Hemostatic enzyme generation in the blood of patients with hereditary protein C deficiency. (41/74)

The presence of hereditary protein C deficiency has been shown to predispose patients to the development of venous thrombosis. We used radioimmunoassays for the protein C activation peptide (PCP) and the prothrombin fragment F1 + 2 to quantitate the extent of in vivo activation of protein C by thrombin-thrombomodulin and prothrombin by factor Xa, respectively, in the blood of individuals with this clinical disorder. A total of 46 protein C deficient subjects from 18 kindreds were studied. In 23 nonanticoagulated patients with an isolated deficiency of protein C, the mean level of PCP was substantially reduced while the mean concentration of F1 + 2 was significantly elevated as compared with normal controls (1.10 pmol/L v 1.78 pmol/L, P less than .0005 and 2.54 nmol/L v 1.51 nmol/L, P less than .0005, respectively). The metabolic behavior of 131I-F1 + 2 was found to be similar in protein C deficient patients and normal individuals. However, we were unable to establish a significant correlation between decreased PCP levels and increased F1 + 2 measurements in these 23 patients. This study demonstrates that heterozygous protein C deficient individuals with equivalent plasma levels of the zymogen may have markedly different biochemical profiles when assay techniques are used that quantitate the in vivo activity of the coagulation system. Six individuals from three pedigrees were identified as having combined deficiencies of protein C and either antithrombin III or protein S; the genetic basis for the combined deficiency state was determined in two of the kindreds. Finally we observed that hemostatic system activity as measured by the PCP and F1 + 2 assays is markedly suppressed in protein C deficient patients who are chronically anticoagulated with coumarin derivatives.  (+info)

Hereditary thrombosis in a Utah kindred is caused by a dysfunctional antithrombin III gene. (42/74)

Maximum likelihood analysis of linkage between antithrombin III (ATIII) DNA polymorphisms and ATIII deficiency in a large Utah kindred suggests that thrombotic disease in this family is caused by a dysfunctional ATIII gene. ATIII-deficient family members were identified on the basis of: (1) reduced anticoagulant activity and (2) the presence of an electrophoretically abnormal inhibitor molecule in their plasmas. Affected individuals have two copies of the ATIII structural gene, and both alleles appear normal at the resolution of whole genome Southern blotting. However, family studies revealed statistically significant cosegregation of ATIII-deficiency trait and a particular ATIII DNA polymorphism haplotype (lod = 3.35; theta = 0.0); this result is consistent with the presence of a dysfunctional ATIII gene on a chromosome of the +, S haplotype.  (+info)

Evidence linking familial thrombosis with a defective antithrombin III gene in two British kindreds. (43/74)

Using DNA probes in a structural study of the antithrombin III gene locus we found no evidence of gene deletion in two British kindreds with inherited antithrombin III deficiency. However, linkage analysis between a common DNA polymorphism and the antithrombin III deficiency trait showed that the defect lies at or close to the antithrombin III structural gene. The lod score for linkage within the larger Scottish kindred was 3.1 (theta = 0). These results are consistent with previously published data suggesting that mutation of the antithrombin III structural gene is the cause of inherited antithrombin III deficiency in some families.  (+info)

Use of synthetic oligonucleotides in the characterization of antithrombin III Northwick Park (393 CGT----TGT) and antithrombin III Glasgow (393 CGT----CAT). (44/74)

Antithrombin III (ATIII) Northwick Park is caused by a single amino acid substitution, Arg 393---Cys and antithrombin III Glasgow is caused by Arg 393----His. Examination of the genetic code and the sequence of normal antithrombin III revealed that these amino acid substitutions could arise from the substitution of either two nucleotides or a single nucleotide at codon 393 of the antithrombin III gene. In two families, detection of the ATIII variants by genetic linkage analysis was not possible owing to lack of informative RFLP markers. Consequently, we synthesized two 22-base-long oligonucleotides specific for the single-base substitutions in the region of codon 393 and demonstrated by oligonucleotide hybridization that the molecular defect of ATIII Northwick Park is caused by the CGT----TGT mutation at codon 393 and that ATIII Glasgow is caused by the CGT----CAT mutation at codon 393. These oligonucleotide probes should prove useful as an alternative method for early detection of the ATIII variants.  (+info)

Abnormal antithrombin III with defective serine protease binding (antithrombin III "Denver"). (45/74)

A hereditary (three family members) deficiency of antithrombin III (AT-III) in which AT-III antigen (AT-III ag) is normal in spite of low heparin cofactor and antithrombin activity is described. Plasma levels were: AT-III ag, 0.92-0.96 U/ml; AT-III heparin cofactor activity, 0.54-0.62 U/ml; progressive antithrombin activity index, 0.13-0.18; anti-Xa activity, 0.50-0.56 U/ml. Plasma crossed immunoelectrophoresis (CIE) patterns performed with and without added heparin were normal, but serum CIE revealed a decreased complex peak. Purification of the patient's plasma AT-III by heparin-sepharose affinity chromatography showed a normal protein recovery and elution profile, but the purified AT-III fraction showed only 50% of the normal progressive thrombin neutralization and anti-Xa activity. When thrombin-antithrombin (TAT) complexes were formed by incubating with excess thrombin, SDS-polyacrylamide gel electrophoresis (PAGE) analysis revealed that half the patient AT-III formed TAT complexes while the remainder migrated as free AT-III. All the control AT-III formed TAT complexes. The patient's nonreacting AT-III (AT-III "Denver"), isolated by affinity chromatography, showed CIE and SDS-PAGE migration patterns characteristic of normal AT-III but failed to bind thrombin or Xa. Calculations from turnover studies in one patient and normal subjects with autologous 131I-AT-III suggested that AT-III "Denver" is removed from the plasma slightly more rapidly than normal. These studies indicate that the patients' variant AT-III molecule was characterized by normal heparin interaction but defective binding and inhibition of thrombin and Xa. These characteristics allow isolation of the nonreactive variant molecule by heparin-sepharose affinity chromatography.  (+info)

Mesenteric venous thrombosis and antithrombin III deficiency. (46/74)

Of the 123 patients with acute mesenteric infarction treated over the past 12 years, 16 (13%) had mesenteric venous thrombosis. Eight of the patients with mesenteric venous thrombosis survived the initial episode; two have since died. The remaining six patients were studied for evidence of haemostatic deficiencies or abnormalities. Antithrombin III deficiency, which is known to be associated with recurrent venous thrombosis, was found in three patients. It is recommended that all patients with mesenteric venous thrombosis should be screened for antithrombin III deficiency as treatment with coumarin anticoagulants may be indicated, providing effective prophylaxis against further thrombotic episodes.  (+info)

Molecular genetic survey of 16 kindreds with hereditary antithrombin III deficiency. (47/74)

Molecular genetic techniques were utilized to examine antithrombin III (ATIII) gene status in 16 independently ascertained kindreds with hereditary ATIII deficiency. In one of these families antithrombin III deficiency is caused by hemizygosity of the ATIII locus. In the remaining 15 kindreds, two copies of the ATIII gene are present and appear to be grossly normal at the level of whole genome Southern blotting, suggesting that small deletions, insertions or limited nucleotide substitution(s) in the antithrombin III gene, or "trans-acting" defects at other loci involved in the processing, modification, and secretion of biologically active ATIII are responsible for the observed anticoagulant disorders.  (+info)

Purified radiolabeled antithrombin III metabolism in three families with hereditary AT III deficiency: application of a three-compartment model. (48/74)

Purified human radioiodinated antithrombin III (125I-AT III) was used to study its metabolism in six members from three different families with a known hereditary AT III deficiency. Six healthy volunteers served as a control group. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and crossed immunoelectrophoresis (CIE) showed the purified AT III to be homogeneous. Amino acid analysis of the protein revealed a composition identical to a highly purified internal standard. The specific activity was 5.6 U/mg. Analysis of plasma radioactivity data was performed, using a three-compartment model. Neither plasma disappearance half-times nor fractional catabolic rate constants differed significantly between patients and control subjects. The mean absolute catabolic rate in the patient group was significantly lower than that of the control group at 2.57 +/- 0.44 and 4.46 +/- 0.80 mg/kg/day, respectively. In addition, the mean patient alpha 1-phase, flux ratio (k1,2 and k2,1) of the second compartment alpha 2-phase and influx (k3,1) of the third compartment were significantly reduced as compared with control values. It has been tentatively concluded that the observed reduction in the second compartment may be caused by a decrease in endothelial cell surface binding.  (+info)