Structural and functional characterization of novel F7 mutations identified in Chinese factor VII-deficient patients.

Hereditary factor VII (FVII) deficiency is a rare recessive bleeding disorder with an estimated prevalence of 1/500 000. We had investigated 50 unrelated Chinese patients with FVII deficiency and identified, in total, 25 mutations, including 18 missense mutations and 5 splicing mutations, on the F7 gene. The nucleotide transition c.1224T>G (p.His408Gln) in exon 9 constitutes a hotspot of mutation, with 19 patients harbouring this genetic variance. Few patients were homozygous or compound heterozygous for deleterious mutations, such as non-sense mutations, large insertion or deletions, indicating that complete deficiency of FVII may not be compatible with life. The eight novel mutations identified in the study, including one small deletion (p.Glu49GlyfsTer101), three type I missense mutations, p.Cys238Phe, p.Gly420Asp, p.Ala252Val and four type II missense mutations, p.Val336Met, p.Ser342Gly, p.Gly432Ser and p.Ile213Asn, were further analysed by in vitro expression and functional studies. The laboratory phenotype and structural analysis confirmed the functional consequence of p.Ile213Asn mutation involving cleavage and activation site. The molecular dynamic simulations and binding energy calculations along with functional probing of p.Gly432Ser mutation revealed the critical role of residue Gly432 in the binding between activated factor VII (factor VIIa) and tissue factor.

Analysis of Phenotype and Genotypein an Inherited Coagulation Factor VII Deficiency Pedigree.

BACKGROUND: To identify potential mutations and analyze the phenotype in an inherited factor VII (FVII) deficiency pedigree. METHODS: Prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, FVII activity (FVII:C), FVII antigen (FVII:Ag) and other coagulant parameters of the proband and family members were measured. Calibrated automated thrombin generation measurements were used to detect coagulation status. All the exons, exonintron boundaries and 5', 3' untranslated sequences of the F7 gene in the proband and other family members were amplified by polymerase chain reaction (PCR). The PCR products were screened by direct sequencing. The detected mutations were confirmed by sequencing the other strand and analyzed by PIC software. RESULTS: The PT in the proband was prolonged and further study showed that the FVII:C and FVII:Ag were below the normal range, 3% and 38%, respectively. Double heterozygous mutations in the proband were identified: an A to G mutation at position 11,459 in exon 8, resulting in a p.Lys341Glu substitution, and a 2bp deletion (nt 27 del CT) mutation in exon 1a, leading to a frameshift and the creation of a premature stop codon. Both endogenous thrombin potential (ETP) and peak height in the proband were declined. Her father, brother, daughter, son, and niece were heterozygous for the nt 27 del CT mutation, while her mother, little brother, little niece, and little nephew were heterozygous for the Lys341Glu mutation, and their ETP and peak height obtained more than half normal ETP and peak height, respectively. Model analysis indicated that the Lys341Glu mutation will interrupt the electrovalent bond between 341Lys and 289Asp. CONCLUSIONS: Compound heterozygous mutations (p.Lys341Glu and nt27 del CT) which were responsible for the bleeding tendency were found in a pedigree of inherited FVII deficiency. The Lys341Glu mutation is firstly reported and nt27 del CT may be one of the mutational spots in Chinese population.

Clinical and Laboratory Findings in Jewish and Bedouin Patients in Southern Israel Who Were Diagnosed with Factor VII Deficiency.

BACKGROUND: Congenital factor VII deficiency is a rare recessive autosomal bleeding disorder with a wide spectrum of clinical manifestations. OBJECTIVES: To compare the clinical and laboratory findings in Jewish and Bedouin patients with factor VII deficiency. METHODS: The clinical and laboratory findings of patients with factor VII deficiency treated at Soroka Medical Center, a tertiary hospital in Israel, from 2005 to 2015 were analyzed regarding blood factor levels, illness severity, treatment administration, and disease outcome. RESULTS: Seventy-eight patients were enrolled (1:13,000 of the population in southern Israel) of whom 26 were diagnosed with severe factor VII deficiency (1:40,000). Sixty (76.9%) patients were Jewish and 18 (23.1%) were Bedouin. In univariable analysis, Bedouin patients exhibited a more severe illness, with significantly higher complication and fatality rates, and required more preventive treatment than the Jewish patients. CONCLUSIONS: The prevalence of congenital factor VII deficiency (including severe deficiency) in the Jewish and Bedouin populations of southern Israel is higher than previously reported. The clinical spectrum of the disease was found to be more severe in the Bedouin population.

Hemophagocytic lymphohistiocytosis and congenital factor VII deficiency: a case report.

BACKGROUND: Hemophagocytic lymfohistiocytosis (HLH) is a rare, life-threatening hyperinflammation, characterized by immune system over-activation resulting in hemophagocytosis. HLH could appear as a primary disease caused by mutations of immune-regulatory genes, or develop as a result of viral or bacterial infections, or malignancy. Congenital factor VII (FVII) deficiency is a rare autosomal recessive disorder characterized by prolonged prothrombin time (PT) and low FVII, which may increase bleeding risk. CASE PRESENTATION: A 50-year-old woman was admitted for a fever persisted for 20 days, presenting with cytopenia, high hyperferritinemia, low activity of NK cells. Bone marrow aspiration showed hemophagocytosis. CT scanning found pulmonary infection. EBV and CMV were not detected. Genetic scanning did not find pathogenic mutation of a HLH NGS panel including 26 genes. This patient was treated as recommended by the HLH 2004 Guidelines. Coagulation tests identified FVII deficiency. Genetic analysis of F7 gene in the patient and her family members identified recurrent compound heterozygous F7 c.64 + 5G > A and c.1224 T > G (p.His408Gln) mutations in this patient and her brother who showed postoperative hemorrhage after surgical resection of renal cell carcinoma. Heterozygotes in this family were asymptomatic. CONCLUSIONS: To our knowledge, this is the first report of HLH in combination with congenital FVII deficiency in Chinese population.

Frequencies of mild factor V, VII and X deficiencies in a Japanese population.

We investigated the frequencies of coagulation factor deficiencies in a Japanese population. We measured factor II, V, VII and X activity in 100 healthy individuals. A specific factor deficiency was determined according to the factor activity and the ratio of the factor activity to that of other coagulation factors. Seven samples showed factor activity less than the mean -2SD of standardized factor activity (factor II: three; factor V: one; factor VII: one; factor X: one and factor V+factor VII: one). The samples with low factor II and factor VII activity were determined not to be due to deficiency because the ratios of these factor activities to other factor activities were within the range of the mean +/- 2SD. We measured activity ratios in the remaining 97 samples and identified one sample with factor V deficiency and two with factor VII deficiency. Thus, six samples with coagulation factor deficiency were identified (factor X: one; factor V: two; factor VII: two and factor V + factor VII: one). These results suggest that the Japanese population has relatively high frequencies of mild factor V, factor VII and factor X deficiencies, in which activity is reduced to approximately 50% (36-64%) of normal plasma.

Age estimates of ancestral mutations causing factor VII deficiency and Dubin-Johnson syndrome in Iranian and Moroccan Jews are consistent with ancient Jewish migrations.

Factor VII (FVII) deficiency and Dubin-Johnson syndrome (DJS) are rare autosomal recessive disorders caused by mutations in F7 and MRP2 genes, respectively. Both disorders are relatively frequent among Iranian and Moroccan Jews. FVII deficiency in both populations is caused by a founder A244V mutation in the F7 gene and DJS is caused by two founder mutations, I1173F and R1150H in the MRP2 gene that are specific for Iranian and Moroccan Jewish patients, respectively. We estimated the age of FVII A244V and MRP2 I1173F by analysis of microsatellite markers flanking F7 and MRP2 genes, respectively, in 13 Iranian Jewish homozygotes for the I1173F mutation and 21 Iranian and Moroccan Jewish homozygotes for the A244V mutation. Dating of the mutations was estimated by the DMLE+2.0 program employing observed linkage disequilibria of multiple genetic markers. The estimated age of the I1173F mutation was approximately 1500 years, and the age of the A244V mutation was approximately 2600 years. These estimates suggest that I1173F causing DJS in Iranian Jews occurred after the separation of Iranian Jews from Moroccan Jews 2000-2600 years ago, while A244V causing FVII deficiency in Iranian and Moroccan Jews occurred prior to the divergence of these two populations.

Prevalence of factor VII deficiency and molecular characterization of the F7 gene in Brazilian patients.

The prevalence of factor VII (FVII) deficiency in 267 Brazilian patients was estimated to be 4.1%, including one patient with significant bleeding, five with minor bleeding and five patients asymptomatic. Only one novel mutation 8926G <-- T (I140S) was seen in one patient. The other mutations were 10828G <-- A (R304Q) in three patients, 10846G <-- T (C310F) in one patient, and 10909G <-- A (G331D) in one patient. Except for one homozygous patient (C310F) with a severe deficiency, only one allele was affected in all other instances. An inverse association between F7 polymorphisms and FVII activity were found in these patients, as those with higher levels of FVII activity presented the genotype described in the literature as related to reduced FVII activity. As the R304Q mutation was the most frequent in these patients, and may be associated with an asymptomatic form of the disease, particularly in Blacks, we examined this mutation and FVII activity in 49 Blacks and 49 Caucasian blood donors with no clinical bleeding. None of the individuals showed the R304Q mutation, and FVII activity was normal in all of them, thus indicating that FVII deficiency is not common in normal individuals of these two ethnic groups in Brazil. This is the first study in South America to examine the prevalence and molecular basis of FVII deficiency, including the description of a novel mutation.

Genotype associations of factor VII gene with plasma factor VII coagulant activity and antigen levels in healthy Chinese.

A raised plasma factor VII (FVII) level is one of the risk factors for coronary artery disease. The R353Q polymorphism at codon 353 and the 10 base pair (bp) insertion (0/10 bp) polymorphism of the FVII gene have been reported to be associated with plasma FVII levels in several populations. We investigated these two polymorphisms in 209 male and 214 female healthy Chinese. The allele frequencies of 10 bp and Q were 0.036 and 0.045, respectively. Strong linkage disequilibrium was observed between these two sites (Delta = 0.85, P < 0.001). There were significant genotype associations of these two loci with FVII coagulant activity (FVIIc) and antigen (FVIIAg) levels. Heterozygous individuals had lower FVIIc and FVIIAg levels than those homozygous for the common alleles. When analyzed separately by gender, the 0/10 bp polymorphism was strongly associated with FVIIAg levels in males and females. However, both polymorphisms were significantly associated with FVIIc levels only in the females. The effect of 0/10 bp polymorphism predominated over that of the R353Q polymorphism in a two-way analysis of variance procedure. In the Chinese, the 10 bp insertion may reduce transcription of the FVII gene, leading to the decreased synthesis of FVII protein and thus FVIIc.

Apparently dominant transmission of a recessive disease: deficiency of factor VII in Iranian Jews.

In inherited disorders transmitted as autosomal recessive traits the children of affected individuals are usually asymptomatic and phenotypically normal because they are heterozygous for the defect. In an Iranian Jewish family with moderately severe deficiency of coagulation factor VII (an autosomal recessive bleeding disorder) the son of an affected woman was also affected. DNA analysis of the factor VII gene showed that this unusual situation was due to the fact that he inherited an abnormal allele with the Ala244Val missense mutation from both the homozygous mother and the heterozygous father. The parents, although not overtly consanguineous, belong to the same ethnic group of Iranian Jews, among whom this factor VII gene mutation reaches high frequencies (between 2 and 3%) in the heterozygous state.

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.

Characterization of a factor VII molecule carrying a mutation in the second epidermal growth factor-like domain.

A missense mutation at codon 100 in the second epidermal growth factor-like domain, resulting in Gln100-->Arg, was detected in 19 out of 21 available severely factor VII (FVII) deficient patients in Norway. Seventeen patients were homozygous, and the two remaining were compound heterozygotes. In the homozygous patients, FVII antigen was measured to 10-28%, and activity to 0.6-6.5% of that in normal pooled plasma. Recombinant FVII containing the mutation was expressed transiently in CHO cells to a mean antigen level of 57% of the wild type FVII protein, and with a specific activity of 6% of wild type. The mutant protein had a 14-fold reduction in affinity for tissue factor (TF), whereas binding of FX seemed unaffected. In line with the experimental data, molecular modelling of the mutation based on the coordinates of the tissue factor/FVIIa complex showed that substituting arginine for glutamine disrupts the interface between the catalytic and second epidermal growth factor-like domains.

Ala244Val is a common, probably ancient mutation causing factor VII deficiency in Moroccan and Iranian Jews.

We investigated the molecular basis for factor VII (FVII) deficiency in Israel and found that 13 patients were homozygous and 10 heterozygous for a C to T substitution at nucleotide 10648 of the FVII gene. This predicted an Ala244Val change and was associated with decreased FVII activity and antigen level. Of the 36 Ala244Val positive alleles, 20 were observed in patients of Moroccan origin, 10 in Iranian-Jewish patients and 6 in patients of other origins. A computer model of the serine protease domain of FVII suggested that the Ala244Val substitution may cause distortion of the entire protein structure. Intragenic polymorphic sites analyses disclosed a founder effect for the Moroccan and Iranian-Jewish patients. A survey of the Ala244Val mutation revealed an allele frequency of 1:42.5 in Moroccan Jews and 1:40 in Iranian Jews. As Moroccan Jews have been separated from Iranian Jews for more than two millennia, the data suggest that the Ala244Val mutation occurred in ancient times.