1/21. 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) |
2/21. A novel two base pair deletion in the factor V gene associated with severe factor v deficiency.We studied a family in which the proband, a 13-year-old boy, had unmeasurable plasma levels of coagulation factor V antigen and activity. Clinical symptoms were severe, with several episodes of haemorrhages in the mucosal tracts (gastrointestinal, nose and urinary) and recurrent haemarthroses that caused permanent arthropathy. sequence analysis of the factor V gene demonstrated the presence of a novel 2 base pair (bp) homozygous deletion in exon 13 at positions 2833-2834. This mutation, present in the heterozygous state in the asymptomatic mother and absent in the healthy brother, introduced a frameshift and a premature stop at codon 900. This would predict the synthesis of a truncated factor V molecule, lacking part of the B domain and the complete light chain. Because of the existence of a surveillance mechanism that selectively recognizes and degrades mRNA molecules carrying premature termination codons, we analysed the relative abundance of mutant vs. wild-type mRNA molecules in the platelets of the heterozygous proband's mother. The mutant mRNA was significantly reduced in amount (mutant/wild-type ratio 0.35). This is the first reported mutation in the factor V gene causing severe factor v deficiency, the effect of which was quantitatively analysed at mRNA level.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
3/21. Coexistence of a novel homozygous nonsense mutation in exon 13 of the factor V gene with the homozygous Leiden mutation in two unrelated patients with severe factor v deficiency.A novel homozygous 3571C-->T nonsense mutation predicting the synthesis of a truncated factor V (FV) molecule was identified in exon 13 of the human coagulation factor V gene in two unrelated Italian probands with undetectable plasma levels of FV antigen and activity. Both patients were also homozygous for the FV Leiden mutation. reverse transcription polymerase chain reaction studies showed strongly reduced mRNA levels of the mutant FV allele and FV heavy and light chains were not measurable in the plasma of the probands and reverse transcriptase. Haplotype analysis indicated that the nonsense mutation in both families had a common founder a long time ago.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
4/21. Homozygous factor V splice site mutation associated with severe factor v deficiency.We investigated a family whose proband has a severe bleeding disorder and factor V antigenic and functional levels of 8% and less than 1% of control values, respectively. Molecular analysis of the factor V gene revealed a novel homozygous mutation in the last nucleotide of exon 10. 1701G>T causes activation of a cryptic exonic splice site in exon 10, which encodes part of the factor V heavy chain (A2 domain). This leads to the deletion of 35 nucleotides and results in a frameshift with a premature stop codon at amino acid position 498. The G1701 and corresponding Gln509 are conserved in murine, bovine, and porcine factor V and in human factor viii. Few factor v deficiency mutations have been identified as yet. Several are present in the heterozygous form in combination with factor V Leiden (Arg506Gln). This is the first reported homozygous splice site mutation in a patient with factor v deficiency.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
5/21. Arg2074Cys missense mutation in the C2 domain of factor V causing moderately severe factor v deficiency: molecular characterization by expression of the recombinant protein.Factor V (FV) deficiency is a rare bleeding disorder whose genetic basis has been described in a relatively small number of cases. Among a total of 12 genetic defects reported in severely or moderately severe deficient patients, 3 were missense mutations and in no case was the mechanism underlying the deficiency explored at the molecular level. In this study, a homozygous missense mutation at cDNA position 6394 in exon 23 of the FV gene was identified in a 22-year-old Italian patient. This mutation causes the replacement of arginine 2074 with a cysteine residue (Arg2074Cys) in the C2 domain of the protein. The effect of the Arg2074Cys mutation on FV secretion, stability, and activity was investigated. Site-directed mutagenesis of FV cDNA was used to introduce the identified mutation, and wild-type as well as mutant FV proteins were expressed by transient transfection in COS-1 cells. An enzyme immunoassay detected low FV antigen levels both in the conditioned media of cells expressing the mutant protein and in cell lysates. Metabolic labeling and pulse-chase experiments confirmed that the mutation caused an impaired secretion of FV associated with rapid intracellular degradation. In addition, evaluation of wild-type and mutant coagulant activity demonstrated that the FV molecules carrying the Arg2074Cys mutation have reduced activity. These findings, beside confirming the structural and functional importance of the arginine 2074 residue, demonstrate that its substitution with a cysteine impairs both FV secretion and activity.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
6/21. Combined deficiency of factor V and factor viii. A report of another case.A patient with combined factor V and factor viii deficiency is presented. The bleeding manifestations were: easy bruising, post-traumatic bleeding, bleeding after tooth extractions. The main laboratory feature was a prolonged partial thromboplastin time which was corrected by the addition of adsorbed normal plasma but not by the addition of normal serum, hemophilia a plasma of another patient with combined factor V and factor viii deficiency. The thromboplastin generation test was clearly abnormal and was corrected by the addition of adsorbed normal plasma but not by addition of normal serum. Prothrombin consumption was also defective. prothrombin time was slightly prolonged too, Thrombin time, platelet and vascular tests were within normal limits and there was no hyperfibrinolysis. factor viii was 8% of normal, whereas factor V was 14% of normal. factor viii associated antigen was normal. All other clotting factors were within normal limits. The parents of the propositus were consanguineous (first cousins) but had normal factor V and factor viii activity and normal factor viii antigen. The same was true for other family members. The hereditary transmission of the condition appears autosomal recessive.- - - - - - - - - - ranking = 2keywords = antigen (Clic here for more details about this article) |
7/21. Severe factor v deficiency: exon skipping in the factor V gene causing a partial deletion of the C1 domain.BACKGROUND: Severe factor V (FV) deficiency is a rare coagulation disorder, characterized by very low or unmeasurable plasma levels of functional and immunoreactive FV. Among rare inherited coagulopathies, FV deficiency is the least characterized from a molecular point of view (only 12 mutations have been reported). OBJECTIVES: The aim of this work was to investigate, at the molecular level, the pathogenetic mechanisms responsible for a case of severe FV deficiency. patients AND methods: A 19-year-old Iranian man showing unmeasurable FV activity and severely reduced FV antigen level in plasma was studied. Mutation screening was performed by sequencing. The effect of the identified mutation was investigated both at the mRNA and at the protein level. RESULTS: Molecular analysis of the factor V (FV) gene identified a novel homozygous A-->T transversion at position 3 of the donor splice site of intron 19 (IVS19 3A-->T). Production of mutant mRNA in hela cells demonstrated that this mutation causes the entire exon 19 to be skipped from the FV mRNA. The mutant processed transcript codes for a deleted FV, lacking the first 24 amino acids of the C1 domain. Expression of the mutant FV protein in COS-1 cells showed that the deleted protein was synthesized but not secreted; moreover, the intracellular amount of deleted FV was reduced compared to wild type, suggesting intracellular degradation of mutant FV. CONCLUSIONS: This work reports the molecular characterization of the first mutation causing a partial deletion in the FV molecule, resulting in a severe impairment of protein secretion.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
8/21. Anti-factor V auto-antibody in the plasma and platelets of a patient with repeated gastrointestinal bleeding.Development of autoantibody against coagulation factor V (FV) is a rare clinical condition with hemorrhagic complications of varying severity. The aim of this study was to establish the pathomechanism of an acquired FV deficiency and characterize the FV inhibitor responsible for the clinical symptoms. A 78-year-old female was admitted to hospital with severe gastrointestinal bleeding. General clotting tests and determination of clotting factors were performed by standard methods. FV antigen and FV containing immune complexes were measured by ELISA. The FV molecule was investigated by Western blotting and by sequencing the f5 gene. The binding of patient's IgG to FV and activated FV (FVa) was demonstrated in an ELISA system and its effect on the procoagulant activity of FVa was tested in clotting tests and in a chromogenic prothrombinase assay. Localization of the epitope for the antibody was performed by blocking ELISA. FV activity was severely suppressed both in plasma and platelets. FV antigen levels were normal by ELISA using polyclonal anti-FV antibody or monoclonal antibody against the connecting region of FV, but depressed when HV1 monoclonal antibody against the C2 domain in the FV light-chain was used as capture antibody. The FV molecule was found intact. An IgG reacting with both FV and FVa was present in the patient's plasma and its binding to FV was inhibited by HV1 antibody. FV-containing immune complexes were detected in the patient's plasma and platelet lysate. The patient's IgG inhibited the procoagulant function of FVa. An anti-FV IgG was present in the patient's plasma and platelets. The autoantibody reacted with an epitope in the C2 domain of FV light chain and neutralized the procoagulant function of FVa.- - - - - - - - - - ranking = 2keywords = antigen (Clic here for more details about this article) |
9/21. A case of coagulation factor v deficiency caused by compound heterozygous mutations in the factor V gene.We investigated the molecular basis of a severe factor V (FV) deficiency in a Japanese female, and identified two distinct mutations in the FV gene, a novel cytosine insertion (1943insC) and a previously reported point mutation (A5279G). We expected the patient to be a compound heterozygote for those mutations, as a 1943insC, but not an A5279G, was found in the mother and a sibling. The 1943insC will cause a frame-shift after 590Gln, resulting in amino acid substitutions with two abnormal residues followed by a stop codon in the FV A2 domain (FS592X). The A5279G will cause an amino acid alteration in the FV A3 domain (Y1702C), which has been observed in several ethnic groups. We found that both mutant mRNAs were detected by reverse transcriptase polymerase chain reaction (RT-PCR) in the patient's platelets, whereas no FV antigen and activity were detected in plasma. On the one hand, the RT-PCR signal from the FS592X-FV mutant mRNA was markedly reduced, suggesting that the rna surveillance system would eliminate most of the abnormal FS592X-FV transcripts with a premature termination. On the other hand, expression analyses revealed that only small amounts of Y1702C-FV with a low specific activity were secreted, and that the FS592X-FV was not detected in cultured media. These data indicated that both mutant FV molecules would be impaired, at least in part, during the post-transcriptional process of protein synthesis and/or in secretion. Taken together, it seems to suggest that each gene mutation could be separately responsible for severe FV deficiency, while this phenotype is due to the in-trans combination of the two defects.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
10/21. A case of congenital factor v deficiency combined with multiple congenital anomalies: successful management of palatoplasty.A patient with congenital factor v deficiency combined with mental retardation and several congenital anomalies including cleft palate, dwarfism, microcephaly and right hydrocele testis is described. The levels of factor V activity and factor V antigen of plasma were significantly decreased. The platelet lysate obtained from him also showed a significantly low level of factor V activity. Palatoplasty and tooth extraction were successfully performed under transfusion therapy with fresh-frozen plasma.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
| | Next -> |