1/8. A G-to-A mutation in IVS-3 of the human gamma fibrinogen gene causing afibrinogenemia due to abnormal rna splicing.Congenital afibrinogenemia is a rare autosomal recessive disorder characterized by a hemorrhagic diathesis of variable severity. Although more than 100 families with this disorder have been described, genetic defects have been characterized in few cases. An investigation of a young propositus, offspring of a consanguineous marriage, with undetectable levels of functional and quantitative fibrinogen, was conducted. sequence analysis of the fibrinogen genes showed a homozygous G-to-A mutation at the fifth nucleotide (nt 2395) of the third intervening sequence (IVS) of the gamma-chain gene. Her first-degree relatives, who had approximately half the normal fibrinogen values and showed concordance between functional and immunologic levels, were heterozygtes. The G-to-A change predicts the disappearance of a donor splice site. After transfection with a construct, containing either the wild-type or the mutated sequence, cells with the mutant construct showed an aberrant messenger RNA (mRNA), consistent with skipping of exon 3, but not the expected mRNA. Sequencing of the abnormal mRNA showed the complete absence of exon 3. Skipping of exon 3 predicts the deletion of amino acid sequence from residue 16 to residue 75 and shifting of reading frame at amino acid 76 with a premature stop codon within exon 4 at position 77. Thus, the truncated gamma-chain gene product would not interact with other chains to form the mature fibrinogen molecule. The current findings show that mutations within highly conserved IVS regions of fibrinogen genes could affect the efficiency of normal splicing, giving rise to congenital afibrinogenemia.- - - - - - - - - - ranking = 1keywords = diathesis (Clic here for more details about this article) |
2/8. Embolized ischemic lesions of toes in an afibrinogenemic patient: possible relevance to in vivo circulating thrombin.Fibrinogen plays a complex role in hemostasis, thrombosis, and vascular disease. Hyperfibrinogenemia is an independent vascular risk factor and dysfibrinogenemia can provoke thrombosis. afibrinogenemia is usually responsible for hemorrhagic diathesis, and unexpected ischemic lesions are intriguing. We report the case of an afibrinogenemic patient, who at the age of 30 developed ischemic lesions of the feet related to severe stenosis of the iliac and hypogastric arteries. The biopsy of the iliac artery lesion showed an intense myointimal hyperplasia. We performed standard hemostatic analysis and analyzed the activation markers of platelets and coagulation factors and the kinetics of thrombin generation in the patient and in normal control plasmas treated or not with reptilase. Occlusive arterial lesions were attributed to a disruptive hematoma penetrating the vascular lumen. Thrombin concentration after calcium addition increase markedly in the afibrinogenemic patient and in defibrinated normal plasma, as compared to untreated normal plasma. Thrombin-antithrombin complexes (T-AT) were markedly enhanced while F1 2 prothrombin fragments stayed in the normal range. These results suggested activation of coagulation and in vivo circulating thrombin. Thrombin activates the platelets that secrete growth factors for smooth muscle cells and generate the intimal hyperplasia. Recurrent hemorrhage within the vessel wall might induce injury and local thrombin generation. Thrombin not trapped by the clot is available for platelet activation and smooth muscle cell migration and proliferation. The absence of a protective fibrin cap on the intima might account for intima vulnerability and embolization. afibrinogenemia appears in this paradoxical situation as a vascular risk factor.- - - - - - - - - - ranking = 1keywords = diathesis (Clic here for more details about this article) |
3/8. Acquired dysfibrinogenemia secondary to mithramycin toxicity.A 58-year-old black woman with IgD multiple myeloma developed a hemorrhagic diathesis within 48 hours after receiving mithramycin (20 micrograms/kg/day) for therapy of hypercalcemia. Her coagulation studies were characterized by prolonged prothrombin, partial thromboplastin, thrombin, and reptilase clotting times. Her plasma and partially purified fibrinogen were inhibitory to the clotting of normal plasma and fibrinogen. The patient's isolated fibrinogen showed a normal rate of fibrinopeptide release, but her fibrin monomer aggregation was markedly abnormal. These studies document the development of a dysfibrinogenemia secondary to mithramycin toxicity.- - - - - - - - - - ranking = 1keywords = diathesis (Clic here for more details about this article) |
4/8. Fibrinogen Vicenza and Genova II: two new cases of congenital dysfibrinogenemia with isolated defect of fibrin monomer polymerization and inhibitory activity on normal coagulation.Two new cases of congenital dysfibrinogenemia are presented in which defective fibrin monomer polymerization and inhibitory activity on normal coagulation were observed. They have been tentatively called fibrinogen Vicenza and Genova II. The first was discovered in a family with mild bleeding diathesis, the second in an asymptomatic family. In almost all reported cases of fibrinogens with defective fibrin monomer polymerization, additional functional or structural defects have been detected. In our cases, on the contrary, detailed investigations failed to show any other abnormality. Fibrinogen Genova II is apparently identical to fibrinogen baltimore IV, whereas fibrinogen Vicenza is similar to fibrinogen Troyes and Genova I, but also exerts an evident inhibitory activity on normal coagulation and differs from fibrinogen Genova II and baltimore IV showing a different kinetic pattern of fibrin monomer polymerization.- - - - - - - - - - ranking = 1keywords = diathesis (Clic here for more details about this article) |
5/8. Fibrinogen giessen I: a congenital homozygously expressed dysfibrinogenemia with A alpha 16 ArgHis substitution. Clinical reports are published for only two patients with homozygously expressed congenital dysfibrinogenemia. The patients, both of whom have a bleeding diathesis, have amino acid substitutions in the fibrinogen molecule at A alpha 16 Arg Cys and A alpha 19 Arg Ser, respectively. We report that a third patient with dysfibrinogenemia (fibrinogen Giessen I) is homozygous for A alpha 16 Arg His. Although this patient has had excessive postpartum bleeding, she has had normal hemostasis throughout several minor surgical procedures and hysterectomy. Elucidation of the amino acid alterations in patients with dysfibrinogenemia may expand our understanding of structural determinants of fibrinogen that are critical to its function in vivo.- - - - - - - - - - ranking = 1keywords = diathesis (Clic here for more details about this article) |
6/8. Haemorrhagic diathesis as a possible early sign of hereditary fructose intolerance.An infant girl three weeks of age with the leading symptom of skin haemorrhages is presented. On further investigation, the signs of severe hepatic damage with hypofibrinogenaemia and prothrombin complex impairment, and renal tubular dysfunction were disclosed. All these pathological symptoms, which were reversed on fructose free diet, were caused by hereditary fructose intolerance.- - - - - - - - - - ranking = 4keywords = diathesis (Clic here for more details about this article) |
7/8. Fibrinogen Guarenas I: partial characterization of a new dysfibrinogenemia with an altered rate of fibrinopeptide release and an impaired polymerization.A congenitally abnormal fibrinogen was isolated from the blood of a young woman with a severe bleeding diathesis. Coagulation tests showed a prolonged Thrombin and Reptilase time partially corrected by Ca2 . polymerization of thrombin induced preformed fibrin monomers was severely impaired. Thrombin caused the release of fibrinopeptides with normal retention times on HPLC. However, the rate of release was abnormally slow and the total amount of fibrinopeptide a (FpA) released reached only approximately 50% of the theoretical maximum. The rate and quantity of FpA release was normal when Reptilase was used. Transmission Electron microscopy (TEM) of Thrombin induced clots showed an altered clot structure characterized by a reduced mean fiber diameter. The mother has a polymerization defect similar to the propositus, her fibrinopeptide release is unaffected however. The father has a minor fibrinopeptide release defect suggesting the presence of two populations of fibrinogen. This study supports the idea that the fibrinogen isolated from the propositus has two defects inherited as separate genetic traits. This fibrinogen has been named Fibrinogen Guarenas I.- - - - - - - - - - ranking = 1keywords = diathesis (Clic here for more details about this article) |
8/8. Severe coagulopathy after a bite of a green bush viper (Atheris squamiger): case report and biochemical analysis of the venom.A 34 year old male bitten by an adult Atheris squamiger snake developed symptoms of nausea, vomiting, diarrhea which were followed by drowsiness and impaired breathing. Local hemorrhage, edema and pain at the bite-site occurred, but no systemic bleeding or hemorrhagic diathesis developed. All clinical and laboratory parameters were in the normal range except for afibrinogenemia, thrombocytopenia and slight proteinuria. Replacement therapy (fibrinogen and platelet concentrates) and treatment of shock stabilized the patient within 2d and coagulation returned to normal. Atheris squamiger venom was subjected to biochemical and biological analysis. The LD50 of the venom was 5 mg/kg (mice, s.c.). It produced local hemorrhage corresponding to about 25% of the activity of puff adder venom (Bitis arietans). in vitro the venom had a fibrinogen-converting activity, it did not activate purified prothrombin but very likely contained a F V and Ca2 -dependent prothrombin activator. The venom exhibited strong platelet-aggregating activity, which was not inhibited by protease inhibitors and by EDTA or EGTA. The venom also aggregated acetylsalicylic acid treated platelets indicating, that the arachidonic acid pathway was not essential for activation. Rat serum rapidly inhibited the platelet-aggregating activity of the venom; human serum, however, had only a partial inhibitory effect. Preliminary experiments showed that platelet-aggregating activity may be separated from fibrinogen-converting activity by anion-exchange chromatography.- - - - - - - - - - ranking = 1keywords = diathesis (Clic here for more details about this article) |