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PubMed2000

Molecular bases of antithrombin deficiency in French families: identification of seven novel mutations in the antithrombin gene.

We have investigated the molecular bases of familial antithrombin deficiency in eight French families. Eight mutations in the antithrombin coding exons were identified, seven of which were novel mutations. In all cases, individuals were heterozygous for the mutation. We found two small frameshift deletions in exon 3a, leading to type I deficiency. Five missense mutations in exons 3b or 5 also caused type I deficiency and their potential consequences on the antithrombin three-dimensional structure were analysed. The last mutation in exon 4 was associated with a type II 'reactive site' deficiency: a dysfunctional antithrombin that is affected in its interaction with thrombin was present in circulation.

Antithrombin III Deficiency↗
PubMed2005

[Study on the molecular mechanism of antithrombin gene C2759T (Leu99Phe) mutation causing antithrombin deficiency].

OBJECTIVE: To study the molecular mechanism of antithrombin (AT) gene C2759T (Leu99Phe) mutation causing AT deficiency. METHODS: A mutated AT cDNA expression plasmid ATM2759 was constructed by mega-primer method. ATM2759 and wild type AT cDNA expression plasmid ATN were transfected into COS7 cells or CHO cells by using Superfect reagent respectively for in vitro expression study and immunofluorescence assay. RESULTS: The antigen levels of AT (AT:Ag) in the cell lysate of ATM2759 transfected COS7 cells and the cell culture supernatant were 174.97% and 35.63% of that of ATN transfected COS7 cells respectively, whereas the AT activity in the cell culture supernatant was 47.73% of the control's. Immunofluorescence analysis showed that the fluorescence intensity was significantly higher in ATM2759 transfected CHO cells than in those transfected with ATN. CONCLUSIONS: Leu99Phe substitution may not affect the binding capacity of AT with heparin. Secretion defect and intracellular accumulation of the mutated AT protein might be the mechanisms of this mutation causing AT deficiency.

Animals↗
PubMed2006

The risk of recurrent venous thromboembolism in patients with inherited deficiency of natural anticoagulants antithrombin, protein C and protein S.

Few data are available on the risk of recurrent venous thromboembolism (VTE) associated with the rare inherited deficiencies of natural anticoagulants. We studied 602 patients with previous VTE: the incidence of first recurrence in the absence of anticoagulation was retrospectively estimated in 64 patients with deficiency of antithrombin (AT, n=14), protein C (PC, n=28), or protein S (PS, n=22) and 538 with no known defect, who acted as the reference group. After adjustment for sex, age, and circumstances of the first event, AT deficiency resulted an independent risk factor for recurrence (hazard ratio 1.9, 95% CI 1.0-3.9); the carriers of PC or PS deficiency had a marginal increase in risk (hazard ratio 1.4, 95% CI 0.9-2.2). In conclusion, patients with AT deficiency are potential candidates for long-term oral anticoagulation.

3' Untranslated Regions↗
PubMed1998

[Genetic diagnosis of hereditary coagulation disorders].

Genomic abnormalities responsible for blood coagulation disorders have been the subject of extensive investigations for the last several years. Application of the methods of molecular biology had markedly increased the faculty of genetic diagnosis. Recently, we performed DNA sequence analysis of 7 families with type I antithrombin deficiency and 2 families with factor VII deficiency by polymerase chain reaction/direct DNA sequencing method. Here, we present the results of our studies. In addition, we address genetic basis of activated protein C resistance and a novel R485K polymorphism of the factor V gene in the Japanese.

Antithrombin III Deficiency↗
PubMed1982

[Study of coagulation and fibrinolysis in 131 cases of recurrent deep vein thrombosis].

The study concerns 131 patients with a history of recurrent deep vein thrombosis. The predisposing and triggering factors of thrombosis have been carefully recorded and a study of hemostasis parameters has been performed, including AT III determination, fibrinolytic activity before and after venous occlusion, plasminogen, alpha 2-antiplasmin and histidine-rich glycoprotein determination. A congenital AT III deficiency was detected in six patients (4.4%). The most frequent finding was a decrease in fibrinolytic activity after venous occlusion. If one accounts for patients with a disease predisposing to thrombosis: Behçet's disease, cancer, hiatus hernia, Cockett's syndrome (14 patients), or a biological anomaly such as: deficiency in AT III, decrease in fibrinolytic activity. circulating anticoagulant, increase in lipids or uric acid, decrease in plasminogen or increase in alpha 2-antiplasmin (57 patients), there are still 60 patients (45% of the cases) in whom thromboses remain unexplained.

Adolescent↗
PubMed2000

Alpha(2)-macroglobulin levels are high in adult patients with congenital antithrombin deficiency.

Antithrombin is responsible for about 80% of the progressive inhibitory activity of thrombin in human plasma. The role of other protease inhibitors known to inhibit thrombin is not completely clarified. However, their contribution may become relevant when antithrombin is low. We elected to investigate adult patients with congenital antithrombin deficiency to assess the concentration of other naturally occurring thrombin inhibitors such as alpha(2)-macroglobulin, alpha(1)-antitrypsin, heparin cofactor II, and C(1)-inhibitor. The study included 59 patients with congenital antithrombin deficiency with and without a previous history of thrombosis, together with an equal number of control subjects matched for age and sex. Statistically significant differences (patients vs. controls) were observed only for alpha(2)-macroglobulin (i.e., 120 vs. 102%, p<0.01). Further analysis of antithrombin-deficient carriers with and without a past history of thrombosis showed that alpha(2)-macroglobulin levels were higher than the 90th percentile of control distribution more often in asymptomatic than symptomatic men (odds ratio=0.04; confidence interval=0.003-0.60), but not in women (odds ratio=2.14; confidence interval=0.35-13.1). In conclusion, results from this cross sectional study showed that alpha(2)-macroglobulin levels were high in patients with congenital antithrombin deficiency. Furthermore, the high levels were found more often in asymptomatic than symptomatic men. Whether this increase provides protection against thrombosis should be evaluated in a prospective study.

Adolescent↗
PubMed1995

Thrombocytopenia, antithrombin deficiency and extensive thromboembolism in pregnancy: treatment with low-molecular-weight heparin.

Pregnancy limits the therapeutic options for managing thrombocytopenia which occurs in 5% of patients on heparin. We describe a case of extensive thromboembolism associated with antithrombin (AT) deficiency complicated by thrombocytopenia which resolved when low-molecular-weight heparin was instituted. A primigravid woman presented at 11 weeks gestation with bilateral femoral occlusive thrombi extending above the renal veins. Investigations revealed AT deficiency, thrombocytopenia and renal infarction. After low-molecular-weight heparin was substituted for unfractionated heparin, the thrombocytopenia resolved and although the pregnancy was lost, the patient made a full recovery.

Adult↗
PubMed1997

Lipoprotein (a): its role in childhood thromboembolism.

PURPOSE: Elevated lipoprotein (a) [LP (a)] concentrations are independent risk factors of coronary heart disease or stroke in young adults. To clarify its role in childhood thromboembolism, Lp (a) was measured in 72 children with thromboembolism. METHODS: In addition to Lp (a), defects of the protein C anticoagulant system, antithrombin, and antiphospholipid antibodies were investigated in children with arterial (n = 36) or venous (n = 36) thrombosis. RESULTS: Enhanced Lp (a) >50 mg/dL was diagnosed in 8 out of 36 children with arterial and 5 out of 36 patients with venous thrombosis. Of the 72 children, 25 showed the factor V Leiden mutation, 10 showed protein C deficiency, 2 showed antithrombin deficiency, and 4 showed primary antiphospholipid syndrome. Three children with increased Lp (a) were heterozygous for the factor V Leiden mutation, and 1 girl showed additional protein C deficiency. CONCLUSIONS: Data of this study indicate that increased concentrations of Lp (a) play an important role in childhood thrombosis.

Adolescent↗
PubMed1995

A review of mutations causing deficiencies of antithrombin, protein C and protein S.

The mutations observed in patients with antithrombin and protein C deficiencies are mostly substitutions of one nucleotide, or deletions/insertions of fewer than 10 nucleotides in the exons and intron-exon junctions. These genomic abnormalities result in missense changes (involving aminoacids important for protein folding), aberrant polypeptide chains and/or premature termination codons, or abnormal splicing precluding DNA transcription. The number of mutations so far identified is such that it is difficult to use genomic DNA analysis for diagnostic purpose. However, identification of the gene defect can be useful in well-defined situations, such as the risk of homozygosity, and complex or ambiguous plasma phenotypes, which frequently occur in protein C deficiency. Protein S deficiency, the molecular bases of which have been less extensively studied, is due to micromodifications of the coding sequence in only half the cases investigated so far. The mechanisms involved in the remaining cases remain to be identified.

Alleles↗
PubMed2002

Prevalence of inherited thrombophilia in young thrombosis patients from the East Bohemian region.

Venous thromboembolism is a multifactorial disease that is defined by multiple interactions between genetic and environmental components. Inherited thrombophilia may result in a hypercoagulable state that causes an increased tendency to thrombosis. We assessed the prevalence of factor V Leiden, factor II 20210A, antithrombin III, protein C and protein S deficiency, and the presence of antiphospholipid syndrome among 325 thrombosis patients from the East Bohemian region with a first episode of thrombosis under the age of 45 years. The average age of the first thrombotic event was 34 years (age range, 14-45 years). These data are not known yet from this part of the Czech Republic. Factor V Leiden was found in 40%, factor II 20210A in 6%, antithrombin III deficiency in 4%, protein C deficiency in 6%, and protein S deficiency in 11% in this cohort. Lupus anticoagulant was detected in 8% and anticardiolipin antibodies in 6%. Our results confirm the usefulness of thrombophilia work-up in patients with venous thrombosis before the age of 45 years in our region. The diagnosis of inherited thrombophilia is important for further management of these patients.

Adolescent↗
PubMed2003

Five novel and four recurrent point mutations in the antithrombin gene causing venous thrombosis.

We analyzed the antithrombin (AT) gene in 9 unrelated Japanese patients with thrombotic disease. All 7 exons, the splice junctions, and the 5'-flanking region of the AT gene were amplified by polymerase chain reaction and sequenced directly. Nine different point mutations, all in the heterozygous state, were identified. Five novel (M-32T, M89K, L146H, Q159X, and L409P) and 2 previously reported (R132X and R359X) point mutations were identified in patients with type 1 deficiency. Two different missense mutations, R393C and R393H, located in the protease reactive site were detected in patients with type 2 deficiency. No other sequence abnormalities in the AT gene were detected by direct sequencing. None of the mutations was present in 100 alleles from 50 unrelated Japanese control subjects Although type 1 deficiency was diagnosed in patient 7 on the basis of approximately 50% AT antigen and activity levels, the data indicated that the novel L409P mutation is a type 2 pleiotropic effects (PE) deficiency because its location in the C-terminal portion of the reactive site is similar to the locations of reported PE type mutations, and it is highly conserved among other serpins.

Adolescent↗
PubMed1996

Frequency of pregnancy-related venous thromboembolism in anticoagulant factor-deficient women: implications for prophylaxis.

BACKGROUND: It has been reported that women with an inherited deficiency of antithrombin, protein C, or protein S have an increased risk for developing venous thromboembolic disease during pregnancy and the postpartum period. However, because the available data on risk are flawed, it is difficult to define a rational, efficacious, and safe policy about prophylaxis for venous thromboembolism in these women. OBJECTIVE: To determine the frequency of venous thromboembolism during pregnancy and the postpartum period in women with heritable deficiencies of anticoagulant factors. DESIGN: Retrospective cohort study. SETTING: University outpatient clinics in the Netherlands and Italy. PARTICIPANTS: 129 otherwise asymptomatic female family members of patients with a history of venous thromboembolism and an established deficiency of antithrombin, protein C, or protein S. MEASUREMENTS: Medical history, with specific attention to episodes of venous thromboembolism and obstetric history, was taken. The anticoagulant factor status of the study participants was determined. If a patient had an episode of venous thromboembolism, subsequent pregnancies in that patient were not analyzed. RESULTS: Of the 129 women who participated in the study, 60 had anticoagulant factor deficiency and 69 did not. In the nondeficient group, 198 pregnancies occurred; 1 of these (0.5%) was complicated by an episode of venous thromboembolism during the postpartum period. In the deficient group, 169 pregnancies occurred; 7 of these (4.1%) were complicated by an episode of venous thromboembolism during the third trimester of pregnancy (2 pregnancies [1.2%]) and the postpartum period (5 pregnancies [3.0%]). The risk for venous thromboembolism was increased eightfold in deficient women compared with nondeficient women (hazard ratio, 8.0 [95% CI 1.2 to 184]). CONCLUSIONS: Anticoagulant factor-deficient women have an increased risk for venous thromboembolism during pregnancy and the postpartum period. Although data from an appropriate randomized clinical trial are lacking, the frequency of venous thromboembolism seen in deficient women might justify the use of anticoagulative prophylaxis during the third trimester of pregnancy and the postpartum period.

Adolescent↗
PubMed1998

Different risks of thrombosis in four coagulation defects associated with inherited thrombophilia: a study of 150 families.

Deficiency of the naturally occurring anticoagulant proteins, such as antithrombin, protein C and protein S, and activated protein C resistance due to the factor V Leiden gene mutation is associated with inherited thrombophilia. So far, no direct comparison of the thrombotic risk associated with these genetic defects is available. In this study, we wish to compare the lifetime probability of developing thrombosis, the type of thrombotic symptoms, and the role of circumstantial triggering factors in 723 first- and second-degree relatives of 150 index patients with different thrombophilic defects. We found higher risks for thrombosis for subjects with antithrombin (risk ratio 8.1, 95% confidence interval [CI], 3.4 to 19.6), protein C (7.3, 95% CI, 2.9 to 18.4) or protein S deficiency (8.5, 95% CI, 3. 5 to 20.8), and factor V Leiden (2.2, 95% CI, 1.1 to 4.7) than for individuals with normal coagulation. The risk of thrombosis for subjects with factor V Leiden was lower than that for those with all three other coagulation defects (0.3, 95% CI, 0.1 to 1.6), even when arterial and superficial vein thromboses were excluded and the analysis was restricted to deep vein thrombosis (0.3, 95% CI, 0.2 to 0.5). No association between coagulation defects and arterial thrombosis was found. The most frequent venous thrombotic manifestation was deep vein thrombosis with or without pulmonary embolism (90% in antithrombin, 88% in protein C, 100% in protein S deficiency, and 57% in factor V Leiden), but a relatively mild manifestation such as superficial vein thrombosis was common in factor V Leiden (43%). There was a predisposing factor at the time of venous thromboembolism in approximately 50% of cases for each of the four defects. In conclusion, factor V Leiden is associated with a relatively small risk of thrombosis, lower than that for antithrombin, protein C, or protein S deficiency. In addition, individuals with factor V Leiden develop less severe thrombotic manifestations, such as superficial vein thrombosis.

Adolescent↗
PubMed2004

Portal vein thrombosis in children and adolescents: the low prevalence of hereditary thrombophilic disorders.

PURPOSE: The aim of this study was to determine the frequency of thrombophilic disorders in children and adolescents with portal vein thrombosis (PVT) as well as assessing the hereditary character of this disorder. METHODS: A 2-year prospective study was carried out in pediatric PVT patients (n = 14), their parents (n = 25), and an age-matched control group free of liver disease (n = 28). The presence of PVT was assessed by means of Doppler ultrasound scan or angiography. None of the PVT patients presented biochemical or histologic signs of liver disease. RESULTS: The frequency in PVT patients of protein C (PC), protein S (PS) and antithrombin (AT) deficiency was 42.9% (P <.05 v controls), 21.4% (P >.05) and 7.1% (P >.05), respectively. None of the controls or parents of PVT patients presented hereditary PC, PS, or AT deficiency. One PVT patient and one control (P =.999) presented prothrombin G20210A mutation. Homozygous methylenetetrahydrofolate reductase C677T genotype was observed in 3 of 14 (21.4%) PVT patients and in 5 of 28 (17.9%; P =.356) controls. None of these patients presented factor V G1691A mutation. CONCLUSIONS: PC deficiency was frequent in pediatric PVT patients and does not seem to be an inherited condition. The hereditary prothrombotic disorders do not seem to play a vital role in thrombosis in children and adolescents with PVT.

Adolescent↗
PubMed1989

Antithrombin: structure, genomic organization, function and inherited deficiency.

Antithrombin is a major plasma protein inhibitor of proteinases generated during blood coagulation; it plays an important role in the regulation of thrombin in blood. The anticoagulant heparin greatly accelerates the rate of inactivation of proteinases by antithrombin, predominantly through its well defined, highly specific binding reaction with the inhibitor, but also through a less strictly defined interaction with some of the proteinases (such as thrombin). There is evidence for an analogous acceleratory mechanism in vivo, that functions by the binding of antithrombin to a subpopulation of heparan sulphate proteoglycans intercalated in the surface of endothelial cells. The location and structure of the gene for antithrombin are known. Both its overall organization and the structure of the subdomains of the expressed protein can be considered in terms of their relationships to a serine proteinase inhibitor superfamily, which is believed to have evolved from a common ancestor. The region of the antithrombin gene 5' to the coding region has been characterized. Unlike other members of the serpin family, there is no TATA-like promoter sequence. Two enhancer sequences have been identified that are homologous to enhancer regions of other genes. There are two polymorphisms: an intragenic polymorphism arising from a translationally silent A to G transition in codon 305, and a length polymorphism arising from the presence of 32 bp or 108 bp non-homologous sequences 345 bp upstream from the translation initiation codon. Inherited deficiency of antithrombin is associated with familial thromboembolism. The molecular genetic basis of some subtypes of deficiency is increasingly yielding to investigation. It is interesting to note that a number of mutations have been identified in CpG dinucleotides, supporting the suggestion that this dinucleotide sequence may represent a mutation hotspot in the human genome.

Amino Acid Sequence↗
PubMed2005

Changes in antithrombin activity and platelet counts in the late stage of twin and triplet pregnancies.

It is possible that women with triplet pregnancies are more likely to exhibit pregnancy-induced antithrombin deficiency, gestational thrombocytopenia, and perinatal elevation in serum aspartate aminotransferase (AST) than women with twin pregnancies. We retrospectively reviewed changes in antithrombin activity, platelet count, and blood chemistry in 23 twin and seven triplet pregnancies in which the mothers received antenatal care and gave birth in our hospital during 1999 and 2001. Both antithrombin activity and platelet counts gradually decreased until delivery, then promptly increased after delivery in both twin and triplet pregnancies. A significantly larger number of women developed gestational thrombocytopenia of < 100 x 10 (9)/L (43% [three of seven] versus 4.3% [one of 23]; p < 0.01) and pregnancy-induced antithrombin deficiency of < 60% of normal activity (57% [four of seven] versus 17% [four of 23]; p < 0.05) in triplet than in twin pregnancies. Eight women with pregnancy-induced antithrombin deficiency, including three women with gestational thrombocytopenia, were significantly more likely to develop perinatal elevations of AST, lactate dehydrogenase, serum creatinine, fibrin/fibrinogen degradation products, and D-dimer than were those without pregnancy-induced antithrombin deficiency. These findings suggest that women with triplet pregnancies are at an increased risk of the HELLP syndrome and acute fatty liver of pregnancy compared with women with twin pregnancies.

Adult↗
PubMed2001

Homozygous antithrombin deficiency type II (99 Leu to Phe mutation) and childhood thromboembolism.

We report 5 children from 3 families with homozygous antithrombin deficiency type II affecting the heparin binding site (99 Leu to Phe mutation). Four children had severe spontaneous thromboembolic events (deep leg or caval vein thrombosis, ischaemic stroke) at one week, 3 months, 13 and 14 years of age. The fifth patient, a 17 year-old boy was asymptomatic. Early manifestation of homozygous deficiency calls for prompt and accurate diagnosis. In doubtful cases genetic analysis is required. Long-term oral anticoagulation should be considered in affected individuals.

Adolescent↗
PubMed1999

Hereditary and acquired antithrombin deficiency.

Antithrombin (AT) is the most important inhibitor of activated coagulation enzymes. Deficiency of this protein can be a congenital defect. Different types have been described with a diminution of the entire molecule as well as diminution of activity only with normal concentration and normal activity and concentration but with a decreased sensitivity to heparin. There exist also different types of acquired deficiency due to a diminished production, an increased loss or an increased consumption of the inhibitor. Because AT deficiency is the cause of an increased thrombotic tendency in many cases the therapeutic and prophylactic possibilities are described. Since highly purified concentrates became available, substitution was attempted in cases of AT deficiency. It was found to be of greatest importance in cases of disseminated intravascular coagulation (DIC) which is a frequent consequence of septic or traumatic shock. In such cases an adequate AT-substitution can even be lifesaving as could be shown in different trials.

Animals↗