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Miller CH. The Clinical Genetics of Hemophilia B (Factor IX Deficiency). Appl Clin Genet 2021; 14:445-454. [PMID: 34848993 PMCID: PMC8627312 DOI: 10.2147/tacg.s288256] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/26/2021] [Indexed: 12/28/2022] Open
Abstract
Hemophilia B (HB) is a bleeding disorder caused by deficiency of or defect in blood coagulation factor IX (FIX) inherited in an X-linked manner. It results from one of over 1000 known pathogenic variants in the FIX gene, F9; missense and frameshift changes predominate. Although primarily males are affected with HB, heterozygous females may have excessive bleeding due to random or non-random X chromosome inactivation; in addition, homozygous, compound heterozygous, and hemizygous females have been reported. Somatic and germinal mosaicism for F9 variants has been observed. Development of antibodies to FIX treatment products (inhibitors) is rare and related to the type of causative variant present. Treatment is with products produced by recombinant DNA technology, and gene therapy is in clinical trials. Genetic counseling with up-to-date information is warranted for heterozygotes, potential heterozygotes, and men and women affected with HB.
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Affiliation(s)
- Connie H Miller
- Division of Blood Disorders, National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, GA, USA
- Synergy America, Inc., Duluth, GA, USA
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Miller CH, Bean CJ. Genetic causes of haemophilia in women and girls. Haemophilia 2021; 27:e164-e179. [PMID: 33314404 PMCID: PMC8132474 DOI: 10.1111/hae.14186] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/07/2020] [Accepted: 10/19/2020] [Indexed: 01/19/2023]
Abstract
Women and girls reported as "haemophilic females" may have complex genetic causes for their haemophilia phenotype. In addition, women and girls may have excessive bleeding requiring treatment simply because they are heterozygous for haemophilia alleles. While severe and moderate haemophilia are rare in females, 16% of patients with mild haemophilia A and almost one-quarter of those with mild haemophilia B seen in U.S. haemophilia treatment centres are women and girls. A phenotypic female with a low level of factor VIII or factor IX may be classified into one of the following categories of causality: homozygosity (two identical haemophilia alleles), compound heterozygosity (two different haemophilia alleles), hemizygosity (one haemophilia allele and no normal allele), heterozygosity (one haemophilia allele and one normal allele), genetic causes other than haemophilia and non-genetic causes. Studies required for classification may include coagulation parameters, F8 or F9 sequencing, F8 inversion testing, multiplex ligation-dependent probe amplification, karyotyping and X chromosome inactivation studies performed on the patient and parents. Women and girls who are homozygous, compound heterozygous or hemizygous clearly have haemophilia, as they do not have a normal allele. Heterozygous women and girls with factor levels below the haemostatic range also meet the definitions used for haemophilia treatment.
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Affiliation(s)
- Connie H Miller
- Division of Blood Disorders, National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Christopher J Bean
- Division of Blood Disorders, National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, GA, USA
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Janczar S, Babol-Pokora K, Jatczak-Pawlik I, Taha J, Klukowska A, Laguna P, Windyga J, Odnoczko E, Zdziarska J, Iwaniec T, Koltan A, Jamrozik M, Rurańska I, Janczar K, Szczepański T, Pietrys D, Balwierz W, Treliński J, Mlynarski W. Six molecular patterns leading to hemophilia A phenotype in 18 females from Poland. Thromb Res 2020; 193:9-14. [PMID: 32497951 DOI: 10.1016/j.thromres.2020.05.041] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 04/12/2020] [Accepted: 05/26/2020] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Female hemophilia is an intriguing rare disorder and few larger reports on its genetic etiology are available. While historically the diagnosis was satisfactorily reached by factor VIII activity assays, the clinical and potentially therapeutic heterogeneity of female hemophilia calls for comprehensive molecular diagnosis in each case. Currently, the genetic investigations are not a part of routine, state-funded, diagnostics in Poland, and thus molecular epidemiological data are missing. AIM We set out to perform a comprehensive genetic analysis of Polish females with hemophilia A. PATIENTS/METHODS Eighteen females with hemophilia A (including 2 with severe and 5 with moderate hemophilia phenotype) consented for genetic diagnostics. To establish F8 mutations, we used next-generation sequencing of a panel of genes associated with hematological disorders, standard assays for recurrent intragenic F8 inversions and MLPA when deletions were suspected. When appropriate we also used karyotyping, genomic microarrays and X chromosome inactivation assays. RESULTS While abnormally skewed X-chromosome inactivation combined with a F8 variant on the active allele was, as expected, the most common genetic etiology, a number of other genetic scenarios were unraveled. This included: misdiagnosis (molecular diagnosis of vWd), Turner syndrome, compound heterozygosity and androgen insensitivity syndrome (a phenotypical 46,XY female with a novel androgen receptor gene mutation). We report 3 novel F8 mutations. CONCLUSION Every case of female hemophilia warrants full genomic diagnostics, as this may change the diagnosis or reveal broader morbidity than a coagulation disorder (Turner syndrome, androgen insensitivity, or cardiovascular morbidity that we described previously in a SHAM syndrome carrier).
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Affiliation(s)
- Szymon Janczar
- Department of Pediatrics, Oncology and Hematology, Medical University of Lodz, Poland.
| | | | | | - Joanna Taha
- Department of Pediatrics, Oncology and Hematology, Medical University of Lodz, Poland
| | - Anna Klukowska
- Department of Pediatrics, Hematology and Oncology, Warsaw Medical University, Poland
| | - Pawel Laguna
- Department of Pediatrics, Hematology and Oncology, Warsaw Medical University, Poland
| | - Jerzy Windyga
- Institute of Hematology and Transfusion Medicine in Warsaw, Poland
| | - Edyta Odnoczko
- Institute of Hematology and Transfusion Medicine in Warsaw, Poland
| | - Joanna Zdziarska
- Department of Hematology, Jagiellonian University, Krakow, Poland
| | - Teresa Iwaniec
- Department of Hematology, Jagiellonian University, Krakow, Poland
| | - Andrzej Koltan
- Department of Pediatrics, Hematology and Oncology, Nicolaus Copernicus University in Torun, Collegium Medicum in Bydgoszcz, Poland
| | - Michał Jamrozik
- Department of Hematology and Bone Marrow Transplantation, Medical University of Silesia, Katowice, Poland
| | - Iwona Rurańska
- Department of Pediatric Hematology and Oncology, Zabrze, Medical University of Silesia, Katowice, Poland
| | | | - Tomasz Szczepański
- Department of Pediatric Hematology and Oncology, Zabrze, Medical University of Silesia, Katowice, Poland
| | - Danuta Pietrys
- Department of Pediatric Oncology and Hematology, University Childrens' Hospital of Krakow, Poland
| | - Walentyna Balwierz
- Department of Pediatric Oncology and Hematology, University Childrens' Hospital of Krakow, Poland; Institute of Pediatrics, Jagiellonian University - Medical College, Krakow, Poland
| | - Jacek Treliński
- Department of Hemostasis, Medical University of Lodz, Poland
| | - Wojciech Mlynarski
- Department of Pediatrics, Oncology and Hematology, Medical University of Lodz, Poland
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