(ATT) trinucleotide repeats in the antithrombin gene and their use in determining the origin of repeated mutations

Two (ATT) trinucleotide repeat polymorphisms have been identified in the tails of Alu repeat elements in intron 5 of the antithrombin gene. The frequency and distribution of allele sizes for the Alu 5 and Alu 8 tail polymorphisms have been defined in a sample Caucasian population. The Alu 5 polymorphism has two alleles while that of Alu 8 has 10 alleles with a heterozygosity of 0.83. These polymorphisms have been used in combination with four previously described polymorphisms within the antithrombin gene to construct antithrombin gene haplotypes in the sample Caucasian population. Twenty-two different haplotypes were observed, with the Alu 8 polymorphism being particularly useful in subdividing the core haplotype based on the previously identified polymorphisms. The haplotype data were used to investigate the origin of repeat mutations within the antithrombin locus. We compared the haplotypes associated the mutant antithrombin genes in five families with the mutation 2759C→T (L99F) and five families with the mutation 5381C→T (R129Stop). The mutation 2759C→T (L99F), which occurs within a non-CpG dinucleotide, was carried on a gene associated with an identical haplotype in each of the five families. The mutation 5381C→T (R129Stop), a single base substitution within a CpG dinucleotide, was associated with at least two different haplotypes. The findings suggest a founder effect in the five families sharing the 2759C→T (L99F) and at least two independent origins for the CpG dinucleotide mutation 5381C→T (Rl29Stop). © 1994 Wiley-Liss, Inc.     

Modulation of hemostatic balance with antithrombin III replacement therapy in a case of liver cirrhosis associated with recurrent venous thrombosis

Patients with liver failure can present both thrombotic and hemorragic complications because of the deficiency in coagulation factors and inhibitors (protein C and S, antithrombin III) and impairment of fibrinolytic balance. Here we report the case of a 63-year-old man with liver cirrhosis, recurrent thrombosis, and features of low-grade consumption coagulopathy, showing severe antithrombin III deficiency (about 30% of normal values). Treatment with antithrombin III (2000 U/day) and low doses of heparin (5000 U b.i.d.) was successful in modulating the coagulation system toward an antithrombotic effect. After discharge from hospital the ambulatory treatment with antithrombin III concentrates (2000 U twice a week) allowed the attainment of antithrombin III activity of about 60% and prevented the patient from recurrence of venous thrombosis.Abbreviations AT-III Antithrombin III - DIC Disseminated intravascular coagulation - TAT complexes Thrombin-antithrombin III complexes - PAI-1 Plasminogen activator inhibitor-1     

ANTITHROMBIN III SUPPLEMENTATION IN CHILDHOOD ACUTE LYMPHOBLASTIC LEUKEMIA TREATED WITH L-ASPARAGINASE

The change of plasma antithrombin III (AT) levels after supplementation of AT concentrates was examined in ALL children with acquired AT deficiency following L-asparaginase (ASP) administration. The patients received AT concentrates of 34.5 &#45 7.6 U/kg. The increase of plasma AT activity and antigen was 2.07 &#45 0.62% and 0.70 &#45 0.16 mg/dL per unit AT infused per kilogram of body weight, respectively. The activity decreased to 62.0 &#45 7.7% of the peak values by 48 hours after supplementation. The administration of AT concentrates constantly increased the plasma AT activity in ALL children treated with ASP, which may minimize the acquired prothrombotic state.     

FAMILIAL DEFICIENCY OF ANTITHROMBIN 111: EVIDENCE FOR HETEROGENEITY EXISTING WITHIN THE FAMILY

An Australian family with familial antithrombin Ill (AT III) deficiency is described. The deficiency inherited in an autosomal co-dominant manner is characterised by proportionate reduction in antigenically and biologically measured AT III. Some members with AT Ill deficiency have had major venous thromboses, and the deficiency has possibly been the cause of death in two individuals in the family. Heterogeneity was observed in laboratory and clinical findings in this family.     

Evidence for a hyperglycaemia-dependent decrease of antithrombin III-thrombin complex formation in humans

Summary In the presence of increased levels of fibrinopeptide A, decreased antithrombin III biological activity, and thrombin-antithrombin III complex levels are seen in diabetic patients. Induced-hyperglycaemia in diabetic and normal subjects decreased antithrombin III activity and thrombin-antithrombin III levels, and increased fibrinopeptide A plasma levels, while antithrombin III concentration did not change; heparin was shown to reduced these phenomena. In diabetic patients, euglycaemia induced by insulin infusion restored antithrombin III activity, thrombin-antithrombin III complex and fibrinopeptide A concentrations; heparin administration had the same effects. These data stress the role of a hyperglycaemia-dependent decrease of antithrombin III activity in precipitating thrombin hyperactivity in diabetes mellitus.     

Erythrocytic phosphatidylserine exposure and hemostatic alterations in β-thalassemia intermediate patients

Introduction

Hypercoagulable state is one of the common findings in beta-thalassemia intermedia (β-TI), particularly in splenectomized patients, with infrequent blood transfusion. Abnormality of the red blood cells (RBC) membrane due to oxidative damage is suggestive of possible etiologies. Membrane lipid peroxidation increases the exposure of phosphatidylserine (PS) that plays a role in the activation of coagulation factors V and X, subsequently initiating thrombosis. Our aim of this study was to find the probable correlation of the alteration of the PS on the RBC outer membrane with the hypercoagulable state in the β-TI patients.

Materials and methods

Our cross-sectional study was conducted on 39 splenectomized β-TI patients and 38 age-matched healthy controls. The mean age was 37 years. Analysis of the PS exposure on the RBCs was performed by fluorescein isothiocyanate (FITC) conjugated AV protein .Measurement of the coagulation factors X, V and antithrombin III (AT-III) was performed. We also checked the D-dimer levels .Analysis was performed by SPSS16.

Results

Fluorescence of FITC-Annexin V labeling on patients RBCs were higher than healthy controls; (2.8 ± 2.2%) of the patients versus (0.4 ± 0.18%) in the control group and was statistically significant (P < 0.05). Mean levels of factor X and AT-III of the patients as compared with the control group decreased and showed significant difference (P < 0.05).

Conclusions

Circulation of thalassemic RBCs, which abnormally possess PS on RBC membrane outer surface, suggests the possibility of the gradual consumption of the coagulation factors in the presence of a chronic coagulability state.     

Normal reference ranges of antithrombin,protein C and protein S: Effect of sex,age and hormonal status

Introduction

Antithrombin (AT), protein C (PC) and protein S (PS) deficiencies are risk factors for venous thromboembolism. Overlapping values between heterozygous carriers and normal individuals often make a correct classification of a deficiency difficult. The aim of this study was to investigate the effect of sex, age, menopause and hormone therapy on natural anticoagulant plasma levels in a large group of healthy individuals, and to evaluate the need of separate reference ranges.

Materials and Methods

AT and PC were measured with a chromogenic assay, antigenic free PS with an ELISA test. To evaluate the effect of sex, age, oral contraception, hormonal status (and their interaction) on AT, PC and PS levels, linear regression models were used. Biological relevance and the value of the normal deviate z were chosen as rules to decide for separate reference ranges.

Results

The study population consisted of 1837 healthy adult individuals (741 men, 1096 women), aged 18-85 years (median age: 44 years). In men AT levels decreased after the age of 50 years. Men had higher levels of PS than women, particularly at young ages. In women, after correction for menopause, only PC levels increased with age. Menopause affected AT and PS, but not PC levels. Oral contraceptive intake was associated with a decrease of AT and PS, and an increase of PC levels.

Conclusions

For AT, PC and PS, sex- and age-specific normal reference ranges can be useful, in order to better discriminate true carriers of a natural anticoagulant deficiency.     

A retrospective study on oral anticoagulant prophylaxis in 103 Italian patients with hereditary thrombophilia and thrombosis

Summary The clinical records of 103 Italian patients with inherited thrombophilia and thrombosis were reviewed to estimate the incidence of thrombotic recurrences and major bleeding complications according to the different duration of oral anticoagulant prophylaxis (OAP). The incidence of the first thrombotic recurrence was 2.9, 7.4 and 10.8×100 patients/year, respectively, in subjects receiving lifelong OAP, stopping OAP after a mean of 9 months (range 1–30 months) or not receiving OAP. The probability to remain free from thrombotic recurrences in patients undergoing lifelong OAP, as estimated by the Kaplan-Meier method, was significantly higher in comparison with untreated patients (p<0.001), but did not reach the statistical significance in comparison with patients who stopped prophylaxis. The incidence of further thrombotic recurrences was 1.2, 21.1 and 22.3×100 patients/year, respectively, in the three groups defined above. The difference between patients who prolonged indefinitely OAPvs those who stopped or did not receive OAP was statistically significant (p=0.003). Two intracranial bleedings, one of which fatal, were observed in patients undergoing lifelong OAP, whereas no major bleeding complications occurred in the other two groups. Our study supports the recommendations to continue indefinitely OAP in patients with inherited thrombophilia and recurrent thrombosis, but suggests caution in starting lifelong prophylaxis soon after the first thrombotic event in all patients. Members of the Study Group: F. Baudo (Milano); M. Berrettini (Perugia); G. Castaman (Vicenza); N. Ciavarella (Bari); S. Coccheri (Bologna); V. De Stefano (Roma); A. G. Dettori (Parma); N. Erba (Merate); G. Leone (Roma); P. M. Mannucci (Milano); C. Manotti (Parma); M. G. Mazzucconi (Roma); G. Palareti (Bologna); F. Panicucci (Pisa); E. Pogliani (Monza); F. Rodeghiero (Vicenza); A. Tripodi (Milano).