1/16. Hypofibrinogenemia associated with a heterozygous missense mutation gamma153Cys to arg (Matsumoto IV): in vitro expression demonstrates defective secretion of the variant fibrinogen.We genetically analyzed a case of hypofibrinogenemia that showed no bleeding or thrombotic tendency. Direct sequencing of a polymerase chain reaction-amplified gamma-chain gene segment showed a novel nucleotide substitution. This heterozygous mutation encodes both Cys (TGT) and Arg (CGT) at residue 153. To examine the basis for the fibrinogen deficiency, we prepared expression vectors containing mutant gamma-chain DNAs encoding gamma153R and gamma153A for in vitro expression in Chinese hamster ovary (CHO) cells. enzyme-linked immunosorbent assay and immunoblot analysis of the culture media and cell lysates showed that cho cells transfected with gamma153R or gamma153A synthesized the variant gamma-chain, but did not secrete variant fibrinogen into the culture medium. Metabolic pulse-chase experiments showed that fibrinogen assembly was impaired when either variant gamma-chain was expressed. In cells expressing normal fibrinogen, assem- bly intermediates and intact fibrinogen were seen in cell lysates prepared after short (3 minutes) or long (1 hour) incubation with (35)S-methionine. Neither intermediates nor intact fibrinogen was seen with the variant gamma-chains. These data suggest that gamma-chains have an important early role in fibrinogen assembly. Thus, our results support the model for fibrinogen assembly proposed by Huang et al (J Biol Chem 268:8919, 1993), in which the first step in assembly is the formation of alphagamma or betagamma dimers, or both. This model implies that gammaCys153 has a critical role in the formation of these early assembly intermediates. We concluded that the gamma153Cys-->Arg substitution does not allow fibrinogen assembly and secretion, and this is manifest in vivo as a fibrinogen deficiency. We designated this variant as fibrinogen Matsumoto IV.- - - - - - - - - - ranking = 1keywords = deficiency (Clic here for more details about this article) |
2/16. leg ulcer presenting in a patient with congenital afibrinogenaemia.Congenital afibrinogenaemia is a rare hemorrhagic disorder characterized by the absence of fibrinogen. We report a case of congenital afibrinogenaemia presented with leg ulcer. A 30-year-old man presented with a history of prolonged bleeding from birth. His parents are cousins. He repeatedly showed haematoma after traumas on his leg. He was diagnosed as having congenital afibrinogenaemia because of plasma fibrinogen deficiency. Because his leg ulcer gradually increased in size, he was admitted to our department for treatment. Laboratory examinations revealed prolonged bleeding time, prolonged coagulation time, prolonged prothrombin time, prolonged activated partial thromboplastin time and plasma fibrinogen was not measurable. Histological examination revealed hyperkeratosis, acanthosis and severe fibrotic change in the whole dermis. Severe hemosiderin deposit was found in the middle dermis. His leg ulcer cured 2 months after the beginning of fresh frozen plasma administration (FFP), but recurrence of the leg ulcer after FFP treatment was found. This is the second reported case of congenital afibrinogenaemia presented with leg ulcer.- - - - - - - - - - ranking = 0.5keywords = deficiency (Clic here for more details about this article) |
3/16. Identification of simultaneous mutation of fibrinogen alpha chain and protein C genes in a Japanese kindred.Afibrinogenaemia usually induces a bleeding tendency during infancy, whereas protein c deficiency increases susceptibility to thrombosis in children or adolescence. Mutations of these genes have been, therefore, established as independent risk factors for coagulation disorders. We describe the homozygous mutation of the fibrinogen alpha chain gene and additional heterozygous mutation of the protein C gene in a male infant who showed prolonged umbilical bleeding after birth. On examination, the plasma fibrinogen was undetectable, and the activity and antigen level of protein C were reduced. The patient showed no fibrinogen Aalpha chain as well as Bbeta and gamma chains by Western blotting. The sequencing analysis showed the homozygous deletion of 1238 bases from intron 3 at position 2008 to intron 4 at position 3245 in the fibrinogen alpha chain gene. Both parents were heterozygous carriers of this mutation. In this patient, an additional mutation was also detected in the protein C gene: the heterozygous deletion of exon 7 at position 6161-6163 or 6164-6166, resulting the deletion of one amino acid (Lys150 or 151). His mother was also a carrier of this mutation. As the simultaneous mutation of the fibrinogen alpha chain and protein C genes has not been previously reported, the influence of the interaction between these two mutations on the clinical manifestations of this patient should be carefully monitored for a long period.- - - - - - - - - - ranking = 0.5keywords = deficiency (Clic here for more details about this article) |
4/16. Molecular characterization of homozygous hereditary factor I deficiency.We have studied the molecular basis of factor I (fI) deficiency in two Brazilian sisters from a consanguineous family. By reverse transcription-polymerase chain reaction we observed that all fI cDNA amplified products from one sister had the same size as those of normal cDNA, however, they were significantly less intense. Sequencing analysis of subcloned cDNA revealed a dinucleotide insertion (AT) between positions 1204 and 1205 in the 11th exon that creates a stop codon 13 bp downstream of the insertion site. Genomic dna sequencing and heteroduplex analysis confirmed that both probands are homozygous for this mutation, whereas their parents are heterozygous. The stop codon and the diminished amounts of fI cDNA could indicate increased fI mRNA instability, perhaps due to a mechanism of nonsense-mediated decay. This hypothesis is consistent with our observation that treatment with the translation inhibitor cycloheximide stabilized fI mRNA expression in proband's fibroblasts.- - - - - - - - - - ranking = 2.5keywords = deficiency (Clic here for more details about this article) |
5/16. Coexistence of congenital afibrinogenemia and protein c deficiency in a patient.A rare association of congenital afibrinogenemia and hereditary protein c deficiency is described in a 37-year-old female who suffered from ischemic necrosis in the left first toe. The diagnosis of afibrinogenemia was assessed by the absence of fibrinogen in clotting and immunological assays. The diagnosis of hereditary heterozygous type I protein c deficiency was based on the evidence of proportional decreases of activity and antigen of plasma protein C in the propositus, her mother, and two maternal aunts.- - - - - - - - - - ranking = 3keywords = deficiency (Clic here for more details about this article) |
6/16. Fibrinogen Mumbai: intracellular retention due to a novel G434D mutation in the Bbeta-chain gene.BACKGROUND AND OBJECTIVES: afibrinogenemia and hypofibrinogenemia are rare inherited coagulation disorders characterized by hemorrhagic manifestations of variable entity and by plasma fibrinogen deficiency. So far, 57 mutations have been associated with these disorders, and 18 of these are missense mutations. The aim of this study was to characterize the molecular mechanism underlying severe hypofibrinogenemia in a proband from india. DESIGN AND methods: The mutational screening was accomplished by dna sequencing of the three fibrinogen genes. The mutant protein was expressed in COS-1 cells, and intracellular and secreted mutant fibrinogen was analyzed by means of pulse-chase experiments. RESULTS: A novel homozygous G-->A transition in exon 8 (nucleotide position 8017) was found in the proband's fibrinogen Bbeta-chain gene. The resulting G434D missense mutation (fibrinogen Mumbai) involves a highly conserved amino acid residue, located in the C-terminal globular D domain. in vitro expression experiments demonstrated intracellular retention of the mutant fibrinogen and marked reduction of its secretion. INTERPRETATION AND CONCLUSIONS: The G434D substitution causes severe hypofibrinogenemia by impairing fibrinogen secretion. Expression data confirm the importance of Bbeta-chain D domain folding in the intracellular processing of fibrinogen.- - - - - - - - - - ranking = 0.5keywords = deficiency (Clic here for more details about this article) |
7/16. Three cases of factor I deficiency: the effect of treatment with plasma.Three patients with congenital factor I deficiency associated with different clinical manifestations are described. Case 1 had one single episode of meningococcal disease, case 2 experienced four episodes of meningococcal disease and several other severe infections, whereas case 3, without known predisposition for infections, died from a subacute immune-complex mediated syndrome, resembling polyarteritis nodosa. family studies in cases 1 and 2 revealed healthy individuals with factor I concentrations below the lower reference limit, indicating heterozygous carriers. The pedigree analyses were consistent with autosomal codominant inheritance. The estimated minimal frequency of the deficient gene was 0.002. pedigree analysis was not performed in case 3 but the father and sister was found to be probable heterozygous carriers. Cases 2 and 3 were treated with infusions of freshly frozen plasma (FFP) (40 and 27 ml/kg bodyweight) during acute illness and the immunochemical complement profile was monitored. Following plasma infusion factor I was cleared from the circulation with a half-life of 29-45 h. The plasma infusions induced generation of C3d and C4d, increase in native factor B and C3 concentrations and disappearance of Ba split products. Native C3 and C4 increased to normal concentrations and remained normal till 16 days after the plasma infusions, whereas native factor B decreased to preinfusion levels 8 days after plasma infusion. It is concluded, that congenital factor I deficiency can present with different clinical manifestations and may be more prevalent than hitherto anticipated. Furthermore, infusion of blood products containing small amounts of functional factor I can partly normalize the complement profile, with a more prolonged effect on C3 and C4 than on factor B metabolism.- - - - - - - - - - ranking = 3keywords = deficiency (Clic here for more details about this article) |
8/16. Liquid extradural hematoma with congenital fibrinogen deficiency. Case report.A case of extradural hematoma in a child with congenital fibrinogen deficiency is reported. Although the hematoma was 3 days old, it was purely liquid.- - - - - - - - - - ranking = 2.5keywords = deficiency (Clic here for more details about this article) |
9/16. Defibrination during warfarin therapy in a man with protein c deficiency.A 57 year old man presented with apparently spontaneous lower extremity deep vein thrombosis and pulmonary embolism. He was treated in conventional fashion with intravenous heparin and oral warfarin. After 4 daily doses of warfarin the prothrombin and proconvertin (P P) time was within therapeutic range, and heparin was stopped. Over the next six hours complete defibrination occurred, associated with severe bleeding complications. Functional protein C measured after normalization of routine coagulation tests averaged 40% of normal, and was only 3.5% of normal immediately prior to the episode of defibrination. We conclude that the very low functional protein C levels seen immediately prior to defibrination were caused by a combination of pre-existent protein c deficiency and warfarin therapy, and directly predisposed to defibrination once heparin was stopped, despite "therapeutic" warfarin anticoagulation. Exacerbation of intravascular coagulation should be considered a potential prothrombotic effect of warfarin therapy in protein C deficient individuals.- - - - - - - - - - ranking = 2.5keywords = deficiency (Clic here for more details about this article) |
10/16. Congenital afibrinogenemia and recurrent early abortion: a case report.The role of the fibrinogen molecule in the maintenance of normal pregnancy is not yet well understood; however, several cases have been previously reported in which failure to complete normal pregnancy was associated with either hypofibrinogenemia, dysfibrinogenemia, or deficiency in factor xiii (fibrin-stabilizing factor) which is important for the crosslinking of the fibrin. A case of congenital afibrinogenemia is described. The patient, a 22-yr-old woman, who suffered from a moderate hemorrhagic tendency associated with very low (less than 10 mg/dl) plasma fibrinogen levels, had three consecutive spontaneous abortions. In view of the previous cases reported, the question is raised whether patients with low or abnormal fibrinogen should be treated with plasma transfusions in order to maintain a normal pregnancy.- - - - - - - - - - ranking = 0.5keywords = deficiency (Clic here for more details about this article) |
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