Subject(s)
Factor VII Deficiency/genetics , Factor VII , Factor XI Deficiency/genetics , Factor XI , Adult , Blood Coagulation Tests , DNA Mutational Analysis , Enzyme-Linked Immunosorbent Assay , Factor VII Deficiency/complications , Factor XI Deficiency/complications , Family Health , Female , Humans , Male , Mutation , PregnancyABSTRACT
A fibrinogen variant was suspected based on the results of routine coagulation tests in a 2-year-old asymptomatic child. Coagulation studies showed marked prolongation of both the thrombin and reptilase times, and discrepancy was noted between the level of plasma fibrinogen as measured by a kinetic versus immunological determination. Family studies revealed that the father beared the same abnormality. Studies of purified fibrinogen revealed an impaired release of both fibrinopeptides by thrombin. Fibrin monomer polymerization and fibrin stabilization were normal. DNA sequencing revealed a heterozygous G --> T point mutation in exon 2 of the gene coding for the Aalpha chain, which substituted a Gly for Val at position 12. Although the mutation is the same as in fibrinogen Rouen, fibrinogen Saint-Germain I shows a different fibrinopeptide release pattern and a mild factor V deficiency.
Subject(s)
Coagulation Protein Disorders/diagnosis , Fibrinogens, Abnormal/genetics , Point Mutation , Amino Acid Substitution , Child, Preschool , Coagulation Protein Disorders/genetics , DNA Mutational Analysis , Diagnosis, Differential , Factor V Deficiency , Family Health , Female , Fibrinopeptide A/analysis , Fibrinopeptide B/analysis , Genetic Variation , Heterozygote , HumansABSTRACT
In order to identify unknown mutations, the FAMA method was used to rapidly screen the fibrinogen chain genes in individuals with dysfibrinogenemias. Chemical cleavage at mismatches on heteroduplexes DNA end-labeled with strand-specific fluorescent dyes reliably detects sequence changes in DNA fragments of up to 1.5 kb and locates them precisely. This method was successfully used for the detection of three new dysfibrinogenemias: Poissy III, Tahiti (heterozygous Aalpha Arg16His) and Saint-Germain I (heterozygous AalphaGly12Val). The mutations were confirmed by dideoxy sequencing.
Subject(s)
Coagulation Protein Disorders/genetics , Fibrinogens, Abnormal/analysis , Adult , Amino Acid Substitution , Child, Preschool , Coagulation Protein Disorders/diagnosis , DNA Mutational Analysis/methods , Female , Fibrinogens, Abnormal/chemistry , Fibrinogens, Abnormal/genetics , Heterozygote , Humans , Mutation , Polymorphism, Single-Stranded Conformational , Sequence Analysis, DNAABSTRACT
A fibrinogen variant was identified in a patient with disseminated intravascular coagulation and in one member of her family. Coagulation studies showed marked prolongation of both the thrombin and reptilase times and discrepancy was noted between the levels of plasma fibrinogen, determined by a kinetic vs immunological determination or light scattering assay. Studies on purified fibrinogen revealed an impaired release of fibrinopeptides by thrombin. DNA sequencing revealed a heterozygous A to G point mutation in exon 2 of the A alpha chain, which substituted Arg for His at position 16. This mutation creates a Nla III cleavage site which was used to confirm the mutation.
Subject(s)
Disseminated Intravascular Coagulation/genetics , Fibrinogen/genetics , Point Mutation , Adult , Arginine/genetics , Female , Histidine/genetics , Humans , Pregnancy , Sequence Analysis, DNASubject(s)
Polymerase Chain Reaction/methods , Prothrombin/genetics , Adult , Female , Genetic Carrier Screening , Humans , Male , Middle Aged , MutationABSTRACT
Activated protein C resistance ratio (APC-Rr), factor VIIIC (FVIIIC) and plasma fibrinogen levels were studied in patients with inflammatory disease. The patient mean APC-Rr was significantly lower than in the control group. This decreased ratio in inflammatory diseases appeared to be connected with increased FVIIIC. Moreover, supplementation of plasmas with purified factor VIII decreased the APC-Rr in plasma from both groups, and suppressed the difference between groups. These data suggest that factor VIIIa and factor Va compete for protein C-catalysed cleavage. Ratios were identical in both groups when FVIIIC level was lowered by dilution in factor V deficient plasma.
Subject(s)
Factor VIII/metabolism , Inflammation/metabolism , Protein C/metabolism , Binding, Competitive , Blood Component Transfusion , Factor VIII/administration & dosage , Factor VIIIa/metabolism , Factor Va/metabolism , Female , Fibrinogen/metabolism , Humans , MaleABSTRACT
We studied activated protein C sensitivity ratio (APC-SR), factors V and VIII activity and von Willebrand antigen in control women, women using oral contraceptives, and pregnant women at delivery. The mean APC-SR of 2.4 in pregnant women was significantly lower than the mean APC-SR value of 3.5 for both the other groups and 45% of pregnant women had a ratio below the 5th percentile of the control group. None of them carried the R506-->Q mutation. This decreased ratio at delivery appeared to be connected, at least in part, with increased VIII activity. Thus, APC-SR at delivery should not be used to detect APC resistance.
