1/35. life-threatening bleeding in a case of autoantibody-induced factor vii deficiency.A male patient presented with life-threatening bleeding induced by autoantibody-induced factor VII (F.VII) deficiency. This patient had macroscopic hematuria, skin ecchymosis, gastrointestinal bleeding, and a neck hematoma that was causing disturbed respiration. He developed acute renal failure and acute hepatic failure, probably due to obstruction of the ureters and the biliary tract, respectively. Although activated partial thromboplastin time was normal, prothrombin time (PT) was remarkably prolonged at 71.8 seconds compared to 14.0 seconds in a normal control. Both the immunoreactive level of F.VII antigen and the F.VII activity of the patient's plasma samples were < 1.0% of normal. Although an equal part of normal plasma was added to the patient's plasma, PT was not corrected. The patient's plasma inhibited F.VII activity. These findings suggested the presence of a plasma inhibitor for F.VII. After administration of large doses of methylprednisolone, PT was gradually shortened and plasma levels of F.VII increased over time. Bleeding, acute renal failure, and acute hepatic failure improved markedly following the steroid treatment. These observations suggest that life-threatening bleeding can be induced by autoantibody-induced F.VII deficiency and that immunosuppressive therapy using large doses of steroid can be successful in inhibiting the production of the autoantibody.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
2/35. 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.- - - - - - - - - - ranking = 2keywords = antigen (Clic here for more details about this article) |
3/35. Combined factor V and factor vii deficiency due to an independent segregation of the two defects.A patient with combined factor V and factor vii deficiency is described together with a family study. The propositus appeared to be double heterozygous for factor V and factor vii deficiency. Since the patient showed a parallel decrease of activity and antigen, he appeared to be double heterozygous for a true deficiency. The patient had inherited the factor V defect from the mother and the factor VII defect from the father. The parents of the propositus were not consanguineous. Other family members were found to have isolated factor V or factor vii deficiency. This is the third family so far described with this peculiar combined defect but the first to be investigated by clotting and immunologic assays.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
4/35. Severe factor vii deficiency caused by a novel mutation His348 to Gln in the catalytic domain.Factor VII is a vitamin k-dependent zymogen that plays a key role in the initiation of the extrinsic pathway. A severe factor vii deficiency was identified in a 45-year old male whose plasma factor VII antigen was less than 60 ng/ml and expressed 5.2% of normal factor VII activity. dna sequence analysis of the patient's factor VII gene showed a thymidine to guanine transversion at nucleotide 10968 in exon VIII that results in a novel amino acid substitution of His348 to Gln. The patient was homozygous for this mutation, whereas some of his family members were heterozygous. Both wild type and mutant factor VII were transiently expressed in COS-1 cells. The level of secreted mutant factor VII antigen was only 11.0% of the level of wild type factor VII. In cho cells stably transfected with the mutant factor VII, only 37.3% of the total labeled FVII was secreted into the conditioned media and the remainder was retained inside the cells. These data suggest this mutation leads to factor vii deficiency due to the impaired secretion of the molecule.- - - - - - - - - - ranking = 2keywords = antigen (Clic here for more details about this article) |
5/35. Factor VII R110C: a novel missense mutation (Arg110Cys) in the second epidermal growth factor-like domain causing factor vii deficiency in members of a Japanese family.This report describes the findings of a genetic analysis of the factor VII (FVII) gene in a Japanese, male patient with FVII deficiency. The proband showed FVII activity level of 25% and FVII antigen level of 28% of the normal value, but he had no severe bleeding episodes. We identified the mutation by direct sequencing of polymerase chain reaction products representing all exons except 1b and their flanking intronic regions of his FVII gene. We detected a single point mutation, a C-->T substitution at nucleotide position 7863 in exon 5, which results in an amino acid replacement of Arg (CGC) to Cys (TGC) at codon 110 in the second epidermal growth factor-like domain. Homozygosity was confirmed in the propositus by loss of a site for the restriction endonuclease Eco47III. Furthermore, his parents, who had moderately reduced levels of factor VII activity and antigen, carried this mutation site as a heterozygote. Although the Arg11O residue is located distal to the tissue factor (TF) in the soluble TF-FVIIa crystal structure, we infer that the replacement of the positively charged and larger Arg residue with a neutral Cys residue may be likely to impair proper folding, resulting in destabilization of the protein structure.- - - - - - - - - - ranking = 2keywords = antigen (Clic here for more details about this article) |
6/35. Abnormal secretion and function of recombinant human factor VII as the result of modification to a calcium binding site caused by a 15-base pair insertion in the F7 gene.A case of a novel mutation in the F7 gene that results in factor VII coagulant activity (VII:c) of less than 1% and VII antigen (VII:Ag) levels of 10% is presented. dna analysis revealed a homozygous 15-base pair (bp) in-frame insertion-type mutation at nucleotide 10554. This insertion consisted of a duplication of residues leucine (L)213 to aspartic acid (D)217 (leucine, serine, glutamic acid, histidine, and aspartic acid), probably arising by slipped mispairing between 2 copies of a direct repeat (GCGAGCACGAC) separated by 4 bp. Molecular graphic analyses showed that the insertion is located at the surface of the catalytic domain in an exposed loop stabilized by extensive salt-bridge and hydrogen bond formation at which the calcium binding site is located. The mutation probably interferes with protein folding during VII biosynthesis and/or diminishes functional activity through the loss of calcium binding. in vitro expression studies demonstrated that the levels of VII:Ag in lysates of cells transfected with wild type VII (VIIWT) were equivalent to those with mutant type VII (VIIMT), but the level of secreted VIIMT was 5% to 10% that of VIIWT. pulse chase studies demonstrated that VIIMT did not accumulate intracellularly, and studies with inhibitors of protein degradation showed that recombinant VIIMT was partially degraded in the pre-Golgi compartment. Accordingly, only small amounts of VIIMT with undetectable procoagulant activity were secreted into conditioned media. These results demonstrate that a combination of secretion and functional defects is the mechanism whereby this insertion causes VII deficiency.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
7/35. Severe factor vii deficiency with recurrent intracranial haemorrhages owing to double heterozygosity for a splice site mutation of an IVS4 and a novel nonsense mutation in exon 8 (Gln211-->Term).Genetic analysis of a 10-month-old Japanese baby boy with recurrent intrathoracic bleeding, cerebral haemorrhages and gastrointestinal bleeding secondary to severe factor VII (FVII) deficiency revealed evidence of two distinct mutations of FVII: a splice site mutation of G-->A at nucleotide 6071 in the IVS4 splice site and a novel nonsense mutation (Gln211-->Term) in exon 8. His bleeding was difficult to control without prophylactic infusion of FVII. We detected a heterozygous splice site mutation of the IVS4 in his mother and a heterozygous nonsense mutation in exon 8 (Gln211-->Term) in his father. The parents' FVII levels are both 50% of normal controls. The FVII:C in plasma from the proband was < 1.5% of normal controls. FVII:antigen (Ag) was < 1% of normal controls, using a monoclonal antibody (mAb) hVII-B101/1 that specifically reacts with FVII epidermal growth factor 1 (EGF-1), and 5% of normal controls, using a rabbit polyclonal antibody against human FVII. After immunoadsorption with mAb hVII-B101/B1-sepharose 4B, FVII levels of both the proband and his mother were 5% of normal controls; after immunoadsorption the FVII levels of normal subjects were < 1%. We hypothesize that secretion of a small amount of dysfunctional FVII lacking EGF-1 into the circulation accounts for this observation.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
8/35. Human factor vii deficiency caused by S339C mutation located adjacent to the specificity pocket of the catalytic domain.This report documents our identification of a novel factor VII (FVII) gene mutation in a Japanese boy with FVII deficiency. The proband's FVII activity was 34% and his FVII antigen level was 40% of normal controls. dna sequence analysis of the proband's FVII gene identified a C to G point mutation at nucleotide position 10 933 in exon 8, which results in the substitution of Cys (TGC) for Ser339 (TCC). Hinf I digestion results indicate the proband and his mother were heterozygous for the mutation. Both wild-type and mutant FVIIs were transiently expressed in COS-1 cells. FVII levels measured in the culture medium of FVII Ser339Cys mutants were markedly reduced as compared to those of cells with FVII wild-type. The amount of intracellular FVII in FVII Ser339Cys mutants was 80% of that in wild-type. In the wild-type FVII, Ser339 is juxtaposed to Asp338, which is positioned at the bottom of the substrate-binding pocket in the protease domain and located adjacent to FVII Cys340, that forms a disulphide bond with Cys368. We suspect that the creation of a novel unpaired cysteine through this mutation leads to abnormal disulphide bonding during protein folding, thereby reducing the secretion of FVII.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
9/35. 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.- - - - - - - - - - ranking = 3keywords = antigen (Clic here for more details about this article) |
10/35. A novel congenital haemostatic defect: combined factor VII and factor xi deficiency.Isolated deficiencies of factors VII and XI are both rare. Not surprisingly, therefore, combined factor VII and XI deficiency has not been reported previously. We report here a kindred with a combined heterozygous deficiency for both factors VII and XI. The proposita is a 28-year-old woman who had both a prolonged prothrombin time (PT) and a prolonged activated partial prothrombin time (APTT) associated with a mild bleeding tendency. Coagulation studies were performed on the six available members of this kindred. The PT and APTT were normal or mildly abnormal in five of these individuals. Factor VII coagulant activity (VII:C) varied from 0.33 to 0.77 units/ml in affected subjects. In contrast, the concentration of factor VII-related antigen for the six individuals ranged from 0.68 to 2.10 units/ml. Comparable factor VII:C levels were obtained when each subject's plasma was tested with either a rabbit or a human thromboplastin reagent. Factor XI coagulant activity was less than 0.5 units/ml in three of the six subjects and normal (approximately 1.0 units/ml) in the other three. The concentrations of thrombin-antithrombin-III and prothrombin fragment 1.2 were within normal limits for all individuals. In addition to being associated with heterozygous factor xi deficiency, the abnormal factor VII molecule in the plasma of affected individuals in this kindred appears to represent a newly described mutation. This is suggested by the pattern of reactivity with thromboplastin from different species, the normal tissue factor binding and the bleeding tendency in heterozygous individuals in this kindred.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
| | Next -> |