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Moghadam AA, Manafzadeh AR, Dajliry K, Ramezan F, Nikoonia MR, Abdolkarimi B, Hamidpour M, Tabibian S. Genotype-phenotype analyses of Iranian patients with hemophilia B (Leyden -) and hemophilia B (Leyden +): A single-center study. Transfus Apher Sci 2024; 63:103962. [PMID: 38964254 DOI: 10.1016/j.transci.2024.103962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 06/15/2024] [Accepted: 06/19/2024] [Indexed: 07/06/2024]
Abstract
BACKGROUND There is a high prevalence of inherited bleeding disorders in Iran, such as hemophilia A (HA) and hemophilia B (HB). This study aimed to analyze the molecular and clinical profiles of patients with HB. METHODS A single-center study was conducted among patients with severe HB between March 20, 2000, and June 31, 2023. The polymerase chain reaction (PCR) amplification was used for all of the major regions, such as the promoter, the exons, the adjacent intronic regions, and the untranslated regions of the F9 gene. Finally, Sanger sequencing was performed on the PCR products. RESULTS A total of 111 HB patients (17 with HB [Leyden +] and 94 with HB [Leyden -]) were enrolled in this study. Among 94 patients with HB (Leyden -), 59 (62.8 %) had missense, 21 (22.3 %) had nonsense, and 8 (8.5 %) had frameshift mutations. Moreover, the most frequent pathogenic variant in HB (Leyden +) was c.-17 A>G in this study. CONCLUSION The results of this study confirm that HB is caused by a wide range of molecular defects in Iran. Thus, by knowing the genotypes and phenotypes, we would be able to stratify the patients which is important in terms of their management and outcome.
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Affiliation(s)
- Arash Ahmadfard Moghadam
- Department of Hematology and Blood Banking, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Amir Reza Manafzadeh
- Department of Internal Medicine, Albert Szent-Györgyi Health Centre, University of Szeged, Szeged 6726, Hungary
| | - Khadijeh Dajliry
- Blood Disease Research Center (BDRC), Iranian Comprehensive Hemophilia Care Center, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Farahnaz Ramezan
- Blood Disease Research Center (BDRC), Iranian Comprehensive Hemophilia Care Center, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Mohammad Reza Nikoonia
- Blood Disease Research Center (BDRC), Iranian Comprehensive Hemophilia Care Center, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Babak Abdolkarimi
- Pediatric Hematology-Oncology, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Mohsen Hamidpour
- Hematopoietic Stem Cell Research Centre-Department of Hematology and Blood Banking, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Shadi Tabibian
- Blood Disease Research Center (BDRC), Iranian Comprehensive Hemophilia Care Center, Iran University of Medical Sciences (IUMS), Tehran, Iran.
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Wang W, Xu L, Wu J, Liu W, Jin J, Huang J, Xu Z, Huang Y, Li B, Liu Y, Zhang Q, Zhou M, Peng J, Hu Q. Clinical analysis and quality of life survey of hemophilia B patients in the central and western regions of China. Front Pediatr 2024; 12:1366990. [PMID: 38783919 PMCID: PMC11111977 DOI: 10.3389/fped.2024.1366990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 04/25/2024] [Indexed: 05/25/2024] Open
Abstract
Objective To study the current status of hemophilia B (HB) patients in the central and western regions of China. Methods This cross-sectional, multicenter study was conducted in seven provinces in the central and western regions of China from April 2019 to June 2023. Samples were collected for the factor IX activity, inhibitor screen, and gene mutation. Furthermore, the status of six index joints and quality of life (QoL) were assessed. Results A total of 185 HB patients (mild 15, moderate 75, and severe 95) with a median age of 12.17 years were enrolled. 30.3% (56/185) of patients had a family history of HB. 34.6% (64/185) of HB patients had diagnostic delay and 38.5% (69/179) experienced treatment delay. The incidence of inhibitors was 6.1% (11/179). We identified 123 genetic variants in this study, with missense mutations being the most common. 84.0% (89/106) of HB mothers were genetically identified as carriers, with 27.7% (13/47) of carriers having clotting factor levels less than 0.40 IU/ml. 71.4% (132/185) of HB patients had a history of joint hemorrhage, with a rate of target joint in these patients was 64.4% (85/132). Lower extremity joints were most often affected in patients. The Hemophilia Joint Health Score (HJHS) score was significantly positively correlated with the Hemophilia Early Arthropathy Detection with Ultrasound in China (HEAD-US-C) (r = 0.542, P < 0.001). Patients who received prevention treatment, inhibitor negative, without treatment delay, and without high-intensity replacement therapy showed a higher total score of the short form-36 health survey (SF-36). Conclusions One-third of HB patients had delay in diagnosis and treatment, and the incidence of inhibitors was 6.1%. Target joints were present in nearly half of HB patients. Missense was the main mutation type. 84.0% of mothers of HB patients in this study were found to be carriers. HEAD-US-C and HJHS can complement each other in the evaluation of joint status and give a valid basis for early clinical management. Early detection and preventive treatment, as well as reducing high-intensity replacement therapy and inhibitor generation, can effectively improve the QoL of patients.
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Affiliation(s)
- Wen Wang
- Department of Pediatrics, Huazhong University of Science and Technology Tongji Medical College Tongji Hospital, Wuhan, China
| | - Li Xu
- Department of Hematology, The Second People's Hospital of Anhui Province, Hefei, China
| | - Jingsheng Wu
- Department of Hematology, The First Affiliated Hospital of University of Science and Technology of China, Hefei, China
| | - Weiyong Liu
- Department of Ultrasound, The First Affiliated Hospital of University of Science and Technology of China, Hefei, China
| | - Jiao Jin
- Department of Pediatrics, The Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Jing Huang
- Department of Pediatrics, The Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Zhongjin Xu
- Department of Hematology, Jiangxi Provincial Children's Hospital, Nanchang, China
| | - Yali Huang
- Department of Hematology, Jiangxi Provincial Children's Hospital, Nanchang, China
| | - Bai Li
- Department of Pediatrics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Yufeng Liu
- Department of Pediatrics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Qing Zhang
- Haemophilia Diagnosis and Treatment Center, Department of Hematology and Oncology, Chengdu Women's and Children's Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Min Zhou
- Haemophilia Diagnosis and Treatment Center, Department of Hematology and Oncology, Chengdu Women's and Children's Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Jie Peng
- Department of Hematology, Xiangya Hospital Central South University, Changsha, China
| | - Qun Hu
- Department of Pediatrics, Huazhong University of Science and Technology Tongji Medical College Tongji Hospital, Wuhan, China
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Bester C, Kloppers JF, van Rensburg WJJ. Genetic variant detection in a South African haemophilia B population. Haemophilia 2024; 30:765-773. [PMID: 38462783 DOI: 10.1111/hae.14978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 02/15/2024] [Accepted: 02/18/2024] [Indexed: 03/12/2024]
Abstract
BACKGROUND Haemophilia B is characterised by a deficiency of factor IX (FIX) protein due to genetic variants in the FIX gene (F9). Genetic testing may have a vital role in effectively managing haemophilia B. However, in many developing countries, comprehensive genetic variant detection is unavailable. This study aimed to address the lack of genetic data in our country by conducting genetic variant detection on people affected by haemophilia B in our region. METHODS Twenty-one participants were screened with a direct Sanger sequencing method to identify variants in the F9 gene. The identified variants were then compared to previously published variants and/or to a reference database. RESULTS AND DISCUSSION A total of ten F9 genetic changes were detected, with five of them being novel. These identified variants were distributed across different domains of the FIX protein. Only one participant had a history of inhibitor formation against FIX replacement therapy. Notably, this participant had two distinct genetic changes present adjacent to each other. Thus, we hypothesise that the presence of multiple variants within the same functional region of the gene may increase the risk for inhibitor development. CONCLUSION The discovery of novel pathogenic variations in the F9 gene highlights the importance of genetic analysis in specific geographical regions. The possible link between a complex variant and inhibitor formation illustrates the potential role that genetic screening has as a pre-treatment tool in predicting treatment reactions and outcomes.
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Affiliation(s)
- Chené Bester
- Faculty of Health Sciences, Human Molecular Biology Unit, School of Biomedical Sciences, University of the Free State, Bloemfontein, South Africa
| | - Jean F Kloppers
- Faculty of Health Sciences, Department of Haematology and Cell Biology, School of Pathology, University of the Free State, Bloemfontein, South Africa
- National Health Laboratory Service, Universitas Academic Business Unit, Bloemfontein, South Africa
| | - Walter J Janse van Rensburg
- Faculty of Health Sciences, Human Molecular Biology Unit, School of Biomedical Sciences, University of the Free State, Bloemfontein, South Africa
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Wang W, Jiang LJ, Cui DY, Zhang A, Wang X, Liu AG, Hu Q. Clinical Analysis and Mental Health Survey of Hemophilia Carriers: a Cross-sectional Study. Curr Med Sci 2024; 44:435-440. [PMID: 38561593 DOI: 10.1007/s11596-024-2855-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 02/20/2024] [Indexed: 04/04/2024]
Abstract
OBJECTIVE Hemophilia carriers (HCs), who are heterozygous for mutations in the clotting factor VIII/clotting factor IX gene (F8 or F9), may have a wide range of clotting factor levels, from very low, similar to afflicted males, to the upper limit of normal, and may experience mental health issues. The purpose of this study was to provide genetic information on mothers of hemophilia patients and to understand the clotting factor activity and phenotype of HCs. Additionally, we aimed to investigate the mental health status of HCs in China. METHODS A total of 127 hemophilia mothers, including 93 hemophilia A (HA) mothers and 34 hemophilia B (HB) mothers, were enrolled in this study. Long distance PCR, multiplex PCR, and Sanger sequencing were used to analyze mutations in F8 or F9. Coagulation factor activity was detected by a one-stage clotting assay. The Symptom Checklist 90 (SCL-90, China/Mandarin version) was given to HCs at the same time to assess their mental health. RESULTS A total of 90.6% of hemophilia mothers were diagnosed genetically as carriers, with inversion in intron 22 and missense mutations being the most common mutation types in HA and HB carriers, respectively. The median clotting factor level in carriers was 0.74 IU/mL (ranging from 0.09 to 1.74 IU/mL) compared with 1.49 IU/mL (ranging from 0.93 to 1.89 IU/mL) in noncarriers, of which 14.3% of HCs had clotting factor levels of 0.40 IU/mL or below. A total of 53.8% (7/13) of HA carriers with low clotting factor levels (less than 0.50 IU/mL) had a history of bleeding, while none of the HB carriers displayed a bleeding phenotype. The total mean score and the global severity index of the SCL-90 for surveyed HCs were 171.00 (±60.37) and 1.78 (±0.59), respectively. A total of 67.7% of the respondents had psychological symptoms, with obsessive-compulsive disorder being the most prevalent and severe. The pooled estimates of all nine factors were significantly higher than those in the general population (P<0.05). CONCLUSIONS The detection rate of gene mutations in hemophilia mothers was 90.6%, with a median clotting factor level of 0.74 IU/mL, and 14.3% of HCs had a clotting factor level of 0.40 IU/mL or below. A history of bleeding was present in 41.2% of HCs with low clotting factor levels (less than 0.50 IU/mL). Additionally, given the fragile mental health status of HCs in China, it is critical to develop efficient strategies to improve psychological well-being.
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Affiliation(s)
- Wen Wang
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Li-Juan Jiang
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Dong-Yan Cui
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Ai Zhang
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Xiong Wang
- Department of Laboratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Ai-Guo Liu
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Qun Hu
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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Xu Z, Spencer HJ, Harris VA, Perkins SJ. An updated interactive database for 1692 genetic variants in coagulation factor IX provides detailed insights into hemophilia B. J Thromb Haemost 2023; 21:1164-1176. [PMID: 36787808 DOI: 10.1016/j.jtha.2023.02.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 01/24/2023] [Accepted: 02/06/2023] [Indexed: 02/14/2023]
Abstract
BACKGROUND Genetic variants in coagulation factor IX (FIX) are associated with hemophilia B, a rare bleeding disease. F9 variants are widespread across the gene and were summarized in our FIX variant database introduced in 2013. OBJECTIVES We aimed to rationalize the molecular basis for 598 new F9 variants and 1645 new clinical cases, totaling 1692 F9 variants and 5358 related patient cases. METHODS New F9 variants were identified from publications and online resources, and compiled into a MySQL database for comparison with the human FIXa protein structure. RESULTS The new total of 1692 F9 variants correspond to 406 (88%) of the 461 FIX residues and now include 70 additional residues. They comprise 945 unique point variants, 281 deletions, 352 polymorphisms, 63 insertions, and 51 others. Most FIX variants were point variants, although their proportion (56%) has reduced compared to 2013 (73%); at the same time, the proportion of polymorphisms has increased from 5% to 21%. The 764 unique mild severity variants in the mature protein with known phenotypes include 74 (9.7%) quantitative type I variants and 116 (15.2%) predominantly qualitative type II variants. The remaining 574 variants types are unspecified. Inhibitors are associated with 152 hemophilia B cases out of 5358 patients (2.8%), an increase of 93 from the previous database. CONCLUSION The even distribution of the F9 variants revealed few mutational hotspots, and most variants were associated with small perturbations in the FIX protein structure. The updated database will assist clinicians and researchers in assessing treatments for patients with hemophilia B.
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Affiliation(s)
- Ziqian Xu
- Research Department of Structural and Molecular Biology, University College London, London, UK
| | - Holly J Spencer
- Research Department of Structural and Molecular Biology, University College London, London, UK
| | - Victoria A Harris
- Research Department of Structural and Molecular Biology, University College London, London, UK
| | - Stephen J Perkins
- Research Department of Structural and Molecular Biology, University College London, London, UK.
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Agrawal N, Kumar R, Masih S, Srivastava P, Singh P, Jaiswal SK, Moirangthem A, Saxena D, Phadke SR, Mandal K. Molecular analysis of severe hemophilia B in Indian families: Identification of mutational hotspot and novel variants. Int J Lab Hematol 2021; 44:186-192. [PMID: 34590426 DOI: 10.1111/ijlh.13715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 09/04/2021] [Accepted: 09/07/2021] [Indexed: 11/27/2022]
Abstract
INTRODUCTION Hemophilia B is associated with molecular heterogeneity, with more than 1200 unique variants in the F9 gene. We hereby describe the mutational spectrum of severe hemophilia B patients presenting in a tertiary-care center in India. METHOD DNA was extracted from peripheral blood samples of 35 diagnosed severe hemophilia B patients belonging to 32 families, and were subjected to Sanger sequencing. Determination of the effect of novel variants on the protein structure and correlation between genotype and phenotype was attempted using in-silico tools. RESULTS Twenty-seven different mutations were detected in 30 probands, including 20 known and 7 novel variants. Also, we found one suspected case of whole gene deletion. The serine peptidase domain harbored most of the variants (48.1%). Inhibitory antibodies were found in two patients. CONCLUSIONS This study provides a comprehensive mutational spectrum and mutation screening strategy by Sanger sequencing of F9 gene in severe hemophilia B patients, in a resource-constraint setting.
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Affiliation(s)
- Neha Agrawal
- Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
| | - Ravi Kumar
- Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
| | - Suzena Masih
- Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
| | - Priyanka Srivastava
- Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
| | - Parshw Singh
- Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
| | - Sushil Kumar Jaiswal
- Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
| | - Amita Moirangthem
- Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
| | - Deepti Saxena
- Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
| | - Shubha R Phadke
- Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
| | - Kausik Mandal
- Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
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El-Kamah GY, Mosaad RM, Taher MB, Amr KS. Defining the molecular pathology and consequent phenotypes in Egyptian HB patients. J Genet Eng Biotechnol 2021; 19:75. [PMID: 33999344 PMCID: PMC8128942 DOI: 10.1186/s43141-021-00165-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 04/14/2021] [Indexed: 11/18/2022]
Abstract
BACKGROUND Hemophilia B (HB) (also known as Christmas disease) is a rare X-linked recessive disorder characterized by spontaneous or prolonged hemorrhages caused by mutations in Factor 9 (F9) gene leading to deficient or defective coagulation F9. Our study aimed at identifying the causative mutations within a sample of HB Egyptian patients. The present study comprised clinical data of eleven HB patients descending from six unrelated families and a seventh family including a carrier mother with a history of deceased HB sibling. Sequencing of F9 gene was performed. RESULTS The study revealed four mutations; two missense NM_000133.3:c.676C>G, (P.Arg226Gly) and NM_000133.3:c.1305T>G, (p.Cys435Trp), and two nonsense mutations NM_000133.3:c.880C>T, (p.Arg294*) and NM_000133.3:c.1150C>T, (p.Arg384*), identified mutations spanned exons 6 and 8 of which a total of three mutations are located in hotspot exon 8 of F9 gene. CONCLUSIONS Reviewing the literature, this is the first molecular analysis of F9 gene in HB Egyptian patients. Consistent genotype/phenotypic severity correlation could be concluded, helping proper genetic counseling and prenatal decision taking.
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Affiliation(s)
- Ghada Y El-Kamah
- Clinical Genetics Department, Human Genetics and Genome Research division (HGGR), National Research Centre (NRC), Cairo, Egypt
| | - Rehab M Mosaad
- Molecular Genetics and Enzymology Department, HGGR, NRC, El Buhouth St., Dokki, Cairo, Egypt.
| | - Mohamed B Taher
- Clinical Genetics Department, Human Genetics and Genome Research division (HGGR), National Research Centre (NRC), Cairo, Egypt
| | - Khalda S Amr
- Medical Molecular Genetics, HGGR, NRC, Cairo, Egypt
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Schieve LA, Byams VR, Dupervil B, Oakley MA, Miller CH, Soucie JM, Abe K, Bean CJ, Hooper WC. Evaluation of CDC's Hemophilia Surveillance Program - Universal Data Collection (1998-2011) and Community Counts (2011-2019), United States. MMWR. SURVEILLANCE SUMMARIES : MORBIDITY AND MORTALITY WEEKLY REPORT. SURVEILLANCE SUMMARIES 2020; 69:1-18. [PMID: 32881847 PMCID: PMC8797870 DOI: 10.15585/mmwr.ss6905a1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Problem/Condition Hemophilia is an X-linked genetic disorder that primarily affects males and results in deficiencies in blood-clotting proteins. Hemophilia A is a deficiency in factor VIII, and hemophilia B is a deficiency in factor IX. Approximately one in 5,000 males are born with hemophilia, and hemophilia A is about four times as common as hemophilia B. Both disorders are characterized by spontaneous internal bleeding and excessive bleeding after injuries or surgery. Hemophilia can lead to repeated bleeding into the joints and associated chronic joint disease, neurologic damage, damage to other organ systems, and death. Although no precise national U.S. prevalence estimates for hemophilia exist because of the difficulty identifying cases among persons who receive care from various types of health care providers, two previous state-based studies estimated hemophilia prevalence at 13.4 and 19.4 per 100,000 males. In addition, these studies showed that 67% and 82% of persons with hemophilia received care in a federally funded hemophilia treatment center (HTC), and 86% and 94% of those with the most severe cases of hemophilia (i.e., those with the lowest levels of clotting factor activity in the circulating blood) received care in a federally funded HTC. As of January 2020, the United States had 144 HTCs. Period Covered 1998–2019. Description of the System Surveillance for hemophilia, which is a complex, chronic condition, is challenging because of its low prevalence, the difficulty in ascertaining cases uniformly, and the challenges in routinely characterizing and tracking associated health complications. Over time, two systems involving many stakeholders have been used to conduct ongoing hemophilia surveillance. During 1998–2011, CDC and the HTCs collaborated to establish the Universal Data Collection (UDC) surveillance system. The purposes of the UDC surveillance system were to monitor human immunodeficiency virus (HIV) and bloodborne viral hepatitis in persons with hemophilia, thereby tracking blood safety, and to track the prevalence of and trends in complications associated with hemophilia. HTC staff collected clinical data and blood specimens from UDC participants and submitted them to CDC. CDC tested specimens for viral hepatitis and HIV. In 2011, the UDC surveillance system was replaced by a new hemophilia surveillance system called Community Counts. CDC and the HTCs established Community Counts to expand laboratory testing and the collection of clinical data to better identify and track emerging health issues in persons with hemophilia. Results This report is the first comprehensive summary of CDC’s hemophilia surveillance program, which comprises both UDC and Community Counts. Data generated from these surveillance systems have been used in the development of public health and clinical guidelines and practices to improve the safety of U.S. blood products and either prevent hemophilia-related complications or identify complications early. Several factors have played a role in the effectiveness of the UDC and Community Counts systems, including 1) a stable data collection design that was developed and is continually reviewed in close partnership with HTC regional leaders and providers to ensure surveillance activities are focused on maximizing the scientific and clinical impact; 2) flexibility to respond to emerging health priorities through periodic updates to data collection elements and special studies; 3) high data quality for many clinical indicators and state-of-the-art laboratory testing methods for hemophilia treatment product inhibitors (developed and refined in part based on CDC research); 4) timely data and specimen collection and submission, laboratory specimen testing, analysis, and reporting; and 5) the largest and most representative sample of persons with hemophilia in the United States and one of the largest and most comprehensive data collection systems on hemophilia worldwide. Interpretation CDC has successfully developed, implemented, and maintained a surveillance system for hemophilia. The program can serve as an example of how to conduct surveillance for a complex chronic disease by involving stakeholders, improving and building new infrastructure, expanding data collection (e.g., new diagnostic assays), providing testing guidance, establishing a registry with specimen collection, and integrating laboratory findings in clinical practice for the individual patient. Public Health Action Hemophilia is associated with substantial lifelong morbidity, excess premature deaths, and extensive health care needs throughout life. Through monitoring data from Community Counts, CDC will continue to characterize the benefits and adverse events associated with existing or new hemophilia treatment products, thereby contributing to maximizing the health and longevity of persons with hemophilia.
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Affiliation(s)
- Laura A Schieve
- Division of Blood Disorders, National Center on Birth Defects and Developmental Disabilities, CDC
| | - Vanessa R Byams
- Division of Blood Disorders, National Center on Birth Defects and Developmental Disabilities, CDC
| | - Brandi Dupervil
- Division of Blood Disorders, National Center on Birth Defects and Developmental Disabilities, CDC
| | - Meredith A Oakley
- Division of Blood Disorders, National Center on Birth Defects and Developmental Disabilities, CDC
| | - Connie H Miller
- Division of Blood Disorders, National Center on Birth Defects and Developmental Disabilities, CDC
| | - J Michael Soucie
- Division of Blood Disorders, National Center on Birth Defects and Developmental Disabilities, CDC
| | - Karon Abe
- Division of Blood Disorders, National Center on Birth Defects and Developmental Disabilities, CDC
| | - Christopher J Bean
- Division of Blood Disorders, National Center on Birth Defects and Developmental Disabilities, CDC
| | - W Craig Hooper
- Division of Blood Disorders, National Center on Birth Defects and Developmental Disabilities, CDC
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9
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Huang L, Li L, Lin S, Chen J, Li K, Fan D, Jin W, Li Y, Yang X, Xiong Y, Li F, Yang X, Li M, Li Q. Molecular analysis of 76 Chinese hemophilia B pedigrees and the identification of 10 novel mutations. Mol Genet Genomic Med 2020; 8:e1482. [PMID: 32875744 PMCID: PMC7667291 DOI: 10.1002/mgg3.1482] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 08/05/2020] [Accepted: 08/06/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Hemophilia B (HB) is an X-linked recessive inherited bleeding disorder caused by mutations in the F9 gene that lead to plasma factor IX deficiency. To identify the causative mutations in HB, a molecular analysis of HB pedigrees in China was performed. METHODS Using next-generation sequencing (NGS) and an in-house bioinformatics pipeline, 76 unrelated HB pedigrees were analyzed. The mutations identified were validated by comparison with the results of Sanger sequencing or Multiplex Ligation-dependent Probe Amplification assays. The pathogenicity of the causative mutations was classified following the American College of Medical Genetics and Genomics guidelines. RESULTS The mutation detection rate was 94.74% (72/76) using NGS. Of the 76 HB pedigrees analyzed, 59 causative variants were found in 72 pedigrees, with 38 (64.41%) missense mutations, 9 (15.25%) nonsense mutations, 2 (3.39%) splicing mutations, 5 (8.47%) small deletions, 4 (6.78%) large deletions, and 1 intronic mutation (1.69%). Of the 59 different F9 mutations, 10 were novel: c.190T>G, c.199G>T, c.290G>C, c.322T>A, c.350_351insACAATAATTCCTA, c.391+5delG, c.416G>T, c.618_627delAGCTGAAACC, c.863delA, and c.1024_1027delACGA. Of these 10 novel mutations, a mosaic mutation, c.199G>T(p.Glu67Ter), was identified in a sporadic HB pedigree. Using in-silico analysis, these novel variants were predicted to be disease-causing. However, no potentially causative mutations were found in the F9 coding sequences of the four remaining HB pedigrees. In addition, two HB pedigrees carrying additional F8/F9 mutations were discovered. CONCLUSION The identification of these mutations enriches the spectrum of F9 mutations and provides further insights into the pathogenesis of HB in the Chinese population.
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Affiliation(s)
- Limin Huang
- Institute of Antibody Engineering, School of Laboratory Medicine and Biotechnology, Southern Medical University, Guangzhou, China
| | - Liyan Li
- Technology Center of Prenatal Diagnosis and Genetic Diseases Diagnosis, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Sheng Lin
- Laboratory of Molecular Medicine, Shenzhen Health Development Research Center, Shenzhen, China
| | - Juanjuan Chen
- Institute of Antibody Engineering, School of Laboratory Medicine and Biotechnology, Southern Medical University, Guangzhou, China
| | - Kun Li
- Institute of Antibody Engineering, School of Laboratory Medicine and Biotechnology, Southern Medical University, Guangzhou, China
| | - Dongmei Fan
- Institute of Antibody Engineering, School of Laboratory Medicine and Biotechnology, Southern Medical University, Guangzhou, China
| | - Wangjie Jin
- Technology Center of Prenatal Diagnosis and Genetic Diseases Diagnosis, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Yihong Li
- Technology Center of Prenatal Diagnosis and Genetic Diseases Diagnosis, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Xu Yang
- Clinical Innovation & Research Center (CIRC), Shenzhen Hospital of Southern Medical University, Shenzhen, China
| | - Yufeng Xiong
- Department of Clinical Laboratory, Guangdong Women and Children Hospital, Guangzhou, China
| | - Fenxia Li
- Technology Center of Prenatal Diagnosis and Genetic Diseases Diagnosis, Department of Gynecology and Obstetrics, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Xuexi Yang
- Institute of Antibody Engineering, School of Laboratory Medicine and Biotechnology, Southern Medical University, Guangzhou, China
| | - Ming Li
- Institute of Antibody Engineering, School of Laboratory Medicine and Biotechnology, Southern Medical University, Guangzhou, China
| | - Qiang Li
- The Department of Laboratory Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, China
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10
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Parrado Jara YA, Yunis Hazbun LK, Linares A, Yunis Londoño JJ. Molecular characterization of hemophilia B patients in Colombia. Mol Genet Genomic Med 2020; 8:e1210. [PMID: 32155688 PMCID: PMC7216803 DOI: 10.1002/mgg3.1210] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 02/02/2020] [Accepted: 02/24/2020] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Hemophilia B (HB) is a coagulation disorder with an X-linked recessive inheritance pattern, caused by plasma FIX deficiency. In Colombia, HB is considered a rare and high-cost disease, with 362 males reported in 2017. METHODS Here, we characterized 20 HB apparently unrelated families by PCR amplification and Sanger sequencing. RESULTS Fourteen unique variants were identified: seven missense, three nonsense, one variant in the 3' UTR region, two large deletions >50 bp, and one intronic substitution that affects splicing c.520+13A>G that was present in 7/20 patients (35%). All these variants have been previously reported in the literature, except for exons 3 and 4, deletions, present in one patient. The genotype-phenotype association correlates with the reported in the literature, with the exception of one patient. CONCLUSION This molecular analysis allowed us to establish the causal variant of HB in 100% of patients, to provide the appropriate genetic counseling to each of the families, and to propose a more cost-effective carrier analysis. Here, we reported the first variants in Colombian population with Hemophilia B, finding a new variant and one intron recurrent variant present in 35% of patients.
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Affiliation(s)
- Yolima A Parrado Jara
- Grupo de Patología Molecular, Universidad Nacional de Colombia, Bogotá D.C, Colombia.,Instituto de Genética Servicios Médicos Yunis Turbay y Cia. S.A.S., Bogotá D.C, Colombia
| | - Luz K Yunis Hazbun
- Grupo de Patología Molecular, Universidad Nacional de Colombia, Bogotá D.C, Colombia.,Instituto de Genética Servicios Médicos Yunis Turbay y Cia. S.A.S., Bogotá D.C, Colombia
| | - Adriana Linares
- Grupo de Oncohematología Pediátrica, Departamento de Pediatría, Facultad de Medicina, Universidad Nacional de Colombia, Bogotá D.C, Colombia.,Programa de Hemofilia, Clínica Infantil Colsubsidio, Bogotá D.C, Colombia
| | - Juan J Yunis Londoño
- Grupo de Patología Molecular, Universidad Nacional de Colombia, Bogotá D.C, Colombia.,Instituto de Genética Servicios Médicos Yunis Turbay y Cia. S.A.S., Bogotá D.C, Colombia.,Departamento de Patología, Facultad de Medicina, Universidad Nacional de Colombia, Bogotá D.C, Colombia
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11
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Davari M, Gharibnaseri Z, Ravanbod R, Sadeghi A. Health status and quality of life in patients with severe hemophilia A: A cross-sectional survey. Hematol Rep 2019; 11:7894. [PMID: 31285808 PMCID: PMC6589534 DOI: 10.4081/hr.2019.7894] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Accepted: 02/15/2019] [Indexed: 12/05/2022] Open
Abstract
Among different groups of hemophiliacs, those suffering from Severe Hemophilia A (SHA) are most vulnerable to the complications of the disease. This study investigated the Health-Related Quality of Life (HR-QoL) among adult patients with SHA. A cross-sectional study was designed to gather demographic and clinical information from adult patients with SHA. Patients with inhibitors were excluded. The remaining were asked to complete the HR-QoL questionnaire after being examined for joint health using the Hemophilia Joint Health Score (HJHS). The HR-QoL and joint conditions were measured in 38 patients. The mean EQ-5D value scores were 0.46 (SD=0.23) while the mean Visual Analogous Scale score was 50 (SD=18.7). The clinical examination of patients indicated that the HJHS were as follows: eight patients had a score of 55-75, 12 patients had a score of 40-55, 7 of them (25-40) and 11 patients had a score of 10-25. The results obtained from this study showed that HRQoL in hemophilia patients was considerably low. Pain, anxiety/depression, and motion limitations were the main causes of the disutility for these patients respectively.
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Affiliation(s)
- Majid Davari
- Department of Pharmacoeconomics and Pharmaceutical Administration, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran
- Health Equity Research Center, Tehran University of Medical Science, Tehran
| | - Zahra Gharibnaseri
- Department of Health Economics, National Institute for Health Research, Tehran University of Medical Science, Tehran
| | - Roya Ravanbod
- Department of Physiotherapy, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Abolfazl Sadeghi
- Department of Pharmacoeconomics and Pharmaceutical Administration, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran
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12
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Lu Y, Wu X, Dai J, Ding Q, Wu W, Wang X. The characteristics and spectrum of F9 mutations in Chinese sporadic haemophilia B pedigrees. Haemophilia 2019; 25:316-323. [PMID: 30648777 DOI: 10.1111/hae.13681] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 07/06/2018] [Accepted: 12/20/2018] [Indexed: 01/01/2023]
Abstract
INTRODUCTION Sporadic haemophilia B (HB) without obvious familial history poses challenges for genetic diagnosis and counselling. AIM To identify the F9 variants in sporadic HB patients and probe the origin of these de novo mutations. METHOD A total of 294 unrelated HB pedigrees sought genetic diagnosis were analysed in this single-centre study. The F9 gene was analysed by direct sequencing, and AccuCopy technique was adopted to screen for gene copy number variations. Six short tandem repeats approximal or within F9 gene were applied for linkage analysis. Mosaicism of sequence variant was determined by ddNTP Primer Extension method. RESULTS Sporadic HB patients constituted 36% (61/294) of cases enrolled in current study. The sporadic and familial HB patients shared similar spectrum of F9 variants, with single nucleotide substitution as predominant form of disease-causing mutation and no mutation prone hotspot sites, including CpG dinucleotide sequences, had been identified. Majority of the mothers of sporadic HB patients were F9 mutation carriers (70%, 43/61), and most of them (95%, 41/43) had the inherited bleeding trait traced back to maternal grandfathers. Although most de novo mutations occur in germ cells, 2 maternal grandfathers, who had somatic mosaic mutations of F9, were also revealed to be the source of genetic variations identified in patients. In our cohort, FIX inhibitor incidence was 1%, developed only in patients carrying null mutations. CONCLUSION The diversity of F9 genetic variants and possible mosaicism of de novo mutation demand extensive study and more cautious in genetic counselling of sporadic HB.
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Affiliation(s)
- Yeling Lu
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xi Wu
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jing Dai
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qiulan Ding
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wenman Wu
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xuefeng Wang
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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13
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Abstract
Hemostasis is the normal process of blood coagulation in vivo to stop pathologic bleeding. Virchow triad includes venous stasis, hypercoagulability, and vascular injury. Natural anticoagulants include protein C, protein S, and antithrombin. Factor V Leiden is the most common inherited thrombophilia, followed by prothrombin gene mutation. All inherited thrombophilias are passed down in an autosomal dominant fashion. Patients harboring the antiphospholipid antibodies have an increased risk for thrombosis. von Willebrand disease is the most common inherited bleeding disorder; the pattern of inheritance is autosomal. Hemophilia A and B are the only hereditary bleeding disorders inherited in a sex-linked recessive pattern.
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14
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Ljung RCR. How I manage patients with inherited haemophilia A and B and factor inhibitors. Br J Haematol 2017; 180:501-510. [DOI: 10.1111/bjh.15053] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Rolf C. R. Ljung
- Department of Clinical Sciences - Paediatrics; Lund University; Lund Sweden
- Centre for Thrombosis and Haemostasis; Skåne University Hospital Malmö; Malmo Sweden
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15
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Belvini D, Salviato R, Radossi P, Tagariello G. Multiplex ligation-dependent probe amplification as first mutation screening for large deletions and duplications in haemophilia. Haemophilia 2017; 23:e124-e132. [DOI: 10.1111/hae.13143] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2016] [Indexed: 12/24/2022]
Affiliation(s)
- D. Belvini
- Transfusion Service; Haemophilia Centre and Haematology; Castelfranco Veneto Hospital; Castelfranco Veneto Italy
| | - R. Salviato
- Transfusion Service; Haemophilia Centre and Haematology; Castelfranco Veneto Hospital; Castelfranco Veneto Italy
| | - P. Radossi
- Transfusion Service; Haemophilia Centre and Haematology; Castelfranco Veneto Hospital; Castelfranco Veneto Italy
| | - G. Tagariello
- Transfusion Service; Haemophilia Centre and Haematology; Castelfranco Veneto Hospital; Castelfranco Veneto Italy
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16
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Wang QY, Hu B, Liu H, Tang L, Zeng W, Wu YY, Cheng ZP, Hu Y. A genetic analysis of 23 Chinese patients with hemophilia B. Sci Rep 2016; 6:25024. [PMID: 27109384 PMCID: PMC4842959 DOI: 10.1038/srep25024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 04/08/2016] [Indexed: 11/17/2022] Open
Abstract
Hemophilia B (HB) is an X-linked recessive bleeding disorder caused by mutations in the coagulation factor IX (FIX) gene. Genotyping patients with HB is essential for genetic counseling and provides useful information for patient management. In this study, the F9 gene from 23 patients with HB was analyzed by direct sequencing. Nineteen point mutations were identified, including a novel missense variant (c.520G > C, p.Val174Leu) in a patient with severe HB and a previously unreported homozygous missense mutation (c.571C > T, p.Arg191Cys) in a female patient with mild HB. Two large F9 gene deletions with defined breakpoints (g.10413_11363del, g.12163_23369del) were identified in two patients with severe HB using a primer walking strategy followed by sequencing. The flanking regions of the two breakpoints revealed recombination-associated elements (repetitive elements, non-B conformation forming motifs) with a 5-bp microhomology in the breakpoint junction of g.12163_23369del. These findings imply that non-homologous end joining and microhomology-mediated break-induced replication are the putative mechanisms for the deletions of the F9 gene. Because the g.12163_23369del deletion caused exons to be absent without a frameshift mutation occurring, a smaller FIX protein was observed in western blot analyses.
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Affiliation(s)
- Qing-Yun Wang
- Institute of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430022, China.,Collaborative Innovation Center of Hematology, Union Hospital, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Bei Hu
- Institute of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430022, China.,Collaborative Innovation Center of Hematology, Union Hospital, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Hui Liu
- Institute of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430022, China
| | - Liang Tang
- Institute of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430022, China.,Collaborative Innovation Center of Hematology, Union Hospital, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Wei Zeng
- Institute of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430022, China.,Collaborative Innovation Center of Hematology, Union Hospital, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Ying-Ying Wu
- Institute of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430022, China
| | - Zhi-Peng Cheng
- Institute of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430022, China.,Collaborative Innovation Center of Hematology, Union Hospital, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Yu Hu
- Institute of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430022, China.,Collaborative Innovation Center of Hematology, Union Hospital, Huazhong University of Science and Technology, Wuhan, 430022, China
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17
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Surin VL, Demidova EY, Selivanova DS, Luchinina YA, Salomashkina VV, Pshenichnikova OS, Likhacheva EA. Mutational analysis of hemophilia B in Russia: Molecular-genetic study. RUSS J GENET+ 2016. [DOI: 10.1134/s1022795416040116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Mårtensson A, Letelier A, Halldén C, Ljung R. Mutation analysis of Swedish haemophilia B families – high frequency of unique mutations. Haemophilia 2015; 22:440-5. [DOI: 10.1111/hae.12854] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2015] [Indexed: 01/19/2023]
Affiliation(s)
- A. Mårtensson
- Department of Clinical Sciences Lund University Malmö Sweden
- Department of Paediatrics and Malmö Centre for Thrombosis and Haemostasis Skåne University Hospital Lund University Malmö Sweden
| | - A. Letelier
- Department of Clinical Sciences Lund University Malmö Sweden
- Department of Paediatrics and Malmö Centre for Thrombosis and Haemostasis Skåne University Hospital Lund University Malmö Sweden
| | - C. Halldén
- Biomedicine Kristianstad University Kristianstad Sweden
| | - R. Ljung
- Department of Clinical Sciences Lund University Malmö Sweden
- Department of Paediatrics and Malmö Centre for Thrombosis and Haemostasis Skåne University Hospital Lund University Malmö Sweden
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19
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Abstract
Hemophilia B is an X-chromosome-linked inherited bleeding disorder primarily affecting males, but those carrier females with reduced factor IX activity (FIX:C) levels may also experience some bleeding. Genetic analysis has been undertaken for hemophilia B since the mid-1980s, through linkage analysis to track inheritance of an affected allele, and to enable determination of the familial mutation. Mutation analysis using PCR and Sanger sequencing along with dosage analysis for detection of large deletions/duplications enables mutation detection in > 97% of patients with hemophilia B. The risk of the development of inhibitory antibodies, which are reported in ~ 2% of patients with hemophilia B, can be predicted, especially in patients with large deletions, and these individuals are also at risk of anaphylaxis, and nephrotic syndrome if they receive immune tolerance induction. Inhibitors also occur in patients with nonsense mutations, occasionally in patients with small insertions/deletions or splice mutations, and rarely in patients with missense mutations (p.Gln237Lys and p.Gln241His). Hemophilia B results from several different mechanisms, and those associated with hemophilia B Leyden, ribosome readthrough of nonsense mutations and apparently 'silent' changes that do not alter amino acid coding are explored. Large databases of genetic variants in healthy individuals and patients with a range of disorders, including hemophilia B, are yielding useful information on sequence variant frequency to help establish possible variant pathogenicity, and a growing range of algorithms are available to help predict pathogenicity for previously unreported variants.
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Affiliation(s)
- A C Goodeve
- Haemostasis Research Group, Department of Cardiovascular Science, Sheffield Children's NHS Foundation Trust, University of Sheffield and Sheffield Diagnostic Genetics Service, Sheffield, UK
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