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Watanabe K, Nishio SY, Usami SI. The prevalence and clinical features of MYO7A-related hearing loss including DFNA11, DFNB2 and USH1B. Sci Rep 2024; 14:8326. [PMID: 38594301 PMCID: PMC11003999 DOI: 10.1038/s41598-024-57415-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 03/18/2024] [Indexed: 04/11/2024] Open
Abstract
The MYO7A gene is known to be responsible for both syndromic hearing loss (Usher syndrome type1B:USH1B) and non-syndromic hearing loss including autosomal dominant and autosomal recessive inheritance (DFNA11, DFNB2). However, the prevalence and detailed clinical features of MYO7A-associated hearing loss across a large population remain unclear. In this study, we conducted next-generation sequencing analysis for a large cohort of 10,042 Japanese hearing loss patients. As a result, 137 patients were identified with MYO7A-associated hearing loss so that the prevalence among Japanese hearing loss patients was 1.36%. We identified 70 disease-causing candidate variants in this study, with 36 of them being novel variants. All variants identified in autosomal dominant cases were missense or in-frame deletion variants. Among the autosomal recessive cases, all patients had at least one missense variant. On the other hand, in patients with Usher syndrome, almost half of the patients carried biallelic null variants (nonsense, splicing, and frameshift variants). Most of the autosomal dominant cases showed late-onset progressive hearing loss. On the other hand, cases with autosomal recessive inheritance or Usher syndrome showed congenital or early-onset hearing loss. The visual symptoms in the Usher syndrome cases developed between age 5-15, and the condition was diagnosed at about 6-15 years of age.
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Affiliation(s)
- Kizuki Watanabe
- Department of Otorhinolaryngology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Japan
| | - Shin-Ya Nishio
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan
| | - Shin-Ichi Usami
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
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2
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Chen L, Hong M, Luan C, Gao H, Ru G, Guo X, Zhang D, Zhang S, Li C, Wu J, Randolph PB, Sousa AA, Qu C, Zhu Y, Guan Y, Wang L, Liu M, Feng B, Song G, Liu DR, Li D. Adenine transversion editors enable precise, efficient A•T-to-C•G base editing in mammalian cells and embryos. Nat Biotechnol 2024; 42:638-650. [PMID: 37322276 DOI: 10.1038/s41587-023-01821-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 05/08/2023] [Indexed: 06/17/2023]
Abstract
Base editors have substantial promise in basic research and as therapeutic agents for the correction of pathogenic mutations. The development of adenine transversion editors has posed a particular challenge. Here we report a class of base editors that enable efficient adenine transversion, including precise A•T-to-C•G editing. We found that a fusion of mouse alkyladenine DNA glycosylase (mAAG) with nickase Cas9 and deaminase TadA-8e catalyzed adenosine transversion in specific sequence contexts. Laboratory evolution of mAAG significantly increased A-to-C/T conversion efficiency up to 73% and expanded the targeting scope. Further engineering yielded adenine-to-cytosine base editors (ACBEs), including a high-accuracy ACBE-Q variant, that precisely install A-to-C transversions with minimal Cas9-independent off-targeting effects. ACBEs mediated high-efficiency installation or correction of five pathogenic mutations in mouse embryos and human cell lines. Founder mice showed 44-56% average A-to-C edits and allelic frequencies of up to 100%. Adenosine transversion editors substantially expand the capabilities and possible applications of base editing technology.
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Affiliation(s)
- Liang Chen
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Mengjia Hong
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Changming Luan
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Hongyi Gao
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Gaomeng Ru
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Xinyuan Guo
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Dujuan Zhang
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Shun Zhang
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Changwei Li
- Department of Orthopedics, Shanghai Key Laboratory for Prevention and Treatment of Bone and Joint Diseases with Integrated Chinese-Western Medicine, Shanghai Institute of Traumatology and Orthopedics, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Jun Wu
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Peyton B Randolph
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Cambridge, MA, USA
| | - Alexander A Sousa
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Cambridge, MA, USA
| | - Chao Qu
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Yifan Zhu
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Yuting Guan
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Liren Wang
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Mingyao Liu
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
- BRL Medicine, Inc., Shanghai, China
| | - Bo Feng
- School of Biomedical Sciences, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China
| | - Gaojie Song
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - David R Liu
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Cambridge, MA, USA
| | - Dali Li
- Shanghai Frontiers Science Center of Genome Editing and Cell Therapy, Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China.
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3
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Miyoshi T, Belyantseva IA, Sajeevadathan M, Friedman TB. Pathophysiology of human hearing loss associated with variants in myosins. Front Physiol 2024; 15:1374901. [PMID: 38562617 PMCID: PMC10982375 DOI: 10.3389/fphys.2024.1374901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 02/21/2024] [Indexed: 04/04/2024] Open
Abstract
Deleterious variants of more than one hundred genes are associated with hearing loss including MYO3A, MYO6, MYO7A and MYO15A and two conventional myosins MYH9 and MYH14. Variants of MYO7A also manifest as Usher syndrome associated with dysfunction of the retina and vestibule as well as hearing loss. While the functions of MYH9 and MYH14 in the inner ear are debated, MYO3A, MYO6, MYO7A and MYO15A are expressed in inner ear hair cells along with class-I myosin MYO1C and are essential for developing and maintaining functional stereocilia on the apical surface of hair cells. Stereocilia are large, cylindrical, actin-rich protrusions functioning as biological mechanosensors to detect sound, acceleration and posture. The rigidity of stereocilia is sustained by highly crosslinked unidirectionally-oriented F-actin, which also provides a scaffold for various proteins including unconventional myosins and their cargo. Typical myosin molecules consist of an ATPase head motor domain to transmit forces to F-actin, a neck containing IQ-motifs that bind regulatory light chains and a tail region with motifs recognizing partners. Instead of long coiled-coil domains characterizing conventional myosins, the tails of unconventional myosins have various motifs to anchor or transport proteins and phospholipids along the F-actin core of a stereocilium. For these myosins, decades of studies have elucidated their biochemical properties, interacting partners in hair cells and variants associated with hearing loss. However, less is known about how myosins traffic in a stereocilium using their motor function, and how each variant correlates with a clinical condition including the severity and onset of hearing loss, mode of inheritance and presence of symptoms other than hearing loss. Here, we cover the domain structures and functions of myosins associated with hearing loss together with advances, open questions about trafficking of myosins in stereocilia and correlations between hundreds of variants in myosins annotated in ClinVar and the corresponding deafness phenotypes.
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Affiliation(s)
- Takushi Miyoshi
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, United States
- Division of Molecular and Integrative Physiology, Department of Biomedical Sciences, Southern Illinois University School of Medicine, Carbondale, IL, United States
| | - Inna A. Belyantseva
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, United States
| | - Mrudhula Sajeevadathan
- Division of Molecular and Integrative Physiology, Department of Biomedical Sciences, Southern Illinois University School of Medicine, Carbondale, IL, United States
| | - Thomas B. Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, United States
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Peart L, Gonzalez J, Morel Swols D, Duman D, Saridogan T, Ramzan M, Zafeer MF, Liu XZ, Eshraghi AA, Hoffer ME, Angeli SI, Bademci G, Blanton S, Smith C, Telischi FF, Tekin M. Dispersed DNA variants underlie hearing loss in South Florida's minority population. Hum Genomics 2023; 17:103. [PMID: 37996878 PMCID: PMC10668374 DOI: 10.1186/s40246-023-00556-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 11/19/2023] [Indexed: 11/25/2023] Open
Abstract
BACKGROUND We analyzed the genetic causes of sensorineural hearing loss in racial and ethnic minorities of South Florida by reviewing demographic, phenotypic, and genetic data on 136 patients presenting to the Hereditary Hearing Loss Clinic at the University of Miami. In our retrospective chart review, of these patients, half self-identified as Hispanic, and the self-identified racial distribution was 115 (86%) White, 15 (11%) Black, and 6 (4%) Asian. Our analysis helps to reduce the gap in understanding the prevalence, impact, and genetic factors related to hearing loss among diverse populations. RESULTS The causative gene variant or variants were identified in 54 (40%) patients, with no significant difference in the molecular diagnostic rate between Hispanics and Non-Hispanics. However, the total solve rate based on race was 40%, 47%, and 17% in Whites, Blacks, and Asians, respectively. In Non-Hispanic Whites, 16 different variants were identified in 13 genes, with GJB2 (32%), MYO7A (11%), and SLC26A4 (11%) being the most frequently implicated genes. In White Hispanics, 34 variants were identified in 20 genes, with GJB2 (22%), MYO7A (7%), and STRC-CATSPER2 (7%) being the most common. In the Non-Hispanic Black cohort, the gene distribution was evenly dispersed, with 11 variants occurring in 7 genes, and no variant was identified in 3 Hispanic Black probands. For the Asian cohort, only one gene variant was found out of 6 patients. CONCLUSION This study demonstrates that the diagnostic rate of genetic studies in hearing loss varies according to race in South Florida, with more heterogeneity in racial and ethnic minorities. Further studies to delineate deafness gene variants in underrepresented populations, such as African Americans/Blacks from Hispanic groups, are much needed to reduce racial and ethnic disparities in genetic diagnoses.
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Affiliation(s)
- LéShon Peart
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Joanna Gonzalez
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Dayna Morel Swols
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Duygu Duman
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
- Department of Audiology, Faculty of Health Sciences, Ankara University, Ankara, Turkey
| | - Turcin Saridogan
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Memoona Ramzan
- Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Mohammad Faraz Zafeer
- Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Xue Zhong Liu
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
- Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL, USA
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Adrien A Eshraghi
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Michael E Hoffer
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Simon I Angeli
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Guney Bademci
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Susan Blanton
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
- Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL, USA
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Carson Smith
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Fred F Telischi
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Mustafa Tekin
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA.
- Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL, USA.
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, FL, USA.
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5
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Xiang Y, Xu C, Xu Y, Zhou L, Tang S, Xu X. Novel compound heterozygous synonymous and missense variants in the MYO7A gene identified by next-generation sequencing in a Chinese family with nonsyndromic hearing loss. J Clin Lab Anal 2022; 36:e24708. [PMID: 36164746 DOI: 10.1002/jcla.24708] [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: 07/12/2022] [Revised: 08/28/2022] [Accepted: 09/06/2022] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Variants in the MYO7A gene are increasingly identified among patients suffering from Usher syndrome type 1B (USH1B). However, such mutations are less commonly detected among patients suffering from nonsyndromic hearing loss (NSHL), including autosomal recessive deafness (DFNB2) and autosomal dominant deafness (DFNA11). This research attempts to clarify the genetic base of DFNB2 in a Chinese family and determine the pathogenicity of the identified mutations. METHOD Targeted next-generation sequencing (TGS) of 127 known deafness genes was performed for the 14-year-old proband. Then, Sanger sequencing was performed on the available family members. A minigene splicing assay was performed to verify the impact of the novel MYO7A synonymous variant. After performing targeted next-generation sequencing (TGS) of 127 existing hearing loss-related genes in a 14-year-old proband, Sanger sequencing was carried out on the available family members. Then, to confirm the influence of the novel MYO7A synonymous variants, a minigene splicing assay was performed. RESULTS Two heteroallelic mutants of MYO7A (NM_000260.3) were identified: a maternally inherited synonymous variant c.2904G > A (p.Glu968=) in exon 23 and a paternally inherited missense variant c.5994G > T (p.Trp1998Cys) in exon 44. The in vitro minigene expression indicated that c.2904G > A may result in skipping of exon 23 resulting in a truncated protein. CONCLUSIONS We reported a novel missense (c.5994G > T) and identified, for the first time, a novel pathogenic synonymous (c.2904G > A) variant within MYO7A in a patient with DFNB2. These findings enrich our understanding of the MYO7A variant spectrum of DFNB2 and can contribute to accurate genetic counseling and diagnosis of NSHL patients.
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Affiliation(s)
- Yanbao Xiang
- Department of Genetics, Key Laboratory of Birth Defects of Wenzhou, Wenzhou Central Hospital, Wenzhou, China
| | - Chenyang Xu
- Department of Genetics, Key Laboratory of Birth Defects of Wenzhou, Wenzhou Central Hospital, Wenzhou, China
| | - Yunzhi Xu
- Department of Genetics, Key Laboratory of Birth Defects of Wenzhou, Wenzhou Central Hospital, Wenzhou, China
| | - Lili Zhou
- Department of Genetics, Key Laboratory of Birth Defects of Wenzhou, Wenzhou Central Hospital, Wenzhou, China
| | - Shaohua Tang
- Department of Genetics, Key Laboratory of Birth Defects of Wenzhou, Wenzhou Central Hospital, Wenzhou, China.,Department of Clinical Laboratory Medicine, Key Laboratory of Precision Medicine of Wenzhou, Wenzhou Central Hospital, Wenzhou, China
| | - Xueqin Xu
- Department of Genetics, Key Laboratory of Birth Defects of Wenzhou, Wenzhou Central Hospital, Wenzhou, China.,Department of Clinical Laboratory Medicine, Key Laboratory of Precision Medicine of Wenzhou, Wenzhou Central Hospital, Wenzhou, China
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Kabahuma RI, Schubert W, Labuschagne C, Yan D, Pepper MS, Liu X. Elucidation of repeat motifs R1- and R2-related TRIOBP variants in autosomal recessive nonsyndromic hearing loss DFNB28 among indigenous South African individuals. Mol Genet Genomic Med 2022; 10:e2015. [PMID: 36029164 PMCID: PMC9544205 DOI: 10.1002/mgg3.2015] [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: 12/16/2021] [Revised: 06/10/2022] [Accepted: 06/28/2022] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND DFNB28, a recessively inherited nonsyndromic form of deafness in humans, is caused by mutations in the TRIOBP gene (MIM #609761) on chromosome 22q13. Its protein TRIOBP helps to tightly bundle F-actin filaments, forming a rootlet that penetrates through the cuticular plate into the cochlear hair cell body. Repeat motifs R1 and R2, located in exon 7 of the TRIOBP-5 isoform, are the actin-binding domains. Deletion of both repeat motifs R1 and R2 results in complete disruption of both actin-binding and bundling activities, whereas deletion of the R2 motif alone retains F-actin bundling ability in stereocilia rootlets. METHODS Target sequencing, using a custom capture panel of 180 known and candidate genes associated with sensorineural hearing loss, bioinformatics processing, and data analysis were performed. Genesis 2.0 was used for variant filtering based on quality/score read depth and minor allele frequency (MAF) thresholds of 0.005 for recessive NSHL, as reported in population-based sequencing databases. All variants were reclassified based on the American College of Medical Genetics and Genomics (ACMG) and Association for Molecular Pathology (AMP) guidelines together with other variant interpretation guidelines for genetic hearing loss . Candidate variants were confirmed via Sanger sequencing according to standard protocols, using the ABIPRISM 3730 DNA Analyzer. DNA sequence analysis was performed with DNASTAR Lasergene software. RESULTS Candidate TRIOBP variants identified among 94 indigenous sub-Saharan African individuals were characterized through segregation analysis. Family TS005 carrying variants c.572delC, p.Pro191Argfs*50, and c.3510_3513dupTGCA, p.Pro1172Cysfs*13, demonstrated perfect cosegregation with the deafness phenotype. On the other hand, variants c.505C > A p.Asp168Glu and c.3636 T > A p.Leu1212Gln in the same family did not segregate with deafness and we have classified these variants as benign. A control family, TS067, carrying variants c.2532G > T p.Leu844Arg, c.2590C > A p.Asn867Lys, c.3484C > T p.Pro1161Leu, and c.3621 T > C p.Phe1187Leu demonstrated no cosegregation allowing us to classify these variants as benign. Together with published TRIOBP variants, the results showed that genotypes combining two truncating TRIOBP variants affecting repeat motifs R1 and R2 or R2 alone lead to a deafness phenotype, while a truncating variant affecting repeat motifs R1 and R2 or R2 alone combined with a missense variant does not. Homozygous truncating variants affecting repeat motif R2 cosegregate with the deafness phenotype. CONCLUSION While a single intact R1 motif may be adequate for actin-binding and bundling in the stereocilia of cochlear hair cells, our findings indicate that a truncated R2 motif in cis seems to be incompatible with normal hearing, either by interfering with the function of an intact R1 motif or through another as yet unknown mechanism. Our study also suggests that most heterozygous missense variants involving exon 7 are likely to be tolerated.
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Affiliation(s)
- Rosemary Ida Kabahuma
- Department of OtorhinolaryngologyUniversity of PretoriaPretoriaSouth Africa,Departments of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural SciencesUniversity of PretoriaPretoriaSouth Africa
| | - Wolf‐Dieter Schubert
- Departments of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural SciencesUniversity of PretoriaPretoriaSouth Africa
| | | | - Denise Yan
- Department of OtolaryngologyUniversity of Miami Miller School of MedicineMiamiFloridaUSA
| | - Michael Sean Pepper
- Institute for Cellular and Molecular Medicine, Department of Immunology and SAMRC Extramural Unit for Stem Cell Research and Therapy, Faculty of Health SciencesUniversity of PretoriaPretoriaSouth Africa
| | - Xue‐Zhong Liu
- Department of OtolaryngologyUniversity of Miami Miller School of MedicineMiamiFloridaUSA
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Manyisa N, Adadey SM, Wonkam-Tingang E, Yalcouye A, Wonkam A. Hearing Impairment in South Africa and the Lessons Learned for Planetary Health Genomics: A Systematic Review. OMICS : A JOURNAL OF INTEGRATIVE BIOLOGY 2022; 26:2-18. [PMID: 35041532 PMCID: PMC8792495 DOI: 10.1089/omi.2021.0181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Hearing impairment (HI) is a silent planetary health crisis that requires attention worldwide. The prevalence of HI in South Africa is estimated as 5.5 in 100 live births, which is about 5 times higher than the prevalence in high-income countries. This also offers opportunity to drive progressive science, technology and innovation policy, and health systems. We present here a systematic analysis and review on the prevalence, etiologies, clinical patterns, and genetics/genomics of HI in South Africa. We searched PubMed, Scopus, African Journals Online, AFROLIB, and African Index Medicus to identify the pertinent studies on HI in South Africa, published from inception to April 30, 2021, and the data were summarized narratively. We screened 944 records, of which 27 studies were included in the review. The age at diagnosis is ∼3 years of age and the most common factor associated with acquired HI was middle ear infections. There were numerous reports on medication toxicity, with kanamycin-induced ototoxicity requiring specific attention when considering the high burden of tuberculosis in South Africa. The Waardenburg Syndrome is the most common reported syndromic HI. The Usher Syndrome is the only syndrome with genetic investigations, whereby a founder mutation was identified among black South Africans (MYO7A-c.6377delC). GJB2 and GJB6 genes are not major contributors to nonsyndromic HI among Black South Africans. Furthermore, emerging data using targeted panel sequencing have shown a low resolution rate in Black South Africans in known HI genes. Importantly, mutations in known nonsyndromic HI genes are infrequent in South Africa. Therefore, whole-exome sequencing appears as the most effective way forward to identify variants associated with HI in South Africa. Taken together, this article contributes to the emerging field of planetary health genomics with a focus on HI and offers new insights and lessons learned for future roadmaps on genomics/multiomics and clinical studies of HI around the world.
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Affiliation(s)
- Noluthando Manyisa
- Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Samuel Mawuli Adadey
- Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Edmond Wonkam-Tingang
- Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Abdoulaye Yalcouye
- Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Department of Neurology, Point G Teaching Hospital, University of Sciences, Techniques and Technology, Bamako, Mali
| | - Ambroise Wonkam
- Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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8
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Mansard L, Baux D, Vaché C, Blanchet C, Meunier I, Willems M, Faugère V, Baudoin C, Moclyn M, Bianchi J, Dollfus H, Gilbert-Dussardier B, Dupin-Deguine D, Bonneau D, Drumare I, Odent S, Zanlonghi X, Claustres M, Koenig M, Kalatzis V, Roux AF. The Study of a 231 French Patient Cohort Significantly Extends the Mutational Spectrum of the Two Major Usher Genes MYO7A and USH2A. Int J Mol Sci 2021; 22:ijms222413294. [PMID: 34948090 PMCID: PMC8703989 DOI: 10.3390/ijms222413294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/03/2021] [Accepted: 12/08/2021] [Indexed: 01/06/2023] Open
Abstract
Usher syndrome is an autosomal recessive disorder characterized by congenital hearing loss combined with retinitis pigmentosa, and in some cases, vestibular areflexia. Three clinical subtypes are distinguished, and MYO7A and USH2A represent the two major causal genes involved in Usher type I, the most severe form, and type II, the most frequent form, respectively. Massively parallel sequencing was performed on a cohort of patients in the context of a molecular diagnosis to confirm clinical suspicion of Usher syndrome. We report here 231 pathogenic MYO7A and USH2A genotypes identified in 73 Usher type I and 158 Usher type II patients. Furthermore, we present the ACMG classification of the variants, which comprise all types. Among them, 68 have not been previously reported in the literature, including 12 missense and 16 splice variants. We also report a new deep intronic variant in USH2A. Despite the important number of molecular studies published on these two genes, we show that during the course of routine genetic diagnosis, undescribed variants continue to be identified at a high rate. This is particularly pertinent in the current era, where therapeutic strategies based on DNA or RNA technologies are being developed.
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Affiliation(s)
- Luke Mansard
- Molecular Genetics Laboratory, University of Montpellier, CHU Montpellier, F-34000 Montpellier, France; (L.M.); (D.B.); (C.V.); (V.F.); (C.B.); (M.M.); (J.B.); (M.C.); (M.K.)
| | - David Baux
- Molecular Genetics Laboratory, University of Montpellier, CHU Montpellier, F-34000 Montpellier, France; (L.M.); (D.B.); (C.V.); (V.F.); (C.B.); (M.M.); (J.B.); (M.C.); (M.K.)
- Institute for Neurosciences of Montpellier (INM), University of Montpellier, Inserm, F-34000 Montpellier, France; (I.M.); (M.W.); (V.K.)
| | - Christel Vaché
- Molecular Genetics Laboratory, University of Montpellier, CHU Montpellier, F-34000 Montpellier, France; (L.M.); (D.B.); (C.V.); (V.F.); (C.B.); (M.M.); (J.B.); (M.C.); (M.K.)
- Institute for Neurosciences of Montpellier (INM), University of Montpellier, Inserm, F-34000 Montpellier, France; (I.M.); (M.W.); (V.K.)
| | - Catherine Blanchet
- National Reference Centre for Inherited Sensory Diseases, University Montpellier, CHU Montpellier, F-34000 Montpellier, France;
- Oto Laryngology Department, University of Montpellier, CHU Montpellier, F-34000 Montpellier, France
| | - Isabelle Meunier
- Institute for Neurosciences of Montpellier (INM), University of Montpellier, Inserm, F-34000 Montpellier, France; (I.M.); (M.W.); (V.K.)
- National Reference Centre for Inherited Sensory Diseases, University Montpellier, CHU Montpellier, F-34000 Montpellier, France;
| | - Marjolaine Willems
- Institute for Neurosciences of Montpellier (INM), University of Montpellier, Inserm, F-34000 Montpellier, France; (I.M.); (M.W.); (V.K.)
- Medical Genetics Department, University of Montpellier, CHU Montpellier, F-34000 Montpellier, France
| | - Valérie Faugère
- Molecular Genetics Laboratory, University of Montpellier, CHU Montpellier, F-34000 Montpellier, France; (L.M.); (D.B.); (C.V.); (V.F.); (C.B.); (M.M.); (J.B.); (M.C.); (M.K.)
| | - Corinne Baudoin
- Molecular Genetics Laboratory, University of Montpellier, CHU Montpellier, F-34000 Montpellier, France; (L.M.); (D.B.); (C.V.); (V.F.); (C.B.); (M.M.); (J.B.); (M.C.); (M.K.)
| | - Melody Moclyn
- Molecular Genetics Laboratory, University of Montpellier, CHU Montpellier, F-34000 Montpellier, France; (L.M.); (D.B.); (C.V.); (V.F.); (C.B.); (M.M.); (J.B.); (M.C.); (M.K.)
| | - Julie Bianchi
- Molecular Genetics Laboratory, University of Montpellier, CHU Montpellier, F-34000 Montpellier, France; (L.M.); (D.B.); (C.V.); (V.F.); (C.B.); (M.M.); (J.B.); (M.C.); (M.K.)
| | - Helene Dollfus
- Reference Center for Rare Affections in Ophthalmology Genetics (CARGO), Institute of Medical Genetics of Alsace, University of Strasbourg, CHU Strasbourg, F-67000 Strasbourg, France;
| | | | - Delphine Dupin-Deguine
- Medical Genetics Department, University of Toulouse, CHU Purpan, F-31000 Toulouse, France;
| | - Dominique Bonneau
- Medical Genetics Department, University of Angers, CHU Angers, F-49000 Angers, France;
| | - Isabelle Drumare
- Vision and Neuro-Ophthalmology Department, University of Lille, CHU Lille, F-59000 Lille, France;
| | - Sylvie Odent
- Clinical Genetics Service, University Hospital, Genetics and Development Institute of Rennes IDGDR, UMR6290 University of Rennes, F-35000 Rennes, France;
| | - Xavier Zanlonghi
- Center of Competence for Rare Diseases, Jules Verne Clinic, F-44000 Nantes, France;
| | - Mireille Claustres
- Molecular Genetics Laboratory, University of Montpellier, CHU Montpellier, F-34000 Montpellier, France; (L.M.); (D.B.); (C.V.); (V.F.); (C.B.); (M.M.); (J.B.); (M.C.); (M.K.)
| | - Michel Koenig
- Molecular Genetics Laboratory, University of Montpellier, CHU Montpellier, F-34000 Montpellier, France; (L.M.); (D.B.); (C.V.); (V.F.); (C.B.); (M.M.); (J.B.); (M.C.); (M.K.)
| | - Vasiliki Kalatzis
- Institute for Neurosciences of Montpellier (INM), University of Montpellier, Inserm, F-34000 Montpellier, France; (I.M.); (M.W.); (V.K.)
| | - Anne-Françoise Roux
- Molecular Genetics Laboratory, University of Montpellier, CHU Montpellier, F-34000 Montpellier, France; (L.M.); (D.B.); (C.V.); (V.F.); (C.B.); (M.M.); (J.B.); (M.C.); (M.K.)
- Institute for Neurosciences of Montpellier (INM), University of Montpellier, Inserm, F-34000 Montpellier, France; (I.M.); (M.W.); (V.K.)
- Correspondence:
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Adadey SM, Wonkam-Tingang E, Aboagye ET, Quaye O, Awandare GA, Wonkam A. Hearing loss in Africa: current genetic profile. Hum Genet 2021; 141:505-517. [PMID: 34609590 PMCID: PMC9034983 DOI: 10.1007/s00439-021-02376-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 09/21/2021] [Indexed: 01/03/2023]
Abstract
Hearing impairment (HI) is highly heterogeneous with over 123 associated genes reported to date, mostly from studies among Europeans and Asians. Here, we performed a systematic review of literature on the genetic profile of HI in Africa. The study protocol was registered on PROSPERO, International Prospective Register of Systematic Reviews with the registration number “CRD42021240852”. Literature search was conducted on PubMed, Scopus, Africa-Wide Information, and Web of Science databases. A total of 89 full-text records was selected and retrieved for data extraction and analyses. We found reports from only 17/54 (31.5%) African countries. The majority (61/89; 68.5%) of articles were from North Africa, with few reports found from sub-Saharan Africa. The most common method used in these publications was targeted gene sequencing (n = 66/111; 59.5%), and only 13.5% (n = 15/111) used whole-exome sequencing. More than half of the studies were performed in families segregating HI (n = 51/89). GJB2 was the most investigated gene, with GJB2: p.(R143W) founder variant only reported in Ghana, while GJB2: c.35delG was common in North African countries. Variants in MYO15A were the second frequently reported in both North and Central Africa, followed by ATP6V1B1 only reported from North Africa. Usher syndrome was the main syndromic HI molecularly investigated, with variants in five genes reported: USH2A, USH1G, USH1C, MYO7A, and PCDH15. MYO7A: p.(P1780S) founder variant was reported as the common Usher syndrome variant among Black South Africans. This review provides the most comprehensive data on HI gene variants in the largely under-investigated African populations. Future exomes studies particularly in multiplex families will likely provide opportunities for the discovery of the next sets of novel HI genes, and well as unreported variants in known genes to further our understanding of HI pathobiology, globally.
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Affiliation(s)
- Samuel Mawuli Adadey
- Department of Biochemistry, Cell and Molecular Biology, West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, P.O. Box LG 54, Legon, Accra, Ghana.,Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, Cape Town, 7925, South Africa
| | - Edmond Wonkam-Tingang
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, Cape Town, 7925, South Africa
| | - Elvis Twumasi Aboagye
- Department of Biochemistry, Cell and Molecular Biology, West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, P.O. Box LG 54, Legon, Accra, Ghana
| | - Osbourne Quaye
- Department of Biochemistry, Cell and Molecular Biology, West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, P.O. Box LG 54, Legon, Accra, Ghana
| | - Gordon A Awandare
- Department of Biochemistry, Cell and Molecular Biology, West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, P.O. Box LG 54, Legon, Accra, Ghana
| | - Ambroise Wonkam
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, Cape Town, 7925, South Africa.
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