凝血因子Ⅷ内含子ⅩbaⅠ多态位点检测及其在血友病A产前诊断中的应用

目的建立凝血因子Ⅷ（FⅧ）基因内含子22的Ⅹba Ⅰ多态位点高特异的基因连锁分析法，并应用于血友病A（HA）家系中孕妇携带者检测及产前基因诊断。方法用长距离PCR特异性扩增206个无血缘关系个体中FⅧ基因内含子226．2kb片段并进行Ⅹba Ⅰ酶切，计算Ⅹba Ⅰ多态性位点的基凶频率和多态信息量；用内含子22例位检测及FⅧ基因内Ⅹba Ⅰ，BclⅠ，HindⅢ和（CA）n二核苷酸重复序列多态性位点和FⅧ基因外DXS52多态性位点对20个HA家系进行间接基因诊断。结果ⅩbaⅠ多态性位点的基因频率和多态信息量分别是0．5475和0．4955；20个HA家系中，7个为内含子22倒位，13个非倒位家系中有6个家系Ⅹba Ⅰ均提供多态信息，其中2个家系只能用Ⅹba Ⅰ作出分子诊断，诊断率达46．15％；两个或两个以上连锁分析方法均提供多态信息的有8个家系。结论改进的FⅧ基因内Ⅹba Ⅰ多态位点是一个特异性高，信息量大的分子诊断标志。联合用22内含子倒位及Ⅹba Ⅰ等5种间接检测方法大大地提高了HA基因诊断率。是防止患儿出生，阻断致病基因传递的有效措施。     

Genetic analysis of non-severe hemophilia A phenotype with A discrepancy between one-stage and chromogenic factor VIII activity assays

IntroductionThe diagnosis of hemophilia A (HA) is based on the measurement of factor VIII activity (VIII:C). About one-third of non-severe HA patients show a discrepancy of VIII:C measured by one-stage (VIII:C 1st) and chromogenic (VIII:C chr) assays. Different mutations in the F8 gene may cause the discrepancy in results of the FVIII activity assay.The aim of this study was to investigate F8 gene mutations in patients with assay discrepancies and to evaluate their impact on the results of VIII:C assays.MethodsMutation analysis was performed on 41 individuals with a discrepancy in VIII:C 1st and FVIII: C chr assays by direct sequencing. In addition, the effect of the variants on FVIII macromolecule structure was investigated by in silico and bioinformatics tools.ResultsGenetic analysis disclosed 22 different variants, of which 19 were identified for the first time to be involved in the phenotype of VIII:C discrepancy. Most of the variants related to the higher VIII:C 1st were found in A1, A2, A3 domains. The variant related to VIII:C chr > VIII:C 1st was located in the thrombin cleavage site. In silico analysis showed the effect of variants on FVIII macromolecule stability, which may be the possible mechanism causing the discrepancy.ConclusionOur data shed light on the impact of genetic defects on VIII:C assay and provided evidence that the consideration of these mutations may open a new window to the proper diagnosis and treatment monitoring of non-severe HA patients.     

Haemophilia and thrombophilia. What do we learn about combined inheritance of both genetic variations?

For the study presented here 135 pediatric PUP patients with haemophilia consecutively admitted to German pediatric haemophilia treatment centers were investigated. In addition to factor VIII activity, the factor V (FV) G1691A mutation, the factor II (FII) G20210A variant, methylenetetrahydrofolate reductase (MTHFR) T677T genotype, elevated lipoprotein a (Lp a), antithrombin, protein C, and protein S were investigated. 103 out of 122 HA patients (FVIII activity <1%) were suffering from severe HA. The prevalence of prothrombotic risk factors in children with severe haemophilia A (HA) did not differ from previously reported data: FV GA 5.8%, FII GA 3.9%, MTHFR TT 10%, elevated Lp a 7%, protein C type I deficiency 1.1%. The first symptomatic bleeding leading to diagnosis of severe haemophilia occurred with a median age of 1.6 years (range: 0.5-7.1 years) in children carrying prothrombotic risk factors compared to non-carriers (0.9 years (0.1-4.0; p = 0.01). Two patients presenting with neonatal stroke due to elevated Lp a and the FII GA variant showed haemorrhagic stroke transformation triggered by severe haemophilia. In addition, when haemophilia A was corrected by administration of factor VIII concentrates eight out of 25 children with central lines in place developed catheter-related thrombosis. Conclusion: The data of this multicentre cohort study demonstrate that the clinical phenotype of severe haemophilia A in childhood is clearly influenced by the coinheritance of prothrombotic risk factors.     

Analysis of mRNA in hemophilia A patients with undetectable mutations reveals normal splicing in the factor VIII gene

BACKGROUND: haemophilia A (HA) is characterized by partial or total deficiency of factor VIII (FVIII) protein activity. It is caused by a broad spectrum of mutations in the FVIII gene. Despite tremendous improvements in mutation screening methods, in about 2% of HA patients no DNA change could be found, even after sequencing the whole coding part of the FVIII gene including the flanking splice sites, as well as the promotor and the 3' UTR regions. OBJECTIVES, PATIENTS AND METHODS: In the present study we performed a detailed RNA analysis of three groups of patients. The first included control patients with known splicing defects, the second included two patients with already identified nucleotide changes close to splicing sites, that could potentially alter the normal splicing process, and a third group of 11 unrelated patients whose genomic DNA have already been screened for mutations by DHPLC and direct sequencing with no mutation being identified. RESULTS: Both candidate splice site mutations were shown to result in either skipping or alternative splicing of at least one exon, therefore these DNA changes must be considered as causal for the patients' HA phenotype. In contrast, no abnormalities on the RNA level were observed in any of 11 unrelated patients without mutations in the FVIII gene. CONCLUSIONS: These findings exclude mutations that could be located deep in the introns and affecting either normal splicing or lead to mechanisms causing some unknown rearrangements of the FVIII gene. In fact, our results point to the presence of still unknown factor(s) causing HA, which might be either allelic or in the close proximity of the FVIII gene or non-allelic associated with other genetic loci that are involved in the processing of the FVIII protein.     

Successful eradication of a FVIII inhibitor in a 60-year-old patient with mild haemophilia A using single-agent prednisolone

Background: Development of FVIII inhibitors represents a major challenge in patients with mild haemophilia A (HA), because they tend to occur at an older age and classical immune tolerance induction appears to be less effective. Case report: A man (age: 60 years) with mild HA due to the missense mutation, Leu1929Arg, received a single dose of rFVIII at 35IU/kg prior to routine colonoscopy, totalling 25 lifetime exposure days. Two months later, rFVIII was infused for a traumatic hip haematoma. However, FVIII recovery was inappropriate, and a FVIII inhibitor of 19 BU with type-2 kinetics was detected, resulting in FVIII:C of <1%. Two weeks later, the patient experienced spontaneous iliopsoas bleeding. Parallel to bypassing therapy, we started single-agent immunosuppression with prednisolone at 1.5mg/kg. FVIII:C "normalized" at 10.2% after four weeks. After five months, the inhibitor titre fell to <0.4BU with sustained remission after one year of follow-up. Conclusion: In mild HA, FVIII inhibitors may share characteristic features with FVIII autoantibodies commonly observed in acquired HA. Therefore, immunosuppressive therapy alone could be successful at least in a subset of patients.     

Does FVIII-activity increase with age in patients with haemophilia A and carriers of haemophilia A?

The retrospective cohort study surveys the influence of age, co-morbidity and laboratory values on FVIII-activity (FVIII:C) in patients with haemophilia A with (mild n = 48, moderate n = 10, severe n = 7 and carriers n = 23). Median observation was 19 years for patients with haemophilia A and 9,5 years for carriers. Results: FVIII:C levels collected from patients with mild haemophilia A displayed a significant median increase of 6.5% with proceeding age (p = 0.0013). Patients with moderate haemophilia A (and carriers of haemophilia A) showed a non significant median increase of 1.05% (carriers 8%). Eight patients showed FVIII:C levels at last blood withdrawal that indicated a change of severity from moderate to mild haemophilia A. A significant correlation was found between FVIII:C and VWF:RCo (p = 0.0203) and AFP (p < 0.0005). The correlation between FVIII:C and triglycerides and LDH was significant negative (p < 0.0005). No significant correlation could be found for FVIII:C and co-morbidity, fibrinogen, cholesterol and VWF:Ag.     

Experience with use of recombinant activated factor VII

Recombinant activated factor VII (rFVIIa) has recently been introduced for improving haemostasis in haemophiliac patients developing alloantibodies (inhibitors) to factor VIII (FVIII) or factor IX (FIX). We describe the successful management of haemorrhagia with rFVIIa in five different situations: an episode of surgical bleeding in a patient with haemophilia A and non-surgical haemorrhages in four patients with haemophilia A, acquired haemophilia, congenital severe FV defect and pseudo-acquired haemophilia, respectively. In each case, rFVIIa was effective and safe. There is no doubt that rFVIIa is useful in the therapeutic management of patients with antibodies to FVIII or FIX. However, the treatment is expensive and a cost-effectiveness analysis would be useful.     

Inhibitor development in two patients with mild haemophilia A – spontaneous disappearance and no recurrence of the inhibitor after re-challenge

Inhibitors against factor VIII (FVIII) complicate the treatment of patients with haemophilia. In mild haemophilia, the development of antibodies against FVIII is rare. However, the occurrence of an inhibitor in mild haemophilia changes the bleeding phenotype from mild to severe, and thus becomes a major clinical problem. We report on two patients with mild haemophilia A (FVIII level 8 and 27%, respectively), who have a missense mutation in exon 16 (G to A transition in codon 1773) and exon 22 (T to C transition in codon 2096), respectively. Both mutations have not been described in the Haemophilia A Mutation, Structure Test and Resource Site. Our patients developed high titer inhibitors following an intensive FVIII replacement therapy due to a muscle bleeding and after a polytrauma. During the presence of the inhibitor, AICC or FVIIa was successfully used as bypassing agent. In both patients the inhibitor disappeared spontaneously. Years after the development of the inhibitor, the patients again received FVIII concentrates. Reappearance of the inhibitor was not observed in either patient. The reported cases indicate that inhibitors in patients with mild haemophilia might be transient and disappear spontaneously. Therefore, the necessity of immune tolerance therapy, which is costly and strenuous for the patients, should be critically examined for each individual patient and a watch and wait strategy might be advisable.     

Immune tolerance induction with high-dose FVIII and pulsed intravenous immunoglobulin

The development of neutralizing allo-antibodies against factor VIII (FVIII) or FVIII inhibitors is a severe complication in the treatment of haemophilia A. About 25% of the children with severe haemophilia A develop FVIII inhibitors. Here we report on a boy with severe haemophilia A and intron 22 inversion of the FVIII gene who was diagnosed at ten months of age. After 16 exposure days to FVIII (81 days after initial exposure) he developed a FVIII inhibitor (maximum: 9.76 BU/ml). Therapy: We started immune tolerance induction (ITI) according to the Bonn protocol with high dose plasma derived FVIII concentrate (100 IU per kg body weight) twice daily. For additional inhibitor elimination treatment the patient received intravenous immunoglobulin (ivIg) at a dose of 1-2 g/kg body weight every 4 to 6 weeks. After start of treatment a rapid decline of the inhibitor level was observed, nevertheless low FVIII inhibitor levels persisted (<5 BU/ml). Furthermore, the FVIII half-life was still accelerated. However, after every course of ivIg the inhibitor level declined and FVIII half-life was prolonged. Currently, the FVIII half-life is approaching normal values after more than seven months of ITI duration. Conclusion: Additional application of immunoglobulin is beneficial for immune tolerance induction.     

Treatment of haemophilia A in Tunisia: efficacy and inhibitor study

Cryoprecipitate is the principal type of factor VIII (FVIII) concentrate used for treating haemophilia A in Tunisia. Allergic reactions, viral transmission, and inhibitor formation remain the most serious complications of FVIII therapy. The aims of the study presented here were to evaluate the efficacy of FVIII therapy, to investigate the inhibitor prevalence, and the factors which may affect inhibitor formation in our haemophilia A patients. Plasma samples were screened for FVIII inhibitors by the Bethesda method. 30 minutes FVIII recovery was also determined for each patient. In this prospective study, 18 previously treated haemophilia A patients, four with severe (FVIII concentration <2%) and 14 with moderate haemophilia, were closely followed up during administration of 223 FVIII concentrates (cryoprecipitate and/or fresh frozen plasma). The median age of the patients involved in the study was 13.5 years (range 5 to 53). Clinical response to FVIII was consistently good to excellent. In the majority of cases, actual and predicted FVIII recovery correlated' well. Adverse reactions were not observed. Five patients, aged less than 18 years and minimally treated (>36 FVIII exposure days), were found to have low titre FVIII inhibitors (<10 Bethesda units) at the end of the study. Inhibitor activity was detected in one patient with severe and in four patients with moderate haemophilia. In conclusion, FVIII therapy was effective, well tolerated, and low titre inhibitors identified did not preclude continued on demand FVIII therapy. Our study has also demonstrated that patients' age and treatment regimen do not affect inhibitor formation. Further studies are necessary to confirm these findings.     

NovoSeven: mode of action and use in acquired haemophilia

Recombinant activated factor VII (rFVIIa, ‘NovoSeven’) is indicated for the treatment of spontaneous and surgical bleeding in patients with haemophilia A or B with antibodies to factors VIII or IX (FVIII or FIX) worldwide, and in patients with acquired haemophilia in Europe. In vitro cell models have demonstrated that rFVIIa can bind to activated platelets and generate small amounts of Fxa, independent of the presence of tissue factor. The amount of platelet-surface Fxa formed increases with rising concentrations of FVIIa and, at levels of rFVII a that are effective in patients, sufficient platelet surface Fxa is generated partially to restore platelet surface thrombin generation. Acquired haemophilia is a rare but potentially life-threatening condition, caused by the autoimmune reduction of clotting factor levels as a result of the spontaneous development of auto-antibodies directed against the deficient factor. Bleeding into the skin or muscles is common in acquired haemophilia and the associated mortality rate is approximately 20%. rFVIIa has reported efficacy in the treatment of major bleeding episodes in patients with acquired haemophilia, which may be explained by its distinct mechanism of action that induces haemostasis at the site of injury, independent of the presence of FVIII or FIX. Also, the localisation of the action of rFVIIa at the site of injury may explain why it is well tolerated in these patients.     

NovoSeven: mode of action and use in acquired haemophilia

Recombinant activated factor VII (rFVIIa, 'NovoSeven') is indicated for the treatment of spontaneous and surgical bleeding in patients with haemophilia A or B with antibodies to factors VIII or IX (FVIII or FIX) worldwide, and in patients with acquired haemophilia in Europe. In vitro cell models have demonstrated that rFVIIa can bind to activated platelets and generate small amounts of Fxa, independent of the presence of tissue factor. The amount of platelet-surface Fxa formed increases with rising concentrations of FVIIa and, at levels of rFVII a that are effective in patients, sufficient platelet surface Fxa is generated partially to restore platelet surface thrombin generation. Acquired haemophilia is a rare but potentially life-threatening condition, caused by the autoimmune reduction of clotting factor levels as a result of the spontaneous development of auto-antibodies directed against the deficient factor. Bleeding into the skin or muscles is common in acquired haemophilia and the associated mortality rate is approximately 20%. rFVIIa has reported efficacy in the treatment of major bleeding episodes in patients with acquired haemophilia, which may be explained by its distinct mechanism of action that induces haemostasis at the site of injury, independent of the presence of FVIII or FIX. Also, the localisation of the action of rFVIIa at the site of injury may explain why it is well tolerated in these patients.     

Factor VIII (FVIII) gene mutations in 120 patients with hemophilia A: detection of 26 novel mutations and correlation with FVIII inhibitor development

BACKGROUND: As the publication of the sequence of the factor VIII gene (FVIII) in 1984, a large number of mutations that cause hemophilia A (HA) have been identified. Thanks to the advances in the detection of mutations, it is now possible to identify a putative FVIII sequence alteration in the vast majority of patients with HA.OBJECTIVES: Our main objective was to report on the spectrum of FVIII mutations and their distribution throughout the gene in 120 patients with HA. METHODS: Screening of FVIII mutations was performed using direct sequencing. Newly described missense mutations were further studied by molecular modeling. RESULTS: A total of 47 different HA causative FVIII mutations have been identified, 26 of which are described for the first time. These novel mutations include 14 missense and six nonsense mutations, two small deletions, one large deletion and three splice-site mutations. We further investigated the development of FVIII-specific inhibitors in all patients with HA. We found that four novel mutations (Ser882X, Tyr1786Ser, Ala2218Thr and a splice-site defect in intron 22) were associated with inhibitor development. CONCLUSION: These data extend our insight into the mechanisms by which novel amino acid substitutions may lead to HA, and how HA patient genotypes influence the risk of FVIII inhibitor development.     

Haemophilia A and haemophilia B. Are there relevant clinical differences?

Haemophilia B (HB) was described in 1952 as a single disease for the first time. In comparison to haemophilia A (HA) the bleeding tendency seemed to be less severe. The aim of this study was to investigate this hypothesis in all patients with HA and HB treated in the haemophilia care center of the Vivantes Klinikum. Patients, methods: All patients with severe HA and HB treated at the haemophilia care center were included. We evaluated the regimen of replacement therapy and factor concentrate consumption within the last 5 years (1/2004 to 12/2008). Intracerebral bleeds were analysed over the whole life span of the included patients. Results: 111/181 patients with HA had the severe form and 12/34 patients severe HB. 4/12 patients with severe HB had a history of intracerebral bleeding in comparison to 5/111 patients with severe HA. 2/8 adult patients with severe HB used a prophylactic treatment with factor concentrates (mean consumption 1289 IU factor IX/kg BW/year) in contrast to 60/95 adult patients with HA (mean consumption 2109 IU factor VIII /kg BW/year). Conclusion: The data suggest a milder bleeding type of patients with severe HB in comparison to patients with severe HA but may be patients with severe HB are at higher risk for intracerebral bleeds.     

A systematic overview of the first pasteurised VWF/FVIII medicinal product, Haemate P/ Humate -P: history and clinical performance

Patients with von Willebrand disease (VWD) and haemophilia A (HA) lack, to varying degrees, the von Willebrand factor (VWF) and coagulation factor VIII (FVIII) that are critical for normal haemostasis. These conditions in turn make patients prone to uncontrolled bleeding. Historically, patients with severe forms of VWD or HA were crippled before adulthood and their life expectancy was significantly reduced. Over the past decades, specific coagulation factor replacement therapies including Haemate P, have been developed to help patients achieve and maintain normal haemostasis. Haemate P is a human, plasma-derived VWF/FVIII medicinal product, which was first licensed in Germany in 1981 for the treatment of HA-associated bleeding. It has since then come to be accepted as the gold standard for both the treatment and prophylaxis of bleeding in VWD, especially in cases where desmopressin [1-deamino-8-D-arginine vasopressin (DDAVP)] has been ineffective. Haemate P was the first effectively virus-inactivated (pasteurisation: 60 degrees C for 10 h in aqueous solution) FVIII product, whereby the risk of potentially threatening infective complications of plasma-derived products was reduced. Haemate P was also shown to have a VWF multimer profile remarkably close to that of normal plasma. This bibliographic review presents previously unpublished clinical data of Haemate P, based upon internal clinical study reports of the proprietor, CSL Behring, in addition to data already presented in other publications. The data demonstrate a predictable and well-characterised pharmacokinetic profile, and a proven record of short- and long-term safety, while effectively correcting the haemostatic defects in VWD and HA. Recently available data have also shown Haemate P to be of haemostatic value in exceptional clinical circumstances including surgical interventions. By virtue of its plasma-derived combination of VWF and FVIII, in addition to its high VWF:FVIII content ratio (2.4:1), Haemate P is also associated with successful immune tolerance induction in those patients developing inhibitor antibodies. Although the theoretical risk of thromboembolic complications does exist while receiving Haemate P, as it does with any FVIII replacement therapy, the incidence of such complications has remained notably low. Given the robust data that have accumulated for the use of Haemate P, dosing recommendations are also described in this review; the recommendations are tailored to patient-specific contexts including baseline VWF and FVIII levels in plasma and the type of surgical intervention being undertaken. A wide variety of studies have also provided data on paediatric and geriatric populations, all of which have suggested that Haemate P can be safely and effectively used in a wide variety of clinical circumstances.     

Lentivirus-mediated platelet-derived factor VIII gene therapy in murine haemophilia A

BACKGROUND: Previous studies from our laboratory have demonstrated that lineage-targeted synthesis of factor VIII (FVIII) under the direction of the platelet-specific integrin alphaIIb gene promoter (2bF8) can correct the murine haemophilia A phenotype even in the presence of high titer inhibitory antibodies in a transgenic mouse model. OBJECTIVE: In this study, we assessed the efficacy of using a genetic therapy approach to correct haemophilia A in FVIII-deficient (FVIII(null)) mice by transplantation of bone marrow (BM) transduced with a lentivirus (LV)-based gene transfer cassette encoding 2bF8. RESULTS: Functional FVIII activity (FVIII:C) was detected in platelet lysates from treated mice and the levels were similar to 2bF8 heterozygous transgenic mice. Mice transplanted with 2bF8 LV-transduced BM survived tail clipping and we did not detected inhibitory or non-inhibitory FVIII antibodies over the period of this study (11 months). Furthermore, BM transferred from the primary transplant recipients into FVIII(null) secondary recipients demonstrated sustained platelet-FVIII expression leading to correction of the haemophilia A phenotype showing that gene transfer occurred within long-term repopulating haematopoietic stem cells. CONCLUSIONS: These results demonstrate that ectopic expression of FVIII in platelets by lentivirus-mediated bone marrow transduction/transplantation may be a promising strategy for gene therapy of haemophilia A in humans.     

Haemophilia A therapy of adults. Actual treatment situation in a haemophilia centre

In a retrospective study from a single treatment centre (Centre for Haemostaseology Muenster) the current treatment conditions of patients with severe haemophilia A (FVIII:C <1%) at the age of ≥ 16 years are described. Data were extracted from paper based diaries of patients in home treatment (n = 70). Results: A progressive preference towards prophylactic treatment compared to on demand therapy is observed. On average 2.4 injections per week (mean: 1750 IU FVIII per injection) are used in the prophylactic regimen. The consumption of FVIII concentrates is approximately fivefold increased compared to on demand therapy (average 0.5 injections per week). Meanwhile, recombinant FVIII concentrates have become widely accepted in all age groups, they show a proportion of 60% in the clinical practice of the study population.     

Molecular analysis of FVIII gene in severe HA patients of Costa Rica

Haemophilia A (HA) is X-chromosome linked bleeding disorders caused by deficiency of the coagulation factor VIII (FVIII). It is caused by FVIII gene intron 22 inversion (Inv22) in approximately 45% and by intron 1 inversion (Inv1) in 5% of the patients. Both inversions occur as a result of intrachromosomal recombination between homologous regions, in intron 1 or 22 and their extragenic copy located telomeric to the FVIII gene. The aim of this study was to analyze the presence of these mutations in 25 HA Costa Rican families. Patients, methods: We studied 34 HA patients and 110 unrelated obligate members and possible carriers for the presence of Inv22or Inv1. Standard analyses of the factor VIII gene were used incl. Southern blot and long-range polymerase chain reaction for inversion analysis. Results: We found altered Inv22 restriction profiles in 21 patients and 37 carriers. It was found type 1 and type 2 of the inversion of Inv22. During the screening for Inv1 among the HA patient, who were Inv22 negative, we did not found this mutation. Discussion: Our data highlight the importance of the analysis of Inv22 for their association with development of inhibitors in the HA patients and we are continuous searching of Inv1 mutation. This knowledge represents a step for genetic counseling and prevention of the inhibitor development.     

Rituximab in the treatment of acquired haemophilia A in a patient with polymyalgia rheumatica

Acquired hemophilia A is a rare but potentially life-threatening bleeding disorder. It is caused by the development of autoantibodies directed against coagulation factor VIII in adults or elderly patients, who do not have a personal or family history of bleeding. Case: A man (age: 76 years) on prednisone and leflunomide for polymyalgia rheumatica developed spontaneous severe haematomas. The patient was diagnosed with acquired factor VIII deficiency (FVIII activity 1.2%, FVIII inhibitor 31.7 BU). Due to the active bleeding diathesis, treatment was administered with activated prothrombin complex concentrates (FEIBA®, Baxter). Immunosuppressive treatment with a combination of oral prednisone (1 mg/kg daily) and cyclophosphamide (1,5 mg/kg daily) was administered to reduce the FVIII inhibitor. However, after two weeks of treatment, FVIII was only 3% and no clinical improvement was observed. Treatment with the anti CD20 monoclonal antibody rituximab intravenously at 375 mg/m2 once weekly for four consecutive weeks was started. The patient showed rapid clinical improvement following rituximab treatment. He achieved a complete remission defined as return to normal FVIII activity and undetectable FVIII inhibitor titer. After a follow-up of six months no relapse occurred. Conclusion: Rituximab appears an effective and well-tolerated treatment for patients with acquired haemophilia.     

Pharmacotherapy of haemophilia A

INTRODUCTION: Haemophilia A is due to factor VIII (FVIII) deficiency. The main treatment is replacement therapy with FVIII concentrates. However, these concentrates carried a high risk of blood-borne viral infections and still have a high risk of inducing anti-FVIII inhibitors. AREAS COVERED: An overview of products available and therapeutic options for haemophilia A management in order to help in decision making. A literature search using Medline with the keywords: 'haemophilia', 'factor VIII', 'therapy', 'inhibitor', 'concentrate', 'bleeding', 'prophylaxis', 'on demand', 'plasma-derived', 'recombinant', 'coagulation factors', 'immunotolerance' was performed. The years 1960 - 2010 are included. EXPERT OPINION: Progress in management of patients with haemophilia A has allowed increased life expectancy and quality of life. There is evidence that prophylaxis prevents or, at least, slows down arthropathy development when started early in childhood. FVIII concentrates have achieved high levels of blood-borne pathogen safety. However, treatment is frequently complicated by development of FVIII-neutralizing inhibitors, which prevent control of bleeding and predispose to a high morbidity and mortality risk. Bypassing agents are effective in bleeding treatment in a high percentage of cases. Prophylaxis with bypassing agents and their use in combination are offering opportunities in management of inhibitor patients. More evidence is necessary to understand how to prevent and manage this complication.