Hemophilia B

Currently, molecular diagnosis of haemophilia A and B (HA and HB) highlights the excess risk-inhibitor development associated with specific mutations, and enables carrier testing of female relatives and prenatal or preimplantation genetic diagnosis. Molecular testing for HA also helps distinguish it from von Willebrand disease (VWD). Next-generation sequencing (NGS) allows simultaneous investigation of several complete genes, even though they may span very extensive regions. This study aimed to evaluate the usefulness of a molecular algorithm employing an NGS approach for sequencing the complete F8, F9 and VWF genes. The proposed algorithm includes the detection of inversions of introns 1 and 22, an NGS custom panel (the entire F8, F9 and VWF genes), and multiplex ligation-dependent probe amplification (MLPA) analysis. A total of 102 samples (97 FVIII- and FIX-deficient patients, and five female carriers) were studied. IVS-22 screening identified 11 out of 20 severe HA patients and ...

Mutations in Factor IX gene (F9) cause X-linked recessive bleeding disorder hemophilia B. Here, we characterized molecular events in nine North Indian hemophiliac families identifying four missense mutations (three novel), two nonsense mutations, and a deletion. We have also captured the mutational spectrum of this disease in India based on available reports and established their genotype/phenotype relationships. Indian F9 mutations data indicate the absence of an important germline mutagen in the Indian subcontinent over the last century, and are consistent with previously made conclusions that universal, presumably endogenous factors are predominant in the causation of the spontaneous mutations in F9. We also analyzed the distribution of Ala194Thr polymorphism in 1231 Asian Indians and have established that Ala variant is far more frequent and can certainly be exploited for carrier detection, contrary to earlier reports. © 2007 Wiley-Liss, Inc

An unusual cause of obstructive sleep apnea in a boy with hemophilia B who was urgently intubated during the night because of suspected bleeding into the airway is analysed. The cause of airway obstruction was a floating papilloma hanging from false cord. At inspirium the tumor was moving immediately above the vocal cords. This was manifested during sleep by noisy snoring and numerous apneic pauses. When the child was awake he had no respiratory problems. After the tumor was removed, the boy breathed freely during sleep. However, the papillomas recur in various parts of the larynx and repeated surgical treatment by factor IX replacement: therapy is necessary.

The primary goal of hemophilia treatment and management is the prevention of painful, disabling, and costly joint arthropathy that results from its characteristic bleeding into joints and muscles. Prophylactic treatment with clotting-factor concentrates has been shown to prevent hemophilic arthropathy and is, therefore, the standard of care for hemophilia A and B. Data has demonstrated the clinical efficacy and overall benefits of prophylaxis in young children, adolescents, and adults. Early initiation with prima-ry prophylaxis is ideal, but secondary prophylaxis in adolescents and adults has also demonstrated significant success. Because the standard of care includes prophylaxis with factor-concentrate replacement in order to prevent joint damage in patients with hemophilia, prophylaxis is now more common and needs to be addressed in all clinical settings, including managed care. However, further research is needed to help clinicians develop individualized factor-replacement protoc...

Summary.  Inherited deficiencies of plasma proteins involved in blood coagulation generally lead to lifelong bleeding disorders, whose severity is inversely proportional to the degree of factor deficiency. Haemophilia A and B, inherited as X-linked recessive traits, are the most common hereditary hemorrhagic disorders caused by a deficiency or dysfunction of blood coagulation factor VIII (FVIII) and factor IX (FIX). Together with von Willebrand's disease, a defect of primary haemostasis, these X-linked disorders include 95% to 97% of all the inherited deficiencies of coagulation factors. The remaining defects, generally transmitted as autosomal recessive traits, are rare with prevalence of the presumably homozygous forms in the general population of 1:500.000 for FVII deficiency and 1 in 2 million for prothrombin (FII) and factor XIII (FXIII) deficiency. Molecular characterization, carrier detection and prenatal diagnosis remain the key steps for the prevention of the birth of children affected by coagulation disorders in developing countries, where patients with these deficiencies rarely live beyond childhood and where management is still largely inadequate. These characterizations are possible by direct or indirect genetic analysis of genes involved in these diseases, and the choice of the strategy depends on the effective available budget and facilities to achieve a large benefit. In countries with more advanced molecular facilities and higher budget resources, the most appropriate choice in general is a direct strategy for mutation detection. However, in countries with limited facilities and low budget resources, carrier detection and prenatal diagnosis are usually performed by linkage analysis with genetic markers. This article reviews the genetic diagnosis of haemophilia, genetics and inhibitor development, genetics of von Willebrand's disease and of rare bleeding disorders.

Summary.  This paper outlines the results obtained in a cross-sectional study of a group of young patients with severe haemophilia A and B. The primary aim of the study was to ascertain the level of orthopaedic complications in the group, the effects that these complications have on quality of life, and the medical resources used on these patients. The secondary aim was to relate their current orthopaedic state to the type of treatment received before the study. The study was carried out in 11 hospitals in Spain, where 70 severe haemophilia patients (factor VIII [FVIII] < 2%), with an average age of 21.6 and a median age of 22, and no inhibitors, were monitored. The percentage of patients suffering from articular complaints was 84.3% and 85.7% according to the Gilbert and Petterson scales, respectively. Furthermore, pain was reported in 16.1% of joints, most frequently in ankles. Using the SF-36 Health Survey, patients were observed to have a poorer quality of life relative to healthy controls. Despite high levels of both the coagulant factor given to patients and the financial resources dedicated to their treatment, the type of treatment (on demand and/or as secondary prophylaxis) provided to the young adults was found to be incapable of preventing haemophilic arthropathy and subsequent negative quality of life consequences.

Specific research studies for the investigation of physical performance in haemophilic patients are rare. However, these instruments become increasingly more important to evaluate therapeutic treatments. Within the frame of the Haemophilia &amp;amp; Exercise Project (HEP), a new questionnaire, namely HEP-Test-Q, has been developed for the assessment of subjective physical performance in haemophilic adults. In this article, the development and validation of the HEP-Test-Q is described. The development consisted of different phases including item collection, pilot testing and field testing. The preliminary version was pilot-tested in 24 German HEP-participants. Following evaluation and preliminary psychometric analysis, the HEP-Test-Q was revised. The final version consists of 25 items pertaining to the domains &amp;#39;mobility&amp;#39;, &amp;#39;strength &amp;amp; coordination&amp;#39;, &amp;#39;endurance&amp;#39; and &amp;#39;body perception&amp;#39;, which was administered to 43 German haemophilic patients (43.8 +/- 11.2 years). Psychometric analysis included reliability and validity testing. Convergent validity was tested correlating the HEP-Test-Q with SF-36, Haem-A-QoL, HAL and the Orthopaedic Joint Score. Discriminant validity tested different clinical subgroups. Patients accepted the questionnaire and found it easy to fill in. Psychometric testing revealed good values for reliability in terms of internal consistency (Cronbach&amp;#39;s alpha = 0.96) and test-retest reliability (r = 0.90) as well as for convergent validity correlating highly with Haem-A-QoL, HAL and SF-36. Discriminant validity testing showed significant differences for age, hepatitis A and hepatitis B and the number of target joints. HEP-Test-Q is a short and well-accepted questionnaire, assessing subjective physical performance of haemophiliacs, which might be combined with objective assessments to reveal aspects, which cannot be measured objectively, such as body perception.

The Committee of Latin America on the Therapeutics of Inhibitor Groups (CLOTTING) is composed of a number of hemophilia specialists from Latin America. The group aims to encourage the adoption of a good standard of care for Latin American patients with hemophilia. The occurrence of inhibitors in patients with hemophilia poses clinical challenges, and it is estimated that between 1000 and 3000 patients in Latin America are affected by hemophilia with inhibitors. There is an urgent need to establish a regional consensus and clinical guidelines for the diagnosis and treatment of these patients. We present an extensive review based on best current clinical practice and published literature, as seen from a Latin American perspective, taking into account the variable nature of hemophilia care available in the various countries in this Region.

Hemophilia B, or factor IX deficiency, is an X-linked recessive disorder occurring in about 1 in 25,000 males. Affected individuals are at risk for spontaneous bleeding into many organs; treatment mainly consists of the transfusion of clotting factor concentrates prepared from human blood or recombinant sources after bleeding has started. Small- and large-animal models have been developed and/or characterized that closely mimic the human disease state. As a preclinical model for gene therapy, recombinant adeno-associated viral vectors containing the human or canine factor IX cDNAs were infused into the livers of murine and canine models of hemophilia B, respectively. There was no associated toxicity with infusion in either animal model. Constitutive expression of factor IX was observed, which resulted in the correction of the bleeding disorder over a period of over 17 months in mice. Mice with a steady-state concentration of 25% of the normal human level of factor IX had normal coag...