Hereditary antithrombin III deficiency: Effect of antithrombin III deficiency on platelet function

Antithrombin III (AT III) is the main physiologic inhibitor of thrombin, and activated factors X and IX as well. Normal levels of AT III appear to be necessary to maintain blood fluidity and to prevent thrombosis. Four families with AT III deficiency and recurrent venous thromboembolism have been reported on. We present an additional family with AT III deficiency and a high incidence of thromboembolism. AT III levels were determined by both a functional and an immunologic assay. Results of platelet function tests, not previously reported in persons with AT III deficiency, were found to be normal. Following gel filtration, the platelets were very sensitive to thrombin. Thrombin-induced platelet aggregation appears to be dependent on a balance between the amount of thrombin and AT III present.     

Familial thrombosis due to antithrombin III deficiency in a Greek family.

A Greek family with hereditary antithrombin III (AT III) deficiency associated with venous thrombosis is reported. 5 members of the family were affected. In these patients, AT III and heparin cofactor activities were decreased. Immunoreactive AT III showed a positive correlation to both AT III and heparin cofactor activities. alpha2-Macroglobulin and alpha1-antitrypsin were normal. The pattern of inheritance of the defect is autosomal dominant.     

Antithrombin III Glasgow: a variant with increased heparin affinity and reduced ability to inactivate thrombin, associated with familial thrombosis

A functional antithrombin III (AT III) deficiency has been identified in two generations of a family with a high incidence of thrombosis. The deficiency presented as approximately 50% reduction in heparin cofactor activity compared to its antigen concentration. No abnormality was detected by crossed immunoelectrophoresis in the presence or absence of heparin. Plasma from the propositus was precipitated with dextran sulphate, applied to heparin-Sepharose and the AT III stepwise eluted with NaCl. The AT III had a reduced ability to inactivate thrombin, when this was monitored by substrate hydrolysis or by SDS polyacrylamide gel electrophoresis. Its mobility was normal by the latter technique using 10-20% gradient gels under reducing and non-reducing conditions. AT III from the patient was reapplied to heparin-Sepharose and eluted with a NaCl gradient. An active pool eluted in the same NaCl concentration range used to purify normal AT III, while predominantly inactive AT III eluted at higher NaCl concentrations. It is concluded that this variant, designated AT III Glasgow, has increased affinity for heparin but reduced ability to inactivate thrombin.     

Clinical and genetic aspects of antithrombin III deficiency and abnormal antithrombin III

Antithrombin III (AT III) has been confirmed to play an important role as a serine protease inhibitor in the mechanism of blood coagulation, and its deficiency or abnormality is found to cause thromboembolic disorders by reducing the anticoagulant activity. In this paper AT III gene of patient with congenital AT III deficiency, which was suggested to have qualitative abnormality by isoelectric focusing, was investigated. Analysis of the genomic structure by Southern blot hybridization with a cDNA probe (pAT6) revealed no detectable changes indicating any deletions, rearrangements and translocations. Therefore, we focused to analyze the sequence of exon 6 of AT III gene by polymerase chain reaction (PCR) methods followed by direct sequencing analysis. Nucleotide sequencing of exon 6 of AT III gene showed a G to T transitional mutation resulting in the conversion of arginine-406 to methionine coexisted with normal allele which encodes arginine. The mutation is located near the reactive center of AT III molecule, which region has been proved to be highly conserved during the evolution of serine protease inhibitor (serpin) family. From these results, it is concluded that the new type of mutation at amino acid site 407, which is similar to AT III Utah, is important for maintaining the structural and biological function of this inhibitor.     

A comparison of antithrombin III procedures

Summary Antithrombin III (AT III) is the most potent physiologic inactivator of thrombin and other serine proteases in the blood clotting mechanism. Hereditary deficiency of this protein is associated with recurrent deep-vein thrombosis that begins in late adolescence. Untreated, this disease may lead to early death from recurrent and massive pulmonary emboli. Attempts to identify groups of patients who are the most likely to develop thromboembolic disease because of an acquired deficiency of AT III have been frustrated by the lack of standardization of the assays and the inability to compare results of the different AT III assays. The functional assays and immunoelectrophoretic determinations do not measure the same component. In order to compare the ability of current AT III procedures to determine levels of AT III in various disease states, we used immunoelectrophoretic, chromogenic, and clottable assays to measure the AT III of patients with congenital AT III deficiency and of patients with possible acquired AT III deficiency.     

Clinical Use of Antithrombin HI Concentrates

The biochemical and biological properties of antithrombin III (AT III) and the clinical consequences of a deficiency of this inhibitor are described. Therapy with concentrates of purified AT III has been carried out for about 10 years and the present experience is reviewed. In a relatively small number of patients with congenital AT III deficiency it is necessary, under certain condition to substitute AT III. A considerably more frequent use of AT III concentrates has been made in acquired AT III deficiency, especially in shock and diffuse intravascular coagulation (DIC). This therapy was shown to be promising since the duration of DIC could be considerably shortened and the frequency of fatal events could be significantly diminished. No undesirable side effects of substitution with virus-sterilized AT III concentrates have been hitherto observed.     

A case of congenital antithrombin II deficiency with pulmonary infarction

A 48-year-old woman was admitted because of increased bloody sputum. Since she had had a history of repeated thrombotic episodes including venous thrombosis in the lower limbs (21 year old) and pulmonary emboli developing into pulmonary infarction (41 years old), the patient was treated with anti-coagulant therapy using Warfarin for 7 years. Warfarin was discontinued after admission and heparin was administered instead at a relatively low dose of 5,000 units daily, resulting in a considerable diminution of hemoptysis. Unfortunately however, it caused a relapse of active thrombosis associated not only with a significant increase of the product of fibrinolysis (FDP), LDH and GOT but with a concomitant decrease of the platelet count. Hematological examinations concerning coagulation and fibrinolysis remained within a normal range except for the serum concentration of antithrombin III (AT III) and its functional property with regard to the heparin cofactor, which were 8.8 mg/dl and 48%, respectively. Since the findings were consistent with congenital deficiency of AT III, some members of her family were also examined. The concentration of AT III and its activity in the patient's son and her daughter deteriorated in a similar manner, indicating that this was a definite case of congenital deficiency of AT III. The clinical manifestations of 87 cases with congenital AT III deficiency, belonging to 24 families reported in Japan were reviewed.     

Influence of demographic factors on antithrombin III activity in a healthy population

Summary. Antithrombin III (AT III) activity has been measured in 9669 healthy blood donors (5525 male and 4144 female). The distribution of AT III is approximately 'normal' with mean 105·6 iu/dl and standard deviation 11·2; however, definite age and sex related variations are evident. Pre-menopausal females have lower mean AT III compared to their male contemporaries who have remarkably stable mean AT III until 45 years, after which there is a gradual decline. In contrast, post-menopausal females have higher mean AT III than both males of the same age and younger pre-menopausal females. Concurrent hormone replacement therapy inhibits this rise. The use of hormonal preparations is associated with a 4 iu/dl reduction of mean AT III in younger females but not in those over 30 years. Smoking may result in a mild increase in AT III of doubtful clinical significance. On-going genetic and family studies are expected to predict a prevalence rate of congenital AT III deficiency in excess of the previously reported figure of 0·02%. The authors consider these observed variations as minor and recommend the use of a single reference range for AT III activity, but that particular care be taken when interpreting results in pill-taking females and the elderly.     

The antithrombin III content of cryoprecipitate prepared from blood collected with and without heparin

Antithrombin III (AT III) is a plasma protein which acts as the principal inhibitor of thrombin and is a major modulator of intravascular coagulation. Hereditary deficiency of AT III leads to recurrent episodes of thromboembolism. Acquired deficiency of AT III occurs in persons with a variety of conditions, including severe liver disease and disseminated intravascular coagulation. Replacement of AT III may be important in some deficient persons. To determine if cryoprecipitate is a useful source of AT III, we measured the AT III content of cryoprecipitate prepared from citrate phosphate dextrose blood using coagulation and fluorogenic assays and immunoassays. Using the fluorogenic assay, we also determined the effect of adding heparin to blood on the cryoprecipitation of AT III. Functional and antigenic AT III levels were similar to those of normal plasma in all citrate phosphate dextrose blood units tested, indicating that AT III is not concentrated in cryoprecipitate. Heparin had no effect on the cryoprecipitation of AT III.     

Acquired antithrombin III deficiency]

Acquired antithrombin III (AT III) deficiency is based on either decreased activity or synthesis, increased loss or increased consumption. The activity of AT III is decreased in metabolic acidosis, hyperlipoproteinemias and by lipid peroxides. Chronic liver diseases especially liver cirrhosis are associated with very low levels of AT III due to insufficient hepatic synthesis, reduced transcapillary flux ratios, diffuse intravascular coagulation and loss in the ascites. Gastrointestinal loss of AT III may occur in patients with active inflammatory bowel diseases. AT III deficiency is observed in nephrotic syndrome when urinary loss of protein exceeds 5 g/d. During hemodialysis we have not found low AT III levels. Disseminated intravascular coagulation is characterized by activation of the coagulation system and increased consumption of AT III. AT III complexes with activated coagulation factors are subsequently cleared by the reticuloendothelial system.     

Antithrombin III metabolism in two patients with a nephrotic syndrome caused by minimal chain nephritis and primary amyloidosis

The metabolism and urinary excretion of 125I antithrombin III (AT III) was investigated in 2 patients with a nephrotic syndrome caused by minimal chain nephritis and primary amyloidosis, and acquired deficiency of AT III. Increased AT III catabolism was observed in both patients, even after correction for urinary protein loss. Increased AT III catabolism was due to increased influx from the extra- to the intravascular compartment in 1 patient, and to an increased fractional catabolic rate in the other patient who developed later a pulmonary embolism. Analysis of urine samples revealed biologically inactive whole AT III molecules and biologically as well as antigenically inactive fragments, respectively, whereas daily plasma gel filtration showed intact radioactive AT III. These observations reject the hypothesis that AT III deficiency in nephrotic patients is only due to urinary loss of AT III.     

Hereditary deficiency of antithrombin III, protein C and protein S: prevalence in patients with a history of venous thrombosis and criteria for rational patient screening.

Data in the literature on the prevalence of hereditary deficiency of the natural coagulation inhibitors are conflicting. We conducted a prospective study on 680 consecutive patients with a history of venous thrombosis to determine the prevalence of hereditary deficiency of antithrombin III (AT III), protein C(PC) and protein S(PS) and to establish selection criteria for rational patient screening. The mean age of the patients at investigation was 44.3 +/- 15.4 years, while that at the first thrombotic event was 38.5 +/- 14.8 years. The total prevalence of inhibitor deficiency states was 48/680 (7.1%). 19/680 patients (2.8%) had AT III-deficiency, 17 (2.5%) PC-deficiency, nine (1.3%) PS-deficiency and three (0.4%) a combined deficiency. In 37/48 deficient patients family studies were performed and the hereditary nature was established in 19 cases (2.8% of total patient population, six with AT III-deficiency, eight with PC-deficiency, four with PS-deficiency and one with a combined deficiency). Family studies in these 19 patients revealed 46 additional individual patients with a hereditary deficiency state. A positive family history was found in 15/19 (79%) with a proven hereditary deficiency state, in 153/619 (25%) of non-deficient patients and in 11/29 (38%) of deficient patients without established hereditary nature. The mean age at the first thrombotic event was significantly lower in patients with a hereditary deficiency state (26.8 years) compared with the other two groups (39.0 and 39.7 years, respectively). In all patients with a hereditary deficiency the first thrombotic event occurred before the age of 45 years.(ABSTRACT TRUNCATED AT 250 WORDS)     

An abnormal antithrombin III (AT III) with low heparin affinity: AT III Clichy

We have identified an inherited qualitative deficiency of antithrombin III (AT III) in a family with apparently no increased incidence of venous thrombosis. Plasma antithrombin and anti-Xa activities were normal, but the interaction with heparin, heparan sulphate and low molecular weight heparin was uniformly decreased. An immunoblotting technique performed in plasma showed normal complex formation with thrombin. By using heparin-Sepharose affinity chromatography and crossed immunoelectrophoresis, the variant could be separated: at least two fractions of low affinity AT III were obtained. A minor one had no antiprotease activity; the other one was further purified to homogeneity and found to have normal specific activity in absence of heparin and a 50% decreased activity in presence of heparin. We propose to call this new variant AT III Clichy.     

Antithrombin-Gly 424 Arg: a novel point mutation responsible for type 1 antithrombin deficiency and neonatal thrombosis

Inherited type 1 antithrombin (AT) III deficiency is characterized by a decrease of immunoreactive and functional protein levels to about 50%. The disorder is associated with a significantly increased risk of thromboembolism. We have investigated the molecular basis of type 1 AT deficiency in a Belgian family. The diagnosis of the disease was primarily made in a newborn girl with unusually severe thrombotic complications. Using the polymerase chain reaction and single-strand conformation polymorphism analysis, followed by direct sequencing of AT gene fragments, we identified a novel point mutation in exon 6. We detected a G to C substitution in the first position of codon 424 leading to a glycine to arginine substitution. The modification at this highly conserved position in the serine protease inhibitor gene family probably leads to an unstable mutant-gene product. The mutation creates a unique restriction site for the enzyme Hha I in exon 6. This change permitted a rapid and accurate screening of the kindred with identification of the molecular defect in five other family members.     

Anti-coagulant therapy--antithrombin III

Biological properties and the efficacy of AT III concentrate for the treatment of thromboembolic disorders were evaluated in the patients with AT III deficiency. Commercially available AT III concentrates showed heterogeneity on agarose gel isoelectric focusing, however, they inhibited thrombin in the same manner. At III concentrates were infused to 11 patients with congenital AT III deficiency (4 with thrombosis). Pharmacokinetic parameters of infused AT III were calculated as follows; half time 61.1 +/- 23.0 hr. (58.4 +/- 22.6 hr. in the cases with thrombosis), max increase rate 1.01 +/- 0.3%/U/kg and recovery rate 95.4 +/- 33.3%. Simulation curves adjusted to the multiple administration were correlated well with the actually determined values in the patients and steady state concentration of AT III was achieved by the administration of this concentrate in 12 or 24 hour intervals. Clinically, substitution with AT III concentrate was proved to be effective for the treatment of thromboembolism in these patients. 16 patients with disseminated intravascular coagulation were treated with heparin (6,000 U/day) followed by AT III concentrate (1,500 U/day) administration. Clinical symptoms and laboratory findings were improved in 11 patients. From these results substitution with AT III concentrate was suggested to be beneficial for the prevention or the treatment of thromboembolic disorders in the patients with AT III deficiency.     

Prophylaxis of thrombosis in a pregnant woman with congenital antithrombin III deficiency: changes in hemostatic molecular markers before the onset of thrombosis]

A pregnant woman with congenital antithrombin III (AT III) deficiency was given AT III concentrate and warfarin at the first and after 36th week of gestation periods and at the other gestation period, respectively. The patient developed thrombosis in the left leg, but fibrinopeptide A (FPA) and thrombin-AT III complex (TAT) had already shown high values one week before, suggesting the possibility of their being forecast markers of thrombosis. The administration of AT III concentrate caused an improvement in thrombosis. Therefore, in case of high FPA and TAT values as determined one or two times a week, the administration of AT III concentrate was thought necessary. In case of warfarin, however, non-administration during the 6th-9th weeks of gestation for the purpose of avoiding teratogenicity and frequent blood coagulation tests taking heed of overdosage for the purpose of avoiding fetal central nervous system abnormalities were suggested necessary. Delivery was uneventful, both mother and child being doing very well; umbilical blood AT III activity was 18%. It is generally difficult for us to form the diagnosis as AT III deficiency only from AT III activity at neonatal stage, but in the present study, we analyzed the restriction fragment length polymorphism of the AT III gene using umbilical blood, and succeeded in diagnosing the neonatal child as AT III deficiency.     

Severe Antithrombin III Deficiency in a Patient with Pre-Eclampsia.

Severe acquired antithrombin III (AT III) deficiency was observed in a patient with severe pre-eclamptic toxaemia. Plasma AT III concentration of 0.25 U/ml was found in both functional and immunological assays. The patient was treated with human AT III concentrate as a result of the development of progressive disseminated intravascular coagulation (DIC), the further deterioration of renal function, the risk for thromboembolic complications and the possible adverse effects of heparin therapy. The selective correction of AT III activity resulted in a rapid disappearance of coagulation abnormalities. The patient underwent uncomplicated caesarian section. This observation indicates that acquired severe AT III deficiency may occur as an early feature of DIC in severe pre-eclamptic toxaemia.     

Familial Functional Antithrombin III Deficiency

A family with a tendency to thrombosis and decreased antithrombin III (AT III) activity in plasma, but normal immunoreactive AT III is reported. 7 members of the family had the AT III defect, 4 of whom have had thrombotic episodes. The importance of biological determination of AT III when studying patients with recurrent thrombotic episodes is emphasized.     

Acquired factor X and antithrombin III deficiency in a patient with primary amyloidosis and nephrotic syndrome

A 45-year-old man with primary amyloidosis was initially seen with nephrotic syndrome. Factor X was found to be 5% and antithrombin III (AT III) 45% of normal plasma values. During an 11-month period, despite severe factor X deficiency, the patient did not have any bleeding complications. He developed progressive renal failure and AT III levels increased to normal, at which time he developed severe bleeding complications. These findings suggest a protective role of AT III deficiency against bleeding in a patient with severe factor X deficiency.     

Biology of recurrent venous thrombosis

Important recent advances in the field of the biology of recurrent venous thrombosis include greater understanding of congenital deficiency states involving antithrombin III (AT III) and protein C. Other disturbances demonstrated were related to fibrinolysis frequently, and rarely platelet function and coagulation factors. Possible existence of these anomalies requires investigation during biologic tests in cases of recurrent venous thrombosis, particularly in the presence of a family history or onset of the initial affection before 40 years of age. Confirmation of the importance of screening for such anomalies is supplied by results of a study of 11 families with antithrombin III deficiency and 9 families deficients in protein C, and a literature review of cases. However, currently available biologic tests provide data enabling only partial explanation of the mechanism underlying recurrent venous thrombosis accidents.