SummaryThe role of natural anticoagulants, fibrinolytic cascade factors and common prothrombotic gene polymorphisms in modulating disease severity were studied in 35 'clinically mild' and 37 'clinically severe' haemophilia patients with severe factor VIII or IX deficiency (<0AE01 IU/ml). Strong association of deficiencies of proteins C and S, antithrombin III, tissue factor pathway inhibitor and tissue plasminogen activator, together with factor V Leiden and endothelial protein C receptor 23 bp insertion polymorphisms were observed in the 'clinically milder' group as compared with the 'clinically severe' group. These results indicate a synergistic modulation of bleeding tendency in haemophilia patients by factors in the anticoagulant and fibrinolytic systems.

Glanzmann's thrombasthenia is an autosomal recessive disorder, rare in a global context, but a relatively more common platelet function defect in communities where consanguineous marriages are more frequent. On clinical grounds alone, it cannot be distinguished from other congenital platelet function defects. Epistaxis, gum bleeding, menorrhagia are the common clinical manifestations, whereas large muscle hematoma or hemarthrosis seldom occur in these patients. Essential diagnostic features are a normal platelet count and morphology, a greatly prolonged bleeding time, absence of platelet aggregation in response to ADP, collagen, epinephrine, thrombin and to all aggregating agents which ultimately depend on fibrinogen binding to platelets for this effect, flow cytometry, studies of GPIIb-IIIa receptors on the platelet membrane surface using monoclonal antibodies. The present review describes some of the uncommon features of the disorders and the currently available options which the treating physicians should be aware of during the management of these patients. Although by definition all patients with Glanzmann's thrombasthenia have a virtually complete failure of platelet aggregation, a number of variant forms of GT have been described in which the glycoproteins are present in normal or near normal amounts but are functionally defective. Understanding the pathophysiology of the disorder by the treating physicians is of utmost importance. Presence of high affinity platelet receptors resulting in thrombasthennia-like phenotype may require an antagonistic treatment atypical of classical GT management. It has now been established that different genetic mutations of either GPIIb or IIIa genes results in such a heterogeneity of thrombasthenia phenotype. Glanzmann's thrombasthenia is a paradigm for treating coronary artery disease patients with GPIIb-IIIa antibody and inhibitors. By using these medicines we create a temporary GT-like situation. Hence, understanding this disease is of utmost importance to the practicing cardiologist. As mutations for different variant forms of GT become known, our understanding of how GPIIb-IIIa molecules can be activated to act as a receptor for fibrinogen molecules will be increased. Such understanding undoubtedly will help us to devise better drugs with GPIIb-IIIa inhibitors. Molecular biology techniques have enabled us to equivocally detect heterozygote carriers who are clinically asymptomatic. However, there may be several laboratories in the developing world, which have no access to molecular biology techniques. Development of more robust techniques of quantitation of platelet receptors has enabled an accurate diagnosis of heterozygote carriers or an unborn fetus in the second trimester. The importance of the GPIIb-IIIa polymorphisms in carrier and prenatal diagnosis has not been properly studied. Nowadays the less direct method of PLA1 typing (determination of the levels of platelet antigen) of the foetal platelets as early as 16 weeks of intrauterine life can be used for prenatal...

Four hundred and seven patients (352 haemophilia A and 55 haemophilia B) were investigated for the presence of factor VIII and IX inhibitors. Twenty-four out of 292 severe and two out of 36 moderate haemophilia A patients showed the presence of inhibitors. The mean age at development of inhibitors was 17.7 years (range 6-52 years). In 12 patients the inhibitors were detected due to suboptimal response to factor replacement therapy (symptomatic) and in the remaining 14 patients the inhibitors were detected during the routine screening of the patients' samples for inhibitors. They had, however, responded well to the usual doses of factor concentrates and there was no suspicion in these patients that they had developed an inhibitor (asymptomatic). There were two families in which the inhibitors were detected in more than one family member. The level of inhibitors in symptomatic patients ranged from 2.2 Bethesda units (BU) mL(-1) to 460.6 BU mL(-1), and in asymptomatic patients it ranged from 0.8 BU mL(-1) to 3.2 BU mL(-1). The inhibitors persisted in all patients except one, who developed an inhibitor postoperatively for a brief period of 3 months. All these patients were followed up from first factor exposure and were tested for inhibitors at least twice a year. The mean number of exposure days before they developed inhibitors was 47.5 exposure days (range 17-98 exposure days). No inhibitors appeared after more than 100 exposure days in any of the patients. When 50 consecutive patients were investigated for intron 22 inversions of the factor VIII gene, 17 patients were found to be positive for inversions (10 proximal inversion; seven distal inversion) out of whom four patients developed inhibitors, three patients belonging to the same family. Out of 35 haemophilia B patients, only one patient developed an inhibitor. The overall prevalence of inhibitors was thus 8.2%, which is similar to the reports from western countries, prior to the introduction of highly purified factor concentrate therapy.

As compared to haemophilia, although the clinical features and the management strategies for rare coagulation factor deficiencies are discussed, little is known about them. This study was undertaken to assess the distribution, clinical presentation and treatment of patients with rare coagulation factor deficiency disorders in a cross-sectional population of India. Blood samples and other clinical details from patients suspected of rare coagulation factor deficiencies were collected by the Haemophilia Treatment Centers across India and were diagnosed at National Institute of Immunohaematology, Mumbai. A total of 321 cases of rare clotting factor deficiencies were diagnosed, of which 88% were severe, 10% moderate and 2% mild. Commonest deficiency encountered was factor XIII (FXIII) (30%) followed by FX (15.6%), FVII (15%), fibrinogen (12.1%), FXI (9%), combined V and VIII deficiency (5.6%) and congenital multiple vitamin K-dependent coagulation factor deficiency (MCFD, 2.1%). Major representation of these deficiencies was from Southern and Western India (82%). Mucocutaneous bleeding was the commonest clinical presentation (59%); intracranial (IC) haemorrhage was seen in 18% of the patients; menorrhagia was an important clinical pointer in women in the reproductive age group (78%); 8% of the severe cases had no history of bleeding and 73% of the FXIII deficiency cases had umbilical stump bleeding. The major therapeutic products used was fresh frozen plasma (64%), cryoprecipitate (15%), whole blood (15%), antifibrinolytics (5%) and recombinant FVIIa (1%). A distinct pattern in the distribution of rare clotting factor deficiencies was observed which was based on multiple factors that include ethnicity and the available diagnostic facilities in different regions of this vast country.

The JAK2(V617F)mutation is recurrent in polycythemia vera and essential thrombocythemia, which are myeloproliferative neoplasms frequently associated with arterial and venous thromboembolism. It has also been reported as a marker for occult myeloproliferative disorder (MPD) in patients with splanchnic venous thrombosis. Limited data are available regarding the prevalence of the JAK2(V617F) mutation in patients with thrombosis outside the splanchnic region. For the study, 321 cases of venous thrombosis in the splanchnic and nonsplanchnic regions (cerebral venous thrombosis [CVT], 70; deep venous thrombosis [DVT], 36; Budd-Chiari syndrome [BCS], 137; portal venous thrombosis [PVT], 78) were studied for the presence of JAK2 mutations. The prevalence values for the JAK2 mutation were 3% (1/36), 8.8% (12/137), 5% (4/78), and 3% (2/70) in DVT, BCS, PVT, and CVT, respectively; 19 (5.9%) of 321 cases were positive for the JAK2 mutation. Of 111 healthy subjects screened for this mutation, none were found to be carriers. Determination of the JAK2(V617F) mutation may be useful to identify patients who should be carefully observed for the development of overt MPDs. The significance of screening for this mutation in nonsplanchnic thrombosis cases needs to be analyzed in a larger series.