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Haemophilia B (haemophilia + b)
Kinds of Haemophilia B Selected AbstractsGalectin 3-binding protein is a potential contaminant of recombinantly produced factor IXHAEMOPHILIA, Issue 6 2007M. BLOSTEIN Summary., Haemophilia B, or factor IX (FIX) deficiency, represents 15% of the hereditary haemophilias. The serious morbidity from the transmission of infectious agents in plasma-derived material has mandated a need for the production of recombinant product. The rate-limiting step for the production of recombinant FIX is ,-carboxylation, a post-translational modification carried out only in mammalian cells. To test the carboxylation efficiency of recombinantly produced FIX in vitro and to improve the isolation of the pure active product, we produced FIX in a transfected human cell line (293 human embryonic kidney cells) and isolated material by immunoaffinity chromatography followed by hydroxyapatite chromatography. Unexpectedly, during hydroxyapatite chromatography, we discovered that purified FIX was contaminated by a heretofore unknown protein. Further analysis by mass spectrometry (MS) sequencing revealed this protein to be galectin-3-binding protein (G3BP). The above results raise an important note of caution regarding the production of recombinant FIX and, indeed, other proteins produced recombinantly in mammalian cells. [source] Domiciliary application of CryoCuff in severe haemophilia: qualitative questionnaire and clinical auditHAEMOPHILIA, Issue 4 2008A. I. D'YOUNG Abstract., The acute management of haemophilic bleeding episodesin the home setting is based on the concept of immediate factor replacement therapy and the PRICE regime , an acronym representing the concepts of Protection, Rest, Ice, Compression and Elevation [1,2]. Integral to this regime is the application of cold therapy, and yet little is known regarding the safe periods of application, or the relative safety of cryotherapy devices such as the CryoCuffÔ when used in the home setting by patients suffering from severe haemophilia and related bleeding disorders. This study examines the subjective patient response to the application of the CryoCuffÔ device in the home setting in terms of the effect on pain, joint swelling and the return to ,pre-bleed status' of the knee, ankle or elbow in patients with severe haemophilia A/B or type III von Willebrand's disease (VWD) immediately following haemarthrosis, and any potential adverse effects related to the device or recommended duration of application as stated in the PRICE guideline (Fig. 1). Twelve patients, either with severe haemophilia A/B or with VWD were recruited and asked to use the CryoCuffÔ device as part of the PRICE regime immediately following the onset of knee-, ankle- or elbow bleeds for the next one year. Each subject was then sent a qualitative questionnaire to determine subjective responses to the device. All patients reported that the application protocol was easy to follow, they were able to apply the device as per the PRICE regime and they were able to tolerate it for the recommended period. Whereas, all the patients felt that the device had a significant impact on alleviation of pain and return to pre-bleed status, 78% of the patients felt that the device led to a significant reduction in swelling around the affected joint. There was no conclusive evidence that the device resulted in any reduction in the amount of factor used to treat the acute bleeding episode, however, no patients reported any perceived delay in achieving haemostasis or required extra factor replacement therapy consequent to the usage of the device. No other adverse effects were reported by participants in this study. Figure 1. ,The qualitative participant questionnaire, given following 1 year of unsupervised use in the home setting immediately following the onset of the symptoms of haemarthroses. [source] Variability in bleeding phenotype in Amish carriers of haemophilia B with the 31008 C,T mutationHAEMOPHILIA, Issue 1 2009A. SHARATHKUMAR Summary., The aim of this study was to characterize the variability of bleeding phenotype and its association with plasma factor IX coagulant activity (FIX:C) in haemophilia B carriers in a large Amish pedigree with a unifying genetic mutation, C-to-T transition at base 31008 of the factor IX gene (Xq27.1,27.2). A cross-sectional survey of haemophilia B carriers included a multiple choice questionnaire evaluating symptoms of mucocutaneous bleeding, joint bleeding and bleeding after haemostatic stress [menstruation, postpartum haemorrhage (PPH), dental extractions and invasive surgeries]. Severity of bleeding was graded as 0 to 4, 0 being no bleeding whereas 4 being severe bleeding. Association between total bleeding scores and the FIX:C was evaluated. Sixty-four haemophilia B carriers participated in this study. Median age: 18 years (range 1,70 years); median bleeding score: 1 (range 0,8). Besides PPH, isolated symptoms of bruising, epistaxis, menorrhagia and postsurgical bleeding including dental extraction were not associated with lower FIX:C. Bleeding score ,3 was associated with involvement of at least two bleeding sites and a lower mean FIX:C of 42 ± 10.3% (95% CI 36.4,47.7) while a score >3 had involvement of ,2 sites and higher mean FIX:C of 54.9 ± 21.5% (95% CI 49,61), P = 0.005. Subcutaneous haematoma formation and bleeding after haemostatic stress requiring treatment were associated with bleeding scores ,3. Phenotypic variability existed among the carriers of haemophilia B who belonged to a single pedigree carrying a single unifying mutation. The utility of bleeding scores to define bleeding phenotype precisely in haemophilia B carriers needs further evaluation. [source] Central venous access devices for paediatric patients with haemophilia: a single-institution experienceHAEMOPHILIA, Issue 1 2009R. TITAPIWATANAKUN Summary., Use of a central venous access device (CVAD) can facilitate early introduction of home-based infusion of factor concentrate for long-term prophylaxis or immune tolerance therapy in children with bleeding disorders. The aim was to review outcomes associated with use of CVAD. Retrospective review of paediatric patients with bleeding disorders was observed at the Mayo Clinic Comprehensive Hemophilia Center. Thirty-seven CVAD were placed in 18 patients (haemophilia A [n = 15], type 3 von Willebrand disease [n = 2] and haemophilia B [n = 1]). Follow-up was for 45 952 CVAD days, and median time that CVAD remained in place was 1361 days per device. Factor VIII (FVIII) inhibitors were present in 4 of the 15 patients. Ten CVAD-related infections occurred (median, 672 days; range, 72,1941 days), of which six were in one patient with FVIII inhibitors. Overall infection rate was 0.22 (95% confidence interval [CI], 0.10,0.40) per 1000 CVAD days, with 0.11 infections in patients without FVIII inhibitors compared with a pooled incidence of 0.66 (95% CI, 0.44,0.97) reported in the literature. Indications for removal of 27 CVAD were blockage, change to peripheral venous access, catheter displacement, infection, leak in the port septum, short catheter and skin erosion. No clinically apparent thrombosis or sequelae of thrombosis were observed. Infection is the most common complication associated with CVAD use and is increased in patients who have inhibitors. The low rate of clinically apparent thrombosis reflects our practice of not screening for thrombosis. The low infection rate reflects our practice of using and reinforcing the aseptic technique. [source] Influence of source of phospholipids for APTT-based factor IX assays and potential consequences for the diagnosis of mild haemophilia BHAEMOPHILIA, Issue 1 2009C. POUPLARD First page of article [source] Influence of factor IX on overall plasma coagulability and fibrinolytic potential as measured by global assay: monitoring in haemophilia BHAEMOPHILIA, Issue 1 2008N. A. GOLDENBERG Summary., We sought to determine the influence of factor IX (FIX) deficiency upon overall coagulative and fibrinolytic capacities in plasma using the clot formation and lysis (CloFAL) assay, and to investigate the role of this global assay as an adjunctive monitoring tool in haemophilia B. CloFAL assay parameters were measured in vitro in platelet-poor plasma in relation to FIX activity and antigen (FIX:Ag), and were determined ex vivo among FIX-deficient patients (n = 41) in comparison to healthy individuals (n = 48). Supplementation of FIX-deficient plasma with FIX in vitro demonstrated a non-linear concentration dependence of FIX upon overall plasma coagulability. Ex vivo, coagulability was significantly decreased in FIX-deficient vs. healthy subjects among adults [median coagulation index (CI): 4% vs. 104% respectively; P < 0.001] and children (median CI: 9% vs. 63%; P < 0.001). Fibrinolytic capacity was increased in adult FIX-deficient vs. healthy subjects (median fibrinolytic index: 216% vs. 125%, respectively, P < 0.001), and was supported by a trend in shortened euglobulin lysis time (ELT). Severe haemophilia B patients showed heterogeneity in aberrant CloFAL assay waveforms, influenced partly by FIX:Ag levels. Patients with relatively preserved FIX:Ag (i.e. dysfunctional FIX) exhibited a shorter time to maximal amplitude in clot formation than those with type I deficiency. During patient treatment monitoring, markedly hypocoagulable CloFAL assay waveforms normalized following 100% correction with infused FIX. The CloFAL global assay detects FIX deficiency, demonstrates differences in coagulability between dysfunctional FIX and type I deficiency, and appears useful as an adjunctive test to routine FIX measurement in monitoring haemophilia B treatment. [source] Reformulated BeneFix®: efficacy and safety in previously treated patients with moderately severe to severe haemophilia BHAEMOPHILIA, Issue 3 2007T. LAMBERT Summary. BeneFix®, the only recombinant factor IX (FIX), has been reformulated. The reformulation involves a change in diluent and allows for more concentrated infusions of recombinant FIX. A double-blind, randomized, pharmacokinetic (PK) crossover study demonstrated that reformulated BeneFix was bioequivalent to original BeneFix and follow-up PK evaluation after 6 months of treatment demonstrated the PK stability of reformulated BeneFix after multiple exposures. Favourable efficacy and safety profiles, consistent with those already well-established for original BeneFix, were observed: 81.1% of haemorrhages resolved with only a single infusion; 85.3% of initial treatment response ratings were Excellent or Good; more than half of the subjects using reformulated BeneFix for routine prophylaxis (11 of 17, 64.7%) had no spontaneous haemorrhages during their 6,12 month course of prophylactic treatment, with an overall spontaneous bleeding rate of 0.72 year,1; and for the single surgical procedure (knee washing), treatment was rated Useful. In addition, there was no FIX inhibitor development, allergic-type manifestations, or thrombogenic complications with more than 1100 infusions (nearly 5.2 million IUs) administered in this trial. All efficacy and safety outcomes from this study were achieved with more concentrated recombinant protein infusions than that possible with original BeneFix, and utilization of the 2000 IU per vial dosage strength, newly introduced with the reformulated product, was high (>62%). The reformulation of BeneFix allows smaller delivery volumes and an increased choice of dosage strengths without altering the PK properties (including incremental recovery and half-life) or the established efficacy and safety profile of recombinant FIX. [source] Cyclosporin A can achieve immune tolerance in a patient with severe haemophilia B and refractory inhibitorsHAEMOPHILIA, Issue 1 2007D. C. A. CROSS Summary., Immune tolerance induction (ITI) is described in a patient with severe haemophilia B complicated by the presence of an inhibitor. A number of ITI regimes were attempted without success and the patient suffered from frequent relapses and bleeding episodes. Successful ITI was achieved with the additional use of cyclosporin A. The patient developed nephrotic syndrome although had a negative Bethesda titre at this time. When cyclosporin A therapy was ceased, the inhibitor titre rose and the patient suffered again from bleeding episodes. Cyclosporin A was reintroduced at a lower dose. The patient has now received cyclosporin A for 10 years, during which time he has relapsed three times for short periods (2 weeks). He is also on prophylaxis with factor IX three times a week with preinfusion levels >1% and without bleeding. [source] Insight into molecular changes of the FIX protein in a series of Italian patients with haemophilia BHAEMOPHILIA, Issue 3 2006M. P. BICOCCHI Summary., Deficiency or dysfunction of factor IX FIX leads to haemophilia B (HB), an X-linked, recessive, bleeding disorder. On a molecular basis, HB is due to a heterogeneous spectrum of mutations spread throughout the F9 gene. In several instances, a cause-effect relation has been elucidated, in others predicted possibilities have been offered by crystallography inspection and by software-constructed models of the protein. The aim of this study was to contribute to the understanding of HB molecular pathology. The F9 missense mutations we identified in 21 unrelated Italian HB patients by direct sequencing of the whole F9 coding regions were inspected for the causative effect they provoked on the ensuing transcript, and on the protein structure. Each alteration was studied in order to: (i) characterize the defect on the basis of the nature of the mutation; (ii) identify the predicted defect that is induced in the gene and (iii) speculate about the potential, detrimental effects which upset the protein functionality through an idealized FIX model. The resulting data may further contribute to the comprehension of the mechanisms underlying the disease. [source] Helicobacter pylori infection in patients with haemophilia in Poland: prevalence and risk of upper gastrointestinal bleedingHAEMOPHILIA, Issue 4 2005A. B. Szczepanik Summary., Infection with Helicobacter pylori is the main aetiological factor for erosive gastritis and duodenal or gastric peptic ulcers often complicated with life-threatening bleeding in patients with coagulation disorders. The aim of this prospective study was to evaluate the prevalence of Helicobacter pylori infection in haemophilia patients, and to assess the risk of gastrointestinal bleeding associated with this infection. From 2000 to 2002, 146 patients with haemophilia (129, haemophilia A; 13, haemophilia B), mean age, 39.9 years (±7.3), were investigated for H. pylori infection using IgG and IgA latex serological test. The control group included 100 men with no coagulation disorders, mean age, 40.9 years (±9.2). For 72 (49.3%) patients with haemophilia and 39 controls (39.0%) serological tests were positive indicating the presence of H. pylori infection (P =0.1112). A history of gastrointestinal bleeding was reported in 46 patients (31.5%) with haemophilia and in two control group patients (2.0%) (P < 0.0001). Gastrointestinal bleeding was significantly more frequent in patients with haemophilia infected with H. pylori (33/46; 71.7%) than in patients with no H. pylori infection (13/46; 28.3%; P = 0.0002). In conclusion, the prevalence of H. pylori infection in haemophilic patients in Poland is comparable with that in patients with no coagulation disorders. Helicobacter pylori infection is a risk factor for duodenal and gastric ulcer bleeding in haemophilia patients. In view of the high frequency of upper gastrointestinal bleeding associated with H. pylori infection, we believe that screening and eradication therapy are appropriate in haemophilia patients. [source] Changing pattern of care of boys with haemophilia in western European centresHAEMOPHILIA, Issue 2 2005H. Chambost Summary., Haemophilia management is not uniform among countries, even within western Europe, that have close economic, social and cultural relationship. The European Paediatric Network PedNet aims to share experiences in the field of the care of boys with haemophilia. In 1998, a PedNet survey has shown significant disparities in 20 centres from 16 countries, particularly as regards the implementation of prophylaxis regimen. This survey has been updated in 2003 to describe the current status of haemophilia management in 22 centres and the changing pattern of care of boys with severe haemophilia in western Europe. Regular, continuous long-term prophylaxis is provided in all PedNet centres, more than 50% and 80,100% of boys being treated this way in 20/22 and 15/22 centres respectively. Twenty of the 22 centres (91%) recommend continuous prophylaxis (primary or secondary A) for a new patient. The use of recombinant factor VIII concentrates was already widespread in 1998 and a further expansion of recombinant products has been observed over the last 5 years. Recombinant FVIII is now used exclusively in nine centres and for more than 80% of boys with haemophilia A in nine other centres. The use of recombinant and plasma derived FIX is more balanced: among 18 centres where boys with haemophilia B are treated, 14 use recombinant FIX, and nine administer it to a majority of patients. Other modifications of practice have been stressed in this survey, such as more targeted use of central venous devices in the youngest boys and more extensive characterisation of genetic mutations. [source] A 6-year follow-up of dosing, coagulation factor levels and bleedings in relation to joint status in the prophylactic treatment of haemophiliaHAEMOPHILIA, Issue 6 2004J. Ahnström Summary., The primary aim of this study was to investigate the possible relationship between coagulation factor level and bleeding frequency during prophylactic treatment of haemophilia after stratification of the patients according to joint scores. The secondary aim was to obtain a systematic overview of the doses of coagulation factors prescribed for prophylaxis at the Malmö haemophilia treatment centre during a 6-year period. A retrospective survey of medical records for the years 1997,2002 and pharmacokinetic study results from the 1990s was complemented by collection of blood samples for coagulation factor assay when needed. Information on the dosing and plasma levels of factor VIII or factor IX, joint scores and incidence of bleedings (joint bleeds and ,other bleeds') was compiled. The patients were stratified by age (0,6, 7,12, 13,18, 19,36 and >36 years) and joint score (0, 1,6 and >6). Individual pharmacokinetic parameters of plasma coagulation factor activities (FVIII:C and FIX:C) were estimated. Trough levels during the treatment were calculated, as well as the number of hours per week of treatment during which plasma FVIII:C/FIX:C fell below a 1, 2 or 3% target level. Fifty-one patients with haemophilia A (two moderate, 49 severe) and 13 with haemophilia B (all severe) were included, yielding data for 364 patient-years of treatment. There was a wide range of dosing schedules, the most common ones being three times a week or every other day for FVIII and twice a week or every third day for FIX. The overall relationship between FVIII:C/FIX:C levels and incidence of joint bleeding was very weak, even after stratification of the patients according to joint score. There was no relationship between coagulation factor level and incidence of other bleeds. In this cohort of patients on high-dose prophylactic treatment, dosing was based more on clinical outcome in terms of bleeding frequency than on the aim to maintain a 1% target level of FVIII:C/FIX:C. Some patients did not bleed in spite of a trough level of <1% and others did in spite of trough levels >3%. The practical implication of our findings is that dosing in prophylactic treatment of haemophilia should be individualized. Thus, proposed standard regimens should be implemented only after careful clinical consideration, with a high readiness for re-assessment and individual dose tailoring. [source] Inherited coagulation disorders in southern IranHAEMOPHILIA, Issue 6 2002M. Karimi Summary., A comprehensive survey concerning the Shiraz Hemophilia Society and the associated haemophilia treatment centre was undertaken in April 2002 to collect data on demographics, signs and symptoms in the southern Iranian population with haemophilia and allied disorders. The total number of patients with coagulation disorders was 367. Haemophilia A (factor [F] VIII deficiency) was found in 271, 39 had haemophilia B (FIX deficiency) and 24 had von Willebrand disease. The rare coagulation disorders (n = 33) included 11 patients with FX deficiency; 10 with FVII; six with FXIII; two with afibrinogenaemia; two with FXI; one with combined FVIII and FV; and one with combined FVII, FVIII and FIX deficiency. The prevalence was 6.64 per 100 000 inhabitants. The most common symptoms were haemarthrosis, haematomas and epistaxis. None of the patients were human immunodeficiency virus positive but 47 (15%) were hepatitis C virus positive and two (0.7%) were hepatitis B positive, so that the rate of transfusion-transmitted infections was lower compared with other populations. [source] Orthopaedic surgery in severe bleeding disorders: a low-volume, high-cost procedureHAEMOPHILIA, Issue 6 2002V. Mishra Summary. As more and more nations are scrutinizing their health care costs, attention has been focused on high-cost low-density disease. Assessment of actual total cost of care for haemophilia and its positive outcome becomes essential to justify support for these patients. In this study, we assessed hospital cost and diagnosis-related group (DRG) reimbursement for patients undergoing elective orthopaedic surgical procedures from May 1999 to December 1999. Hospital cost was assessed by a prospective microcost-analysis method. To identify real hospital costs, we performed registration of preoperative phase, operative phase and 1-year follow-up costs. Hospital cost included personnel costs and costs for clinical and laboratory procedures, blood products, prosthetic implants, coagulation factor concentrates and drugs. These data were compared with hospital DRG reimbursement. We included nine consecutive patients, with a mean age 38 years (19,54 years) who had had 10 major orthopaedic surgical procedures performed during the study period. Six patients had haemophilia A, two had haemophilia B and one had factor VII deficiency. Data analysis showed a mean cost of US$ 54 201 (range US$ 25 795,105 479; 1US$ = 8.5 NOK). The average actual hospital revenue (50% DRG reimbursement + income related to length of stay) was $4730 (range $ 1 308,13 601). Our study confirms that orthopaedic surgery in patients with severe bleeding disorders puts the hospital to a considerable expense. Activity-based financing, as used in Norway, does not provide a proper reimbursement for this part of the haemophilia care. [source] Bacterial endocarditis in a child with haemophilia B: risks of central venous cathetersHAEMOPHILIA, Issue 5 2001D. K. Hothi The use of central venous catheters may be complicated by thrombosis and infection. We report a case of a needle-phobic 5-year-old boy with factor IX deficiency, in whom a portacath was inserted owing to poor compliance with prophylactic treatment. Within a week, he developed a Staphylococcus aureus line infection that was treated with a 2-week course of intravenous antibiotics. One month later he presented with nonspecific symptoms and blood cultures again grew S. aureus. An echocardiogram revealed a large vegetation adherent to the tricuspid valve, confirming the diagnosis of bacterial endocarditis. His clinical course was further complicated by the development of pulmonary emboli. Medical treatment with intravenous antibiotics led to a successful resolution of the endocarditis and pulmonary emboli with a favourable long-term outcome. [source] Recombinant factor IX (BeneFix®) by adjusted continuous infusion: a study of stability, sterility and clinical experienceHAEMOPHILIA, Issue 2 2001P. Chowdary The safety and efficacy of adjusted continuous infusion (CI) of recombinant factor IX (FIX; BeneFix®) was assessed in vitro and in a clinical study. BeneFix® was reconstituted at 100 IU mL,1 with or without unfractionated heparin (4 U mL,1) and stored at either 4 °C or room temperature. Reconstituted BeneFix® retained at least 90% activity over 14 days if stored at 4 °C but stability was reduced at room temperature. BeneFix® reconstituted in a sterile pharmacy was free of bacterial contamination. Six patients with haemophilia B received seven CIs of BeneFix® to cover routine surgery and severe bleeding episodes. The CIs lasted between 3 and 10 days. In all cases, haemostasis was excellent and the desired therapeutic FIX level was easily maintained. No thrombotic episodes or inhibitor development occurred but two patients developed thrombophlebitis at the infusion site when heparin was not added to the infusion. BeneFix® is not currently licensed for CI and we suggest that studies to enable licensing should be established as soon as possible. [source] Influence of factor VIII:C and factor IX activity in plasmas of haemophilic dogs on the activated partial thromboplastin time measured with two commercial reagentsHAEMOPHILIA, Issue 3 2000R. Mischke The present study is based on 145 plasma samples with a reduced activity of factor VIII:C (range: 0.009,0.62 IU mL,1) and 28 samples with a reduced factor IX activity (range: 0.035,0.55 IU mL,1). The samples were collected from dogs with haemophilia A (n=22) or haemophilia B (n=3), some of these during substitution therapy. For all samples the activated partial thromboplastin time (APTT) was measured with two commercial reagents containing kaolin as a contact activator. In each case, the deficiency of factor VIII:C or IX was reflected in abnormal results of the APTT. This was true for both reagents. A significant correlation (P < 0.001) was found between factor VIII:C activity and APTT (reagent 1, Pathromtin®; Spearman's rank correlation coefficient, rS=,0.731, reagent 2, PTT-Reagenz; rS=,0.875) as well as between factor IX activity and APTT (reagent 1, rS=,0.819; reagent 2, rS=,0.955]. In each case, the relationship between coagulation factor activity and APTT could be proven most precisely by geometric regression. The results of this study illustrate the applicability of commercial APTT test kits as a sensitive screening test of factor VIII:C and IX deficiencies in canine plasma. [source] Management of third molar removal with a single dose of recombinant Factor IX (BeneFIX) and local measures in severe haemophilia BAUSTRALIAN DENTAL JOURNAL, Issue 3 2010ID Hewson Abstract Background:, Patients with inherited bleeding disorders have historically had factor cover for oral surgery. Factor support is expensive, time consuming and places the patient at a potential risk of blood-borne diseases. This case describes the use of a significant reduction in factor support for a severe haemophilia B patient having third molars surgically removed. Methods:, Local measures were used after a single preoperative dose of Factor IX to obtain good postoperative haemostasis. Results:, Excellent haemostasis was achieved using local measures of 5% tranexamic acid solution, Surgicel® and Monocryl® sutures after a single preoperative dose of Factor IX. Conclusions:, Oral surgery may be performed on patients with inherited bleeding disorders using minimal factors and local haemostatic measures. A study of this patient population has commenced at The Alfred Hospital. [source] Molecular pathology of haemophilia B in Turkish patients: identification of a large deletion and 33 independent point mutationsBRITISH JOURNAL OF HAEMATOLOGY, Issue 4 2003U. Venüs Onay Summary. Heterogeneous mutations in the coagulation factor IX (FIX) gene result in a bleeding tendency known as haemophilia B. The haemophilia B mutation database has a total of 2353 patient entries, including 10 of the estimated 1000 Turkish patients. In this study, a more comprehensive analysis of the molecular pathology of haemophilia B in Turkey revealed one large deletion and 33 point mutations in the FIX gene of 34 unrelated patients. Haplotype analysis using six polymorphic sites showed that the mutations identified in a total of 45 patients occurred on 13 different haplotypes and that each mutation was family specific. [source] Single nucleotide polymorphisms of the factor IX gene for linkage analysis in the southern Chinese populationBRITISH JOURNAL OF HAEMATOLOGY, Issue 2 2000Vivian Chan Carrier detection and prenatal testing for haemophilia B in Oriental populations have been hampered by the lack of informative markers within the factor IX (FIX) gene. We detected a T/C nucleotide variation at nucleotide 32770 in the poly-A region of the FIX gene in the mother of a haemophilia B child. Analysis of 139 unrelated alleles revealed a heterozygosity rate of 0·193, thus offering an additional marker for linkage analysis. Together with two other polymorphic sites (5,MseI and 3,HhaI) found in Chinese and Thai populations, these polymorphisms were useful in 66% of the families studied. [source] | ||||||||||