effect on factor VII expression and provides in vivo evidence that binding of this transcription factor is critical for normal factor VII expression.

Severe Factor VII Deficiency Due to a Mutation Disrupting a Hepatocyte Nuclear Factor 4 Binding Site in the Factor VII Promoter

Although small deletions, splice site abnormalities, missense, and nonsense mutations have been identified in patients with factor VII deficiency, there have been no reports of mutations in the factor VII promoter. We investigated a girl with factor VII levels that were less than 1% of normal in association with a severe bleeding diathesis. The patient is homozygous for a T to G transversion that occurs 61 bp before the translation start site. This nucleotide is in a sequence that is an hepatocyte nuclear factor 4 (HNF-4) binding site within the factor VII promoter (ACTTTG Æ → ACGTTG). Using gel mobility shift assays, we show that the mutation disrupts the binding of HNF-4 to its cognate binding site. In growth hormone reporter gene assays, the activity of a plasmid containing the mutant promoter was 6.7% of the wild-type promoter plasmid. Although HNF-4 was able to transactivate the wild-type factor VII promoter 5.4-fold in HeLa cells, no transactivation could be shown with the mutant promoter. These findings indicate that HNF-4 exerts a major positive regulatory effect on factor VII expression and provides in vivo evidence that binding of this transcription factor is critical for normal factor VII expression.