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Caliebe A, Tekola‐Ayele F, Darst BF, Wang X, Song YE, Gui J, Sebro RA, Balding DJ, Saad M, Dubé M. Including diverse and admixed populations in genetic epidemiology research. Genet Epidemiol 2022; 46:347-371. [PMID: 35842778 PMCID: PMC9452464 DOI: 10.1002/gepi.22492] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 05/31/2022] [Accepted: 06/06/2022] [Indexed: 11/25/2022]
Abstract
The inclusion of ancestrally diverse participants in genetic studies can lead to new discoveries and is important to ensure equitable health care benefit from research advances. Here, members of the Ethical, Legal, Social, Implications (ELSI) committee of the International Genetic Epidemiology Society (IGES) offer perspectives on methods and analysis tools for the conduct of inclusive genetic epidemiology research, with a focus on admixed and ancestrally diverse populations in support of reproducible research practices. We emphasize the importance of distinguishing socially defined population categorizations from genetic ancestry in the design, analysis, reporting, and interpretation of genetic epidemiology research findings. Finally, we discuss the current state of genomic resources used in genetic association studies, functional interpretation, and clinical and public health translation of genomic findings with respect to diverse populations.
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Affiliation(s)
- Amke Caliebe
- Institute of Medical Informatics and StatisticsKiel University and University Hospital Schleswig‐HolsteinKielGermany
| | - Fasil Tekola‐Ayele
- Epidemiology Branch, Division of Population Health Research, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMarylandUSA
| | - Burcu F. Darst
- Center for Genetic EpidemiologyUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
- Public Health Sciences DivisionFred Hutchinson Cancer Research CenterSeattleWashingtonUSA
| | - Xuexia Wang
- Department of MathematicsUniversity of North TexasDentonTexasUSA
| | - Yeunjoo E. Song
- Department of Population and Quantitative Health SciencesCase Western Reserve UniversityClevelandOhioUSA
| | - Jiang Gui
- Department of Biomedical Data Science, Geisel School of Medicine, Dartmouth CollegeOne Medical Center Dr.LebanonNew HampshireUSA
| | | | - David J. Balding
- Melbourne Integrative Genomics, Schools of BioSciences and of Mathematics & StatisticsUniversity of MelbourneMelbourneAustralia
| | - Mohamad Saad
- Qatar Computing Research InstituteHamad Bin Khalifa UniversityDohaQatar
- Neuroscience Research Center, Faculty of Medical SciencesLebanese UniversityBeirutLebanon
| | - Marie‐Pierre Dubé
- Department of Medicine, and Social and Preventive MedicineUniversité de MontréalMontréalQuébecCanada
- Beaulieu‐Saucier Pharmacogenomcis CentreMontreal Heart InstituteMontrealCanada
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Ju D, Hui D, Hammond DA, Wonkam A, Tishkoff SA. Importance of Including Non-European Populations in Large Human Genetic Studies to Enhance Precision Medicine. Annu Rev Biomed Data Sci 2022; 5:321-339. [PMID: 35576557 PMCID: PMC9904154 DOI: 10.1146/annurev-biodatasci-122220-112550] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
One goal of genomic medicine is to uncover an individual's genetic risk for disease, which generally requires data connecting genotype to phenotype, as done in genome-wide association studies (GWAS). While there may be clinical promise to employing prediction tools such as polygenic risk scores (PRS), it currently stands that individuals of non-European ancestry may not reap the benefits of genomic medicine because of underrepresentation in large-scale genetics studies. Here, we discuss why this inequity poses a problem for genomic medicine and the reasons for the low transferability of PRS across populations. We also survey the ancestry representation of published GWAS and investigate how estimates of ancestry diversity in GWASparticipants might be biased. We highlight the importance of expanding genetic research in Africa, one of the most underrepresented regions in human genomics research, and discuss issues of ethics, resources, and technology for equitable advancement of genomic medicine.
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Affiliation(s)
- Dan Ju
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA;
| | - Daniel Hui
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA;
- Graduate Program in Genomics and Computational Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Dorothy A Hammond
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA;
- Penn Center for Global Genomics & Health Equity, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ambroise Wonkam
- Division of Human Genetics, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
- Department of Genetic Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, USA;
| | - Sarah A Tishkoff
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA;
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Yalcouyé A, Esoh K, Guida L, Wonkam A. Current profile of Charcot-Marie-Tooth disease in Africa: A systematic review. J Peripher Nerv Syst 2022; 27:100-112. [PMID: 35383421 PMCID: PMC9322329 DOI: 10.1111/jns.12489] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 01/17/2022] [Accepted: 02/25/2022] [Indexed: 12/21/2022]
Abstract
BACKGROUND AND AIMS Charcot-Marie-Tooth disease (CMT) is the most common inherited peripheral neuropathy characterised by a high clinical and genetic heterogeneity. While most cases were described in populations with Caucasian ancestry, genetic research on CMT in Africa is scant. Only a few cases of CMT have been reported, mainly from North Africa. The current study aimed to summarise available data on CMT in Africa, with emphasis on the epidemiological, clinical, and genetic features. METHODS We searched PubMed, Scopus, Web of Sciences, and the African Journal Online for articles published from the database inception until April 2021 using specific keywords. A total of 398 articles were screened, and 28 fulfilled our selection criteria. RESULTS A total of 107 families totalling 185 patients were reported. Most studies were reported from North Africa (n = 22). The demyelinating form of CMT was the commonest subtype, and the phenotype varied greatly between families, and one family (1%) of CMT associated with hearing impairment was reported. The inheritance pattern was autosomal recessive in 91.2% (n = 97/107) of families. CMT-associated variants were reported in 11 genes: LMNA, GDAP1, GJB1, MPZ, MTMR13, MTMR2, PRX, FGD4/FRABIN, PMP22, SH3TC2, and GARS. The most common genes reported are LMNA, GDAP1, and SH3TC2 and have been found mostly in Northern African populations. INTERPRETATION This study reveals that CMT is not rare in Africa, and describes the current clinical and genetic profile. The review emphasised the urgent need to invest in genetic research to inform counselling, prevention, and care for CMT in numerous settings on the continent.
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Affiliation(s)
- Abdoulaye Yalcouyé
- Faculté de Médecine et d'Odontostomatologie, USTTB, Bamako, Mali.,Division of Human Genetics, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Kevin Esoh
- Division of Human Genetics, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Landouré Guida
- Faculté de Médecine et d'Odontostomatologie, USTTB, Bamako, Mali.,Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, USA.,Service de Neurologie, Centre Hospitalier Universitaire du Point "G", Bamako, Mali
| | - Ambroise Wonkam
- Division of Human Genetics, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,McKusick-Nathans Institute, and Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Wonkam A, Adadey SM, Schrauwen I, Aboagye ET, Wonkam-Tingang E, Esoh K, Popel K, Manyisa N, Jonas M, deKock C, Nembaware V, Cornejo Sanchez DM, Bharadwaj T, Nasir A, Everard JL, Kadlubowska MK, Nouel-Saied LM, Acharya A, Quaye O, Amedofu GK, Awandare GA, Leal SM. Exome sequencing of families from Ghana reveals known and candidate hearing impairment genes. Commun Biol 2022; 5:369. [PMID: 35440622 PMCID: PMC9019055 DOI: 10.1038/s42003-022-03326-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 03/25/2022] [Indexed: 12/15/2022] Open
Abstract
We investigated hearing impairment (HI) in 51 families from Ghana with at least two affected members that were negative for GJB2 pathogenic variants. DNA samples from 184 family members underwent whole-exome sequencing (WES). Variants were found in 14 known non-syndromic HI (NSHI) genes [26/51 (51.0%) families], five genes that can underlie either syndromic HI or NSHI [13/51 (25.5%)], and one syndromic HI gene [1/51 (2.0%)]. Variants in CDH23 and MYO15A contributed the most to HI [31.4% (16/51 families)]. For DSPP, an autosomal recessive mode of inheritance was detected. Post-lingual expression was observed for a family segregating a MARVELD2 variant. To our knowledge, seven novel candidate HI genes were identified (13.7%), with six associated with NSHI (INPP4B, CCDC141, MYO19, DNAH11, POTEI, and SOX9); and one (PAX8) with Waardenburg syndrome. MYO19 and DNAH11 were replicated in unrelated Ghanaian probands. Six of the novel genes were expressed in mouse inner ear. It is known that Pax8-/- mice do not respond to sound, and depletion of Sox9 resulted in defective vestibular structures and abnormal utricle development. Most variants (48/60; 80.0%) have not previously been associated with HI. Identifying seven candidate genes in this study emphasizes the potential of novel HI genes discovery in Africa.
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Affiliation(s)
- Ambroise Wonkam
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa.
- McKusick-Nathans Institute and Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
| | - Samuel Mawuli Adadey
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, LG 54, Ghana
| | - Isabelle Schrauwen
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Centre, New York, NY, 10032, USA
| | - Elvis Twumasi Aboagye
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, LG 54, Ghana
| | - Edmond Wonkam-Tingang
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa
| | - Kevin Esoh
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa
| | - Kalinka Popel
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa
| | - Noluthando Manyisa
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa
| | - Mario Jonas
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa
| | - Carmen deKock
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa
| | - Victoria Nembaware
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa
| | - Diana M Cornejo Sanchez
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Centre, New York, NY, 10032, USA
| | - Thashi Bharadwaj
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Centre, New York, NY, 10032, USA
| | - Abdul Nasir
- Department of Molecular Science and Technology, Ajou University, Suwon-si, Republic of Korea
| | - Jenna L Everard
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Centre, New York, NY, 10032, USA
| | - Magda K Kadlubowska
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Centre, New York, NY, 10032, USA
| | - Liz M Nouel-Saied
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Centre, New York, NY, 10032, USA
| | - Anushree Acharya
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Centre, New York, NY, 10032, USA
| | - Osbourne Quaye
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, LG 54, Ghana
| | - Geoffrey K Amedofu
- Department of Eye, Ear, Nose, and Throat, School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Gordon A Awandare
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, LG 54, Ghana
| | - Suzanne M Leal
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Centre, New York, NY, 10032, USA.
- Taub Institute for Alzheimer's Disease and the Aging Brain, Columbia University Medical Centre, New York, NY, 10032, USA.
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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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Han S, Zhang D, Guo Y, Fu Z, Guan G. Prevalence and Characteristics of STRC Gene Mutations (DFNB16): A Systematic Review and Meta-Analysis. Front Genet 2021; 12:707845. [PMID: 34621290 PMCID: PMC8491653 DOI: 10.3389/fgene.2021.707845] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 08/13/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Mutations in the STRC (MIM 606440) gene, inducing DFNB16, are considered a major cause of mild–moderate autosomal recessive non-syndromic hearing loss (ARNSHL). We conducted a systematic review and meta-analysis to determine the global prevalence and characteristics of STRC variations, important information required for genetic counseling. Methods: PubMed, Google Scholar, Medline, Embase, and Web of Science were searched for relevant articles published before January 2021. Results: The pooled prevalence of DFNB16 in GJB2-negative patients with hearing loss was 4.08% (95% CI: 0.0289–0.0573), and the proportion of STRC variants in the mild–moderate hearing loss group was 14.36%. Monoallelic mutations of STRC were 4.84% (95% CI: 0.0343–0.0680) in patients with deafness (non-GJB2) and 1.36% (95% CI: 0.0025–0.0696) in people with normal hearing. The DFNB16 prevalence in genetically confirmed patients (non-GJB2) was 11.10% (95% CI: 0.0716–0.1682). Overall pooled prevalence of deafness–infertility syndrome (DIS) was 36.75% (95% CI: 0.2122–0.5563) in DFNB16. The prevalence of biallelic deletions in STRC gene mutations was 70.85% (95% CI: 0.5824–0.8213). Conclusion: Variants in the STRC gene significantly contribute to mild–moderate hearing impairment. Moreover, biallelic deletions are a main feature of STRC mutations. Copy number variations associated with infertility should be seriously considered when investigating DFNB16.
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Affiliation(s)
- Shuang Han
- Department of Otolaryngology Head and Neck Surgery, The Second Hospital of Jilin University, Changchun, China
| | - Dejun Zhang
- Department of Otolaryngology Head and Neck Surgery, The Second Hospital of Jilin University, Changchun, China
| | - Yingyuan Guo
- Department of Otolaryngology Head and Neck Surgery, The Second Hospital of Jilin University, Changchun, China
| | - Zeming Fu
- Department of Otolaryngology Head and Neck Surgery, The Second Hospital of Jilin University, Changchun, China
| | - Guofang Guan
- Department of Otolaryngology Head and Neck Surgery, The Second Hospital of Jilin University, Changchun, China
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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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Kamp M, Krause A, Ramsay M. Has translational genomics come of age in Africa? Hum Mol Genet 2021; 30:R164-R173. [PMID: 34240178 DOI: 10.1093/hmg/ddab180] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/27/2021] [Accepted: 06/29/2021] [Indexed: 01/12/2023] Open
Abstract
The rapid increase in genomics research in Africa and the growing promise of precision public health begs the question of whether African genomics has come of age and is being translated into improved healthcare for Africans. An assessment of the continent's readiness suggests that genetic service delivery remains limited and extremely fragile. The paucity of data on mutation profiles for monogenic disorders and lack of large genome-wide association cohorts for complex traits in African populations is a significant barrier, coupled with extreme genetic variation across different regions and ethnic groups. Data from many different populations is essential to developing appropriate genetic services. Of the proposed genetic service delivery models currently used in Africa-Uncharacterized, Limited, Disease-focused, Emerging and Established-the first three best describe the situation in most African countries. Implementation is fraught with difficulties related to the scarcity of an appropriately skilled medical genetic workforce, limited infrastructure and processes, insufficient health funding and lack of political support, and overstretched health systems. There is a strong nucleus of determined and optimistic clinicians and scientists with a clear vision, and there is hope for innovative solutions and technological leapfrogging. However, a multi-dimensional approach with active interventions to stimulate genomic research, clinical genetics and overarching healthcare systems is needed to reduce genetic service inequalities and accelerate precision public health on the continent. Human and infrastructure capacity development, dedicated funding, political will and supporting legislation, and public education and awareness, are critical elements for success. Africa-relevant genomic and related health economics research remains imperative with an overarching need to translate knowledge into improved healthcare. Given the limited data and genetic services across most of Africa, the continent has not yet come of 'genomics' age.
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Affiliation(s)
- Michelle Kamp
- Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, The University of the Witwatersrand, National Health Laboratory Service, Johannesburg, 2193, South Africa.,Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2193, South Africa
| | - Amanda Krause
- Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, The University of the Witwatersrand, National Health Laboratory Service, Johannesburg, 2193, South Africa
| | - Michèle Ramsay
- Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, The University of the Witwatersrand, National Health Laboratory Service, Johannesburg, 2193, South Africa.,Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2193, South Africa
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9
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African genetic diversity and adaptation inform a precision medicine agenda. Nat Rev Genet 2021; 22:284-306. [PMID: 33432191 DOI: 10.1038/s41576-020-00306-8] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2020] [Indexed: 01/29/2023]
Abstract
The deep evolutionary history of African populations, since the emergence of modern humans more than 300,000 years ago, has resulted in high genetic diversity and considerable population structure. Selected genetic variants have increased in frequency due to environmental adaptation, but recent exposures to novel pathogens and changes in lifestyle render some of them with properties leading to present health liabilities. The unique discoverability potential from African genomic studies promises invaluable contributions to understanding the genomic and molecular basis of health and disease. Globally, African populations are understudied, and precision medicine approaches are largely based on data from European and Asian-ancestry populations, which limits the transferability of findings to the continent of Africa. Africa needs innovative precision medicine solutions based on African data that use knowledge and implementation strategies aligned to its climatic, cultural, economic and genomic diversity.
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Wonkam-Tingang E, Schrauwen I, Esoh KK, Bharadwaj T, Nouel-Saied LM, Acharya A, Nasir A, Leal SM, Wonkam A. A novel variant in DMXL2 gene is associated with autosomal dominant non-syndromic hearing impairment (DFNA71) in a Cameroonian family. Exp Biol Med (Maywood) 2021; 246:1524-1532. [PMID: 33715530 DOI: 10.1177/1535370221999746] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Approximately half of congenital hearing impairment cases are inherited, with non-syndromic hearing impairment (NSHI) being the most frequent clinical entity of genetic hearing impairment cases. A family from Cameroon with NSHI was investigated by performing exome sequencing using DNA samples obtained from three family members, followed by direct Sanger sequencing in additional family members and controls participants. We identified an autosomal dominantly inherited novel missense variant [NM_001174116.2:c.918G>T; p.(Q306H)] in DMXL2 gene (MIM:612186) that co-segregates with mild to profound non-syndromic sensorineural hearing impairment . The p.(Q306H) variant which substitutes a highly conserved glutamine residue is predicted deleterious by various bioinformatics tools and is absent from several genome databases. This variant was also neither found in 121 apparently healthy controls without a family history of hearing impairment , nor 112 sporadic NSHI cases from Cameroon. There is one previous report of a large Han Chinese NSHI family that segregates a missense variant in DMXL2. The present study provides additional evidence that DMXL2 is involved in hearing impairment etiology, and we suggest DMXL2 should be considered in diagnostic hearing impairment panels.
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Affiliation(s)
- Edmond Wonkam-Tingang
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa
| | - Isabelle Schrauwen
- Center for Statistical Genetics, Sergievsky Center, Taub Institute for Alzheimer's Disease and the Aging Brain, and the Department of Neurology, Columbia University Medical Centre, New York, NY 10032, USA
| | - Kevin K Esoh
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa
| | - Thashi Bharadwaj
- Center for Statistical Genetics, Sergievsky Center, Taub Institute for Alzheimer's Disease and the Aging Brain, and the Department of Neurology, Columbia University Medical Centre, New York, NY 10032, USA
| | - Liz M Nouel-Saied
- Center for Statistical Genetics, Sergievsky Center, Taub Institute for Alzheimer's Disease and the Aging Brain, and the Department of Neurology, Columbia University Medical Centre, New York, NY 10032, USA
| | - Anushree Acharya
- Center for Statistical Genetics, Sergievsky Center, Taub Institute for Alzheimer's Disease and the Aging Brain, and the Department of Neurology, Columbia University Medical Centre, New York, NY 10032, USA
| | - Abdul Nasir
- Synthetic Protein Engineering Lab (SPEL), Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea
| | - Suzanne M Leal
- Center for Statistical Genetics, Sergievsky Center, Taub Institute for Alzheimer's Disease and the Aging Brain, and the Department of Neurology, Columbia University Medical Centre, New York, NY 10032, USA
| | - Ambroise Wonkam
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa
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11
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Wonkam A, Lebeko K, Mowla S, Noubiap JJ, Chong M, Pare G. Whole exome sequencing reveals a biallelic frameshift mutation in GRXCR2 in hearing impairment in Cameroon. Mol Genet Genomic Med 2021; 9:e1609. [PMID: 33528103 PMCID: PMC8104159 DOI: 10.1002/mgg3.1609] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 01/06/2021] [Accepted: 01/11/2021] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Hearing impairment (HI) genes are poorly studied in African populations. METHODS We used whole exome sequencing (WES) to investigate pathogenic and likely pathogenic (PLP) variants in 10 individuals with HI, from four multiplex families from Cameroon, two of which were previously unresolved with a targeted gene enrichment (TGE) panel of 116 genes. In silico protein modelling, western blotting and live imaging of transfected HEK293 cells were performed to study protein structure and functions. RESULTS All PLP variants previously identified with TGE were replicated. In one previously unresolved family, we found a homozygous frameshift PLP variant in GRXCR2 (OMIM: 615762), NM_001080516.1(GRXCR2):c.251delC p.(Ile85SerfsTer33), in two affected siblings; and additionally, in 1/80 unrelated individuals affected with non-syndromic hearing impairment (NSHI). The GRXCR2-c.251delC variant introduced a premature stop codon, leading to truncation and loss of a zinc-finger domain. Fluorescence confocal microscopy tracked the wild-type GRXCR2 protein to the cellular membrane, unlike the mutated GRXCR2 protein. CONCLUSION This study confirms GRXCR2 as a HI-associated gene. GRXCR2 should be included to the currently available TGE panels for HI diagnosis.
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Affiliation(s)
- Ambroise Wonkam
- Department of Medicine, Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Institute of Infectious Diseases and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Kamogelo Lebeko
- Department of Medicine, Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Shaheen Mowla
- Department of Pathology, Division of Haematology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Jean Jacques Noubiap
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute (SAHMRI, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Mike Chong
- Population Health Research Institute, Hamilton Health Sciences and McMaster University, Hamilton, ON, Canada
| | - Guillaume Pare
- Population Health Research Institute, Hamilton Health Sciences and McMaster University, Hamilton, ON, Canada
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12
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Wonkam-Tingang E, Schrauwen I, Esoh KK, Bharadwaj T, Nouel-Saied LM, Acharya A, Nasir A, Adadey SM, Mowla S, Leal SM, Wonkam A. Bi-Allelic Novel Variants in CLIC5 Identified in a Cameroonian Multiplex Family with Non-Syndromic Hearing Impairment. Genes (Basel) 2020; 11:genes11111249. [PMID: 33114113 PMCID: PMC7690789 DOI: 10.3390/genes11111249] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/20/2020] [Accepted: 10/20/2020] [Indexed: 11/16/2022] Open
Abstract
DNA samples from five members of a multiplex non-consanguineous Cameroonian family, segregating prelingual and progressive autosomal recessive non-syndromic sensorineural hearing impairment, underwent whole exome sequencing. We identified novel bi-allelic compound heterozygous pathogenic variants in CLIC5. The variants identified, i.e., the missense [NM_016929.5:c.224T>C; p.(L75P)] and the splicing (NM_016929.5:c.63+1G>A), were validated using Sanger sequencing in all seven available family members and co-segregated with hearing impairment (HI) in the three hearing impaired family members. The three affected individuals were compound heterozygous for both variants, and all unaffected individuals were heterozygous for one of the two variants. Both variants were absent from the genome aggregation database (gnomAD), the Single Nucleotide Polymorphism Database (dbSNP), and the UK10K and Greater Middle East (GME) databases, as well as from 122 apparently healthy controls from Cameroon. We also did not identify these pathogenic variants in 118 unrelated sporadic cases of non-syndromic hearing impairment (NSHI) from Cameroon. In silico analysis showed that the missense variant CLIC5-p.(L75P) substitutes a highly conserved amino acid residue (leucine), and is expected to alter the stability, the structure, and the function of the CLIC5 protein, while the splicing variant CLIC5-(c.63+1G>A) is predicted to disrupt a consensus donor splice site and alter the splicing of the pre-mRNA. This study is the second report, worldwide, to describe CLIC5 involvement in human hearing impairment, and thus confirms CLIC5 as a novel non-syndromic hearing impairment gene that should be included in targeted diagnostic gene panels.
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Affiliation(s)
- Edmond Wonkam-Tingang
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa; (E.W.-T.); (K.K.E.); (S.M.A.)
| | - Isabelle Schrauwen
- Center for Statistical Genetics, Sergievsky Center, Taub Institute for Alzheimer’s Disease and the Aging Brain, and the Department of Neurology, Columbia University Medical Centre, New York, NY 10032, USA; (I.S.); (T.B.); (L.M.N.-S.); (A.A.); (S.M.L.)
| | - Kevin K. Esoh
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa; (E.W.-T.); (K.K.E.); (S.M.A.)
| | - Thashi Bharadwaj
- Center for Statistical Genetics, Sergievsky Center, Taub Institute for Alzheimer’s Disease and the Aging Brain, and the Department of Neurology, Columbia University Medical Centre, New York, NY 10032, USA; (I.S.); (T.B.); (L.M.N.-S.); (A.A.); (S.M.L.)
| | - Liz M. Nouel-Saied
- Center for Statistical Genetics, Sergievsky Center, Taub Institute for Alzheimer’s Disease and the Aging Brain, and the Department of Neurology, Columbia University Medical Centre, New York, NY 10032, USA; (I.S.); (T.B.); (L.M.N.-S.); (A.A.); (S.M.L.)
| | - Anushree Acharya
- Center for Statistical Genetics, Sergievsky Center, Taub Institute for Alzheimer’s Disease and the Aging Brain, and the Department of Neurology, Columbia University Medical Centre, New York, NY 10032, USA; (I.S.); (T.B.); (L.M.N.-S.); (A.A.); (S.M.L.)
| | - Abdul Nasir
- Synthetic Protein Engineering Lab (SPEL), Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea;
| | - Samuel M. Adadey
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa; (E.W.-T.); (K.K.E.); (S.M.A.)
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra LG 54, Ghana
| | - Shaheen Mowla
- Division of Haematology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa;
| | - Suzanne M. Leal
- Center for Statistical Genetics, Sergievsky Center, Taub Institute for Alzheimer’s Disease and the Aging Brain, and the Department of Neurology, Columbia University Medical Centre, New York, NY 10032, USA; (I.S.); (T.B.); (L.M.N.-S.); (A.A.); (S.M.L.)
| | - Ambroise Wonkam
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa; (E.W.-T.); (K.K.E.); (S.M.A.)
- Correspondence: ; Tel.: +27-21-4066-307
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Wonkam A, Manyisa N, Bope CD, Dandara C, Chimusa ER. Whole exome sequencing reveals pathogenic variants in MYO3A, MYO15A and COL9A3 and differential frequencies in ancestral alleles in hearing impairment genes among individuals from Cameroon. Hum Mol Genet 2020; 29:3729-3743. [PMID: 33078831 PMCID: PMC7861016 DOI: 10.1093/hmg/ddaa225] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 10/01/2020] [Accepted: 10/12/2020] [Indexed: 12/30/2022] Open
Abstract
There is scarcity of known gene variants of hearing impairment (HI) in African populations. This knowledge deficit is ultimately affecting the development of genetic diagnoses. We used whole exome sequencing to investigate gene variants, pathways of interactive genes and the fractions of ancestral overderived alleles for 159 HI genes among 18 Cameroonian patients with non-syndromic HI (NSHI) and 129 ethnically matched controls. Pathogenic and likely pathogenic (PLP) variants were found in MYO3A, MYO15A and COL9A3, with a resolution rate of 50% (9/18 patients). The study identified significant genetic differentiation in novel population-specific gene variants at FOXD4L2, DHRS2L6, RPL3L and VTN between HI patients and controls. These gene variants are found in functional/co-expressed interactive networks with other known HI-associated genes and in the same pathways with VTN being a hub protein, that is, focal adhesion pathway and regulation of the actin cytoskeleton (P-values <0.05). The results suggest that these novel population-specific gene variants are possible modifiers of the HI phenotypes. We found a high proportion of ancestral allele versus derived at low HI patients-specific minor allele frequency in the range of 0.0–0.1. The results showed a relatively low pickup rate of PLP variants in known genes in this group of Cameroonian patients with NSHI. In addition, findings may signal an evolutionary enrichment of some variants of HI genes in patients, as the result of polygenic adaptation, and suggest the possibility of multigenic influence on the phenotype of congenital HI, which deserves further investigations.
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Affiliation(s)
- Ambroise Wonkam
- Division of Human Genetics, Department of Pathology, University of Cape Town, Cape Town 7925, South Africa.,Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa
| | - Noluthando Manyisa
- Division of Human Genetics, Department of Pathology, University of Cape Town, Cape Town 7925, South Africa
| | - Christian D Bope
- Department of Mathematics and Department of Computer Science, Faculty of Sciences, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Collet Dandara
- Division of Human Genetics, Department of Pathology, University of Cape Town, Cape Town 7925, South Africa
| | - Emile R Chimusa
- Division of Human Genetics, Department of Pathology, University of Cape Town, Cape Town 7925, South Africa
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Abstract
In celebration of the 20th anniversary of Nature Reviews Genetics, we asked 12 leading researchers to reflect on the key challenges and opportunities faced by the field of genetics and genomics. Keeping their particular research area in mind, they take stock of the current state of play and emphasize the work that remains to be done over the next few years so that, ultimately, the benefits of genetic and genomic research can be felt by everyone. To celebrate the first 20 years of Nature Reviews Genetics, we asked 12 leading scientists to reflect on the key challenges and opportunities faced by the field of genetics and genomics. Amy L. McGuire is the Leon Jaworski Professor of Biomedical Ethics and Director of the Center for Medical Ethics and Health Policy at Baylor College of Medicine. She has received numerous teaching awards at Baylor College of Medicine, was recognized by the Texas Executive Women as a Woman on the Move in 2016 and was invited to give a TedMed talk titled “There is No Genome for the Human Spirit” in 2014. In 2020, she was elected as a Hastings Center Fellow. Her research focuses on ethical and policy issues related to emerging technologies, with a particular focus on genomic research, personalized medicine and the clinical integration of novel neurotechnologies. Stacey Gabriel is the Senior Director of the Genomics Platform at the Broad Institute since 2012 and has led platform development, execution and operation since its founding. She is Chair of Institute Scientists and serves on the institute’s executive leadership team. She is widely recognized as a leader in genomic technology and project execution. She has led the Broad’s contributions to numerous flagship projects in human genetics, including the International HapMap Project, the 1000 Genomes Project, The Cancer Genome Atlas, the National Heart, Lung, and Blood Institute’s Exome Sequencing Project and the TOPMed programme. She is Principal Investigator of the Broad’s All of Us (AoU) Genomics Center and serves on the AoU Program Steering Committee. Sarah A. Tishkoff is the David and Lyn Silfen University Associate Professor in Genetics and Biology at the University of Pennsylvania, Philadelphia, USA, and holds appointments in the School of Medicine and the School of Arts and Sciences. She is a member of the US National Academy of Sciences and a recipient of an NIH Pioneer Award, a David and Lucile Packard Career Award, a Burroughs/Wellcome Fund Career Award and an American Society of Human Genetics Curt Stern Award. Her work focuses on genomic variation in Africa, human evolutionary history, the genetic basis of adaptation and phenotypic variation in Africa, and the genetic basis of susceptibility to infectious disease in Africa. Ambroise Wonkam is Professor of Medical Genetics, Director of GeneMAP (Genetic Medicine of African Populations Research Centre) and Deputy Dean Research in the Faculty of Health Sciences, University of Cape Town, South Africa. He has successfully led numerous NIH- and Wellcome Trust-funded projects over the past decade to investigate clinical variability in sickle cell disease, hearing impairment genetics and the return of individual findings in genetic research in Africa. He won the competitive Clinical Genetics Society International Award for 2014 from the British Society of Genetic Medicine. He is president of the African Society of Human Genetics. Aravinda Chakravarti is Director of the Center for Human Genetics and Genomics, the Muriel G. and George W. Singer Professor of Neuroscience and Physiology, and Professor of Medicine at New York University School of Medicine. He is an elected member of the US National Academy of Sciences, the US National Academy of Medicine and the Indian National Science Academy. He has been a key participant in the Human Genome Project, the International HapMap Project and the 1000 Genomes Project. His research attempts to understand the molecular basis of multifactorial disease. He was awarded the 2013 William Allan Award by the American Society of Human Genetics and the 2018 Chen Award by the Human Genome Organization. Eileen E. M. Furlong is Head of the Genome Biology Department at the European Molecular Biology Laboratory (EMBL) and a member of the EMBL Directorate. She is an elected member of the European Molecular Biology Organization (EMBO) and the Academia Europaea, and a European Research Council (ERC) advanced investigator. Her group dissects fundamental principles of how the genome is regulated and how it drives cell fate decisions during embryonic development, including how developmental enhancers are organized and function within the 3D nucleus. Her work combines genetics, (single-cell) genomics, imaging and computational approaches to understand these processes. Her research has advanced the development of genomic methods for use in complex multicellular organisms. Barbara Treutlein is Associate Professor of Quantitative Developmental Biology in the Department of Biosystems Science and Engineering of ETH Zurich in Basel, Switzerland. Her group uses and develops single-cell genomics approaches in combination with stem cell-based 2D and 3D culture systems to study how human organs develop and regenerate and how cell fate is regulated. For her work, Barbara has received multiple awards, including the Friedmund Neumann Prize of the Schering Foundation, the Dr. Susan Lim Award for Outstanding Young Investigator of the International Society of Stem Cell Research and the EMBO Young Investigator Award. Alexander Meissner is a scientific member of the Max Planck Society and currently Managing Director of the Max Planck Institute (MPI) for Molecular Genetics in Berlin, Germany. He heads the Department of Genome Regulation and is a visiting scientist in the Department of Stem Cell and Regenerative Biology at Harvard University. Before his move to the MPI, he was a tenured professor at Harvard University and a senior associate member of the Broad Institute, where he co-directed the epigenomics programme. In 2018, he was elected as an EMBO member. His laboratory uses genomic tools to study developmental and disease biology with a particular focus on epigenetic regulation. Howard Y. Chang is the Virginia and D. K. Ludwig Professor of Cancer Genomics at Stanford University and an investigator at the Howard Hughes Medical Institute. He is a physician–scientist who has focused on deciphering the hidden information in the non-coding genome. His laboratory is best known for studies of long non-coding RNAs in gene regulation and development of new epigenomic technologies. He is an elected member of the US National Academy of Sciences, the US National Academy of Medicine, and the American Academy of Arts and Sciences. Núria López-Bigas is ICREA research Professor at the Institute for Research in Biomedicine and Associate Professor at the University Pompeu Fabra. She obtained an ERC Consolidator Grant in 2015 and was elected as an EMBO member in 2016. Her work has been recognized with the prestigious Banc de Sabadell Award for Research in Biomedicine, the Catalan National Award for Young Research Talent and the Career Development Award from the Human Frontier Science Program. Her research focuses on the identification of cancer driver mutations, genes and pathways across tumour types and in understanding the mutational processes that lead to the accumulation of mutations in cancer cells. Eran Segal is Professor in the Department of Computer Science and Applied Mathematics at the Weizmann Institute of Science, heading a multidisciplinary laboratory with extensive experience in machine learning, computational biology and analysis of heterogeneous high-throughput genomic data. His research focuses on the microbiome, nutrition and genetics, and their effect on health and disease and aims to develop personalized medicine based on big data from human cohorts. He has published more than 150 publications and received several awards and honours for his work, including the Overton and the Michael Bruno awards. He was recently elected as an EMBO member and as a member of the Israel Young Academy. Jin-Soo Kim is Director of the Center for Genome Engineering in the Institute for Basic Science in Daejon, South Korea. He has received numerous awards, including the 2017 Asan Award in Medicine, the 2017 Yumin Award in Science and the 2019 Research Excellence Award (Federation of Asian and Oceanian Biochemists and Molecular Biologists). He was featured as one of ten Science Stars of East Asia in Nature (558, 502–510 (2018)) and has been recognized as a highly cited researcher by Clarivate Analytics since 2018. His work focuses on developing tools for genome editing in biomedical research.
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Abstract
The incidence of hearing impairment (HI) is higher in low- and middle-income countries when compared to high-income countries. There is therefore a necessity to estimate the burden of this condition in developing world. The aim of our study was to use a systematic approach to provide summarized data on the prevalence, etiologies, clinical patterns and genetics of HI in Cameroon. We searched PubMed, Scopus, African Journals Online, AFROLIB and African Index Medicus to identify relevant studies on HI in Cameroon, published from inception to 31 October, 2019, with no language restrictions. Reference lists of included studies were also scrutinized, and data were summarized narratively. This study is registered with PROSPERO, number CRD42019142788. We screened 333 records, of which 17 studies were finally included in the review. The prevalence of HI in Cameroon ranges from 0.9% to 3.6% in population-based studies and increases with age. Environmental factors contribute to 52.6% to 62.2% of HI cases, with meningitis, impacted wax and age-related disorder being the most common ones. Hereditary HI comprises 0.8% to 14.8% of all cases. In 32.6% to 37% of HI cases, the origin remains unknown. Non-syndromic hearing impairment (NSHI) is the most frequent clinical entity and accounts for 86.1% to 92.5% of cases of HI of genetic origin. Waardenburg and Usher syndromes account for 50% to 57.14% and 8.9% to 42.9% of genetic syndromic cases, respectively. No pathogenic mutation was described in GJB6 gene, and the prevalence of pathogenic mutations in GJB2 gene ranged from 0% to 0.5%. The prevalence of pathogenic mutations in other known NSHI genes was <10% in Cameroonian probands. Environmental factors are the leading etiology of HI in Cameroon, and mutations in most important HI genes are infrequent in Cameroon. Whole genome sequencing therefore appears as the most effective way to identify variants associated with HI in Cameroon and sub-Saharan Africa in general.
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Wonkam Tingang E, Noubiap JJ, F. Fokouo JV, Oluwole OG, Nguefack S, Chimusa ER, Wonkam A. Hearing Impairment Overview in Africa: the Case of Cameroon. Genes (Basel) 2020; 11:genes11020233. [PMID: 32098311 PMCID: PMC7073999 DOI: 10.3390/genes11020233] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 02/15/2020] [Accepted: 02/19/2020] [Indexed: 01/27/2023] Open
Abstract
The incidence of hearing impairment (HI) is higher in low- and middle-income countries when compared to high-income countries. There is therefore a necessity to estimate the burden of this condition in developing world. The aim of our study was to use a systematic approach to provide summarized data on the prevalence, etiologies, clinical patterns and genetics of HI in Cameroon. We searched PubMed, Scopus, African Journals Online, AFROLIB and African Index Medicus to identify relevant studies on HI in Cameroon, published from inception to 31 October, 2019, with no language restrictions. Reference lists of included studies were also scrutinized, and data were summarized narratively. This study is registered with PROSPERO, number CRD42019142788. We screened 333 records, of which 17 studies were finally included in the review. The prevalence of HI in Cameroon ranges from 0.9% to 3.6% in population-based studies and increases with age. Environmental factors contribute to 52.6% to 62.2% of HI cases, with meningitis, impacted wax and age-related disorder being the most common ones. Hereditary HI comprises 0.8% to 14.8% of all cases. In 32.6% to 37% of HI cases, the origin remains unknown. Non-syndromic hearing impairment (NSHI) is the most frequent clinical entity and accounts for 86.1% to 92.5% of cases of HI of genetic origin. Waardenburg and Usher syndromes account for 50% to 57.14% and 8.9% to 42.9% of genetic syndromic cases, respectively. No pathogenic mutation was described in GJB6 gene, and the prevalence of pathogenic mutations in GJB2 gene ranged from 0% to 0.5%. The prevalence of pathogenic mutations in other known NSHI genes was <10% in Cameroonian probands. Environmental factors are the leading etiology of HI in Cameroon, and mutations in most important HI genes are infrequent in Cameroon. Whole genome sequencing therefore appears as the most effective way to identify variants associated with HI in Cameroon and sub-Saharan Africa in general.
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Affiliation(s)
- Edmond Wonkam Tingang
- Division of Human Genetics, Department of Pathology, University of Cape Town, Cape Town 7925, South Africa; (E.W.T.); (O.G.O.); (E.R.C.)
| | - Jean Jacques Noubiap
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide and Royal Adelaide Hospital, Adelaide 5000, Australia;
| | | | - Oluwafemi Gabriel Oluwole
- Division of Human Genetics, Department of Pathology, University of Cape Town, Cape Town 7925, South Africa; (E.W.T.); (O.G.O.); (E.R.C.)
| | - Séraphin Nguefack
- Department of Paediatrics, Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé 1364, Cameroon;
- Paediatrics unit, Gynaeco-Obstetric and Paediatric Hospital, Yaoundé 4362, Cameroon
| | - Emile R. Chimusa
- Division of Human Genetics, Department of Pathology, University of Cape Town, Cape Town 7925, South Africa; (E.W.T.); (O.G.O.); (E.R.C.)
| | - Ambroise Wonkam
- Division of Human Genetics, Department of Pathology, University of Cape Town, Cape Town 7925, South Africa; (E.W.T.); (O.G.O.); (E.R.C.)
- Department of Medicine, University of Cape Town, Cape Town 7925, South Africa
- Correspondence: ; Tel.: +27-21-4066-307
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Five Novel Mutations in LOXHD1 Gene Were Identified to Cause Autosomal Recessive Nonsyndromic Hearing Loss in Four Chinese Families. BIOMED RESEARCH INTERNATIONAL 2020; 2020:1685974. [PMID: 32149082 PMCID: PMC7049443 DOI: 10.1155/2020/1685974] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 01/17/2020] [Indexed: 01/31/2023]
Abstract
Hearing loss is one of the most common sensory disorders in newborns and is mostly caused by genetic factors. Autosomal recessive nonsyndromic hearing loss (ARNSHL) is usually characterized as a severe-to-profound congenital sensorineural hearing loss and later can cause various degrees of defect in the language and intelligent development of newborns. The mutations in LOXHD1 gene have been shown to cause DFNB77, a type of ARNSHL. To date, there are limited reports about the association between LOXHD1 gene and ARNSHL. In this study, we reported six patients from four Chinese families suffering from severe-to-profound nonsyndromic hearing loss. We performed targeted next generation sequencing in the six affected members and identified five novel pathogenic mutations in LOXHD1 including c.277G>A (p.D93N), c.611-2A>T, c.1255+3A>G, c.2329C>T (p.Q777 ∗ ), and c.5888delG (p.G1963Afs ∗ 136). These mutations were confirmed to be cosegregated with the hearing impairment in the families by Sanger sequencing and were inherited in an autosomal recessive pattern. All of the five mutations were absent in 200 control subjects. There were no symptoms of Fuchs corneal dystrophy in the probands and their blood-related relatives. We concluded that these five novel mutations could be involved in the underlying mechanism resulting in the hearing loss, and this discovery expands the genotypic spectrum of LOXHD1 mutations.
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M. Adadey S, Tingang Wonkam E, Twumasi Aboagye E, Quansah D, Asante-Poku A, Quaye O, K. Amedofu G, A. Awandare G, Wonkam A. Enhancing Genetic Medicine: Rapid and Cost-Effective Molecular Diagnosis for a GJB2 Founder Mutation for Hearing Impairment in Ghana. Genes (Basel) 2020; 11:genes11020132. [PMID: 32012697 PMCID: PMC7074138 DOI: 10.3390/genes11020132] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 01/21/2020] [Accepted: 01/22/2020] [Indexed: 12/17/2022] Open
Abstract
In Ghana, gap-junction protein β 2 (GJB2) variants account for about 25.9% of familial hearing impairment (HI) cases. The GJB2-p.Arg143Trp (NM_004004.6:c.427C>T/OMIM: 121011.0009/rs80338948) variant remains the most frequent variant associated with congenital HI in Ghana, but has not yet been investigated in clinical practice. We therefore sought to design a rapid and cost-effective test to detect this variant. We sampled 20 hearing-impaired and 10 normal hearing family members from 8 families segregating autosomal recessive non syndromic HI. In addition, a total of 111 unrelated isolated individuals with HI were selected, as well as 50 normal hearing control participants. A restriction fragment length polymorphism (RFLP) test was designed, using the restriction enzyme NciI optimized and validated with Sanger sequencing, for rapid genotyping of the common GJB2-p.Arg143Trp variant. All hearing-impaired participants from 7/8 families were homozygous positive for the GJB2-p.Arg143Trp mutation using the NciI-RFLP test, which was confirmed with Sanger sequencing. The investigation of 111 individuals with isolated non-syndromic HI that were previously Sanger sequenced found that the sensitivity of the GJB2-p.Arg143Trp NciI-RFLP testing was 100%. All the 50 control subjects with normal hearing were found to be negative for the variant. Although the test is extremely valuable, it is not 100% specific because it cannot differentiate between other mutations at the recognition site of the restriction enzyme. The GJB2-p.Arg143Trp NciI-RFLP-based diagnostic test had a high sensitivity for genotyping the most common GJB2 pathogenic and founder variant (p.Arg143Trp) within the Ghanaian populations. We recommend the adoption and implementation of this test for hearing impairment genetic clinical investigations to complement the newborn hearing screening program in Ghana. The present study is a practical case scenario of enhancing genetic medicine in Africa.
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Affiliation(s)
- Samuel M. Adadey
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra P. O. Box LG 54, Ghana; (S.M.A.); (E.T.A.); (D.Q.); (A.A.-P.); (O.Q.); (G.A.A.)
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa;
| | - Edmond Tingang Wonkam
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa;
| | - Elvis Twumasi Aboagye
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra P. O. Box LG 54, Ghana; (S.M.A.); (E.T.A.); (D.Q.); (A.A.-P.); (O.Q.); (G.A.A.)
| | - Darius Quansah
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra P. O. Box LG 54, Ghana; (S.M.A.); (E.T.A.); (D.Q.); (A.A.-P.); (O.Q.); (G.A.A.)
| | - Adwoa Asante-Poku
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra P. O. Box LG 54, Ghana; (S.M.A.); (E.T.A.); (D.Q.); (A.A.-P.); (O.Q.); (G.A.A.)
- Bacteriology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra P.O. Box LG 581, Ghana
| | - Osbourne Quaye
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra P. O. Box LG 54, Ghana; (S.M.A.); (E.T.A.); (D.Q.); (A.A.-P.); (O.Q.); (G.A.A.)
| | - Geoffrey K. Amedofu
- Department of Eye Ear Nose & Throat, School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi AK-039-5028, Ghana;
| | - Gordon A. Awandare
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra P. O. Box LG 54, Ghana; (S.M.A.); (E.T.A.); (D.Q.); (A.A.-P.); (O.Q.); (G.A.A.)
| | - Ambroise Wonkam
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa;
- Correspondence: ; Tel.: +27-21-4066-307
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Abstract
Ancestral and geographical issues underlie the need to develop Africa-specific guidelines for the return of genomic research results in Africa. In this Commentary, we outline the challenges that will inform policies and practices moving forward.
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Affiliation(s)
- Ambroise Wonkam
- Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
- Institute of Infectious Diseases and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
| | - Jantina de Vries
- Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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Zhang C, Hao S, Liu Y, Zhou B, Liu F, Zheng L, Ma P, Liu Q, Lin X, Yan Y, Zhang Q. A novel LOXHD1 variant in a Chinese couple with hearing loss. J Int Med Res 2019; 47:6082-6090. [PMID: 31709873 PMCID: PMC7045666 DOI: 10.1177/0300060519884197] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Objective To perform molecular diagnosis and genetic counseling in a young Chinese
couple with congenital hearing loss. Methods Variant screening analysis was performed by PCR and direct Sanger sequencing
or targeted next-generation sequencing of all known hearing loss genes.
Novel variants were evaluated by PolyPhen2 and PROVEAN software tools to
evaluate possible effects on protein function. Results We identified causative variants in the young couple: c.235delC
(rs80338943)/c.299-300delAT (rs111033204) compound heterozygous variants of
GJB2 in the husband and c.1828G>A (p.Glu610Lys,
rs535637788)/c.2825-2827delAGA compound heterozygous variants of
LOXHD1 in the wife. The LOXHD1
c.1828G>A variant has only previously been reported in a Mexican-American
individual in the 1000 Genomes Project database. Using PolyPhen2 and
PROVEAN, we speculated that the LOXHD1 variant c.1828G>A
is potentially pathogenic. Conclusion We carried out molecular diagnosis in a young couple with congenital hearing
loss, and identified different disease-causing genes in the two individuals.
The LOXHD1 variant c.1828G>A present in the wife had not
previously been reported in individuals with congenital hearing loss. We
determined this to be a potential pathogenic variant, and a novel variant
associated with hearing loss in a Chinese individual.
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Affiliation(s)
- Chuan Zhang
- Gansu Provincial Maternal and Child Health Care Hospital, Gansu Provincial Key Laboratory of Birth Defects Prevention and Control, Lanzhou, Gansu, China
| | - Shengju Hao
- Gansu Provincial Maternal and Child Health Care Hospital, Gansu Provincial Key Laboratory of Birth Defects Prevention and Control, Lanzhou, Gansu, China
| | - Yali Liu
- Gansu Provincial Maternal and Child Health Care Hospital, Gansu Provincial Key Laboratory of Birth Defects Prevention and Control, Lanzhou, Gansu, China
| | - Bingbo Zhou
- Gansu Provincial Maternal and Child Health Care Hospital, Gansu Provincial Key Laboratory of Birth Defects Prevention and Control, Lanzhou, Gansu, China
| | - Furong Liu
- Gansu Provincial Maternal and Child Health Care Hospital, Gansu Provincial Key Laboratory of Birth Defects Prevention and Control, Lanzhou, Gansu, China
| | - Lei Zheng
- Gansu Provincial Maternal and Child Health Care Hospital, Gansu Provincial Key Laboratory of Birth Defects Prevention and Control, Lanzhou, Gansu, China
| | - Panpan Ma
- Gansu Provincial Maternal and Child Health Care Hospital, Gansu Provincial Key Laboratory of Birth Defects Prevention and Control, Lanzhou, Gansu, China
| | - Qing Liu
- Gansu Provincial Maternal and Child Health Care Hospital, Gansu Provincial Key Laboratory of Birth Defects Prevention and Control, Lanzhou, Gansu, China
| | - Xiaojuan Lin
- Gansu Provincial Maternal and Child Health Care Hospital, Gansu Provincial Key Laboratory of Birth Defects Prevention and Control, Lanzhou, Gansu, China
| | - Yousheng Yan
- National Research Institute for Family Planning, Beijing, China
| | - Qinghua Zhang
- Gansu Provincial Maternal and Child Health Care Hospital, Gansu Provincial Key Laboratory of Birth Defects Prevention and Control, Lanzhou, Gansu, China
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GJB2 and GJB6 Mutations in Hereditary Recessive Non-Syndromic Hearing Impairment in Cameroon. Genes (Basel) 2019; 10:genes10110844. [PMID: 31731535 PMCID: PMC6895965 DOI: 10.3390/genes10110844] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 10/07/2019] [Accepted: 10/23/2019] [Indexed: 02/06/2023] Open
Abstract
This study aimed to investigate GJB2 (connexin 26) and GJB6 (connexin 30) mutations associated with familial non-syndromic childhood hearing impairment (HI) in Cameroon. We selected only families segregating HI, with at least two affected individuals and with strong evidence of non-environmental causes. DNA was extracted from peripheral blood, and the entire coding region of GJB2 was interrogated using Sanger sequencing. Multiplex PCR and Sanger sequencing were used to analyze the prevalence of the GJB6-D3S1830 deletion. A total of 93 patients, belonging to 41 families, were included in the analysis. Hearing impairment was sensorineural in 51 out of 54 (94.4%) patients. Pedigree analysis suggested autosomal recessive inheritance in 85.4% (35/41) of families. Hearing impairment was inherited in an autosomal dominant and mitochondrial mode in 12.2% (5/41) and 2.4% (1/41) of families, respectively. Most HI participants were non-syndromic (92.5%; 86/93). Four patients from two families presented with type 2 Waardenburg syndrome, and three cases of type 2 Usher syndrome were identified in one family. No GJB2 mutations were found in any of the 29 families with non-syndromic HI. Additionally, the GJB6-D3S1830 deletion was not identified in any of the HI patients. This study confirms that mutations in the GJB2 gene and the del(GJB6-D13S1830) mutation do not contribute to familial HI in Cameroon.
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Mutational Spectrum and Clinical Features of Patients with LOXHD1 Variants Identified in an 8074 Hearing Loss Patient Cohort. Genes (Basel) 2019; 10:genes10100735. [PMID: 31547530 PMCID: PMC6826470 DOI: 10.3390/genes10100735] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 08/28/2019] [Accepted: 09/19/2019] [Indexed: 12/16/2022] Open
Abstract
Variants of the LOXHD1 gene, which are expressed in hair cells of the cochlea and vestibule, have been reported to cause a progressive form of autosomal recessive non-syndromic hereditary hearing loss, DFNB77. In this study, genetic screening was conducted on 8074 Japanese hearing loss patients utilizing massively parallel DNA sequencing to identify individuals with LOXHD1 variants and to assess their phenotypes. A total of 28 affected individuals and 21 LOXHD1 variants were identified, among which 13 were novel variants. A recurrent variant c.4212 + 1G > A, only reported in Japanese patients, was detected in 18 individuals. Haplotype analysis implied that this variation occurred in a mutational hot spot, and that multiple ancestors of Japanese population had this variation. Patients with LOXHD1 variations mostly showed early onset hearing loss and presented different progression rates. We speculated that the varying severities and progression rates of hearing loss are the result of environmental and/or other genetic factors. No accompanying symptoms, including vestibular dysfunction, with hearing loss were detected in this study. Few studies have reported the clinical features of LOXHD1-gene associated hearing loss, and this study is by far the largest study focused on the evaluation of this gene.
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Adadey SM, Manyisa N, Mnika K, de Kock C, Nembaware V, Quaye O, Amedofu GK, Awandare GA, Wonkam A. GJB2 and GJB6 Mutations in Non-Syndromic Childhood Hearing Impairment in Ghana. Front Genet 2019; 10:841. [PMID: 31620164 PMCID: PMC6759689 DOI: 10.3389/fgene.2019.00841] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 08/13/2019] [Indexed: 01/16/2023] Open
Abstract
Our study aimed to investigate GJB2 (connexin 26) and GJB6 (connexin 30) mutations associated with non-syndromic childhood hearing impairment (HI) as well as the environmental causes of HI in Ghana. Medical reports of 1,104 students attending schools for the deaf were analyzed. Families segregating HI, as well as isolated cases of HI of putative genetic origin were recruited. DNA was extracted from peripheral blood followed by Sanger sequencing of the entire coding region of GJB2. Multiplex PCR and Sanger sequencing were used to analyze the prevalence of GJB6-D3S1830 deletion. Ninety-seven families segregating HI were identified, with 235 affected individuals; and a total of 166 isolated cases of putative genetic causes, were sampled from 11 schools for the deaf in Ghana. The environmental factors, particularly meningitis, remain a major cause of HI impairment in Ghana. The male/female ratio was 1.49. Only 59.6% of the patients had their first comprehensive HI test between 6 to 11 years of age. Nearly all the participants had sensorineural HI (99.5%; n = 639). The majority had pre-lingual HI (68.3%, n = 754), of which 92.8% were congenital. Pedigree analysis suggested autosomal recessive inheritance in 96.9% of the familial cases. GJB2-R143W mutation, previously reported as founder a mutation in Ghana accounted for 25.9% (21/81) in the homozygous state in familial cases, and in 7.9% (11/140) of non-familial non-syndromic congenital HI cases, of putative genetic origin. In a control population without HI, we found a prevalent of GJB2-R143W carriers of 1.4% (2/145), in the heterozygous state. No GJB6-D3S1830 deletion was identified in any of the HI patients. GJB2-R143W mutation accounted for over a quarter of familial non-syndromic HI in Ghana and should be investigated in clinical practice. The large connexin 30 gene deletion (GJB6-D3S1830 deletion) does not account for of congenital non-syndromic HI in Ghana. There is a need to employ next generation sequencing approaches and functional genomics studies to identify the other genes involved in most families and isolated cases of HI in Ghana.
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Affiliation(s)
- Samuel M. Adadey
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
| | - Noluthando Manyisa
- Division of Human Genetics, Faculty of Health Sciences—University of Cape Town, Cape Town , South Africa
| | - Khuthala Mnika
- Division of Human Genetics, Faculty of Health Sciences—University of Cape Town, Cape Town , South Africa
| | - Carmen de Kock
- Division of Human Genetics, Faculty of Health Sciences—University of Cape Town, Cape Town , South Africa
| | - Victoria Nembaware
- Division of Human Genetics, Faculty of Health Sciences—University of Cape Town, Cape Town , South Africa
| | - Osbourne Quaye
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
| | - Geoffrey K. Amedofu
- Department of Eye, Ear, Nose and Throat, School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Gordon A. Awandare
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
| | - Ambroise Wonkam
- Division of Human Genetics, Faculty of Health Sciences—University of Cape Town, Cape Town , South Africa
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Gardiner SA, Laing N, Mall S, Wonkam A. Perceptions of parents of children with hearing loss of genetic origin in South Africa. J Community Genet 2019; 10:325-333. [PMID: 30465126 PMCID: PMC6591331 DOI: 10.1007/s12687-018-0396-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 11/06/2018] [Indexed: 01/15/2023] Open
Abstract
More than 80% of people with hearing loss (HL) live in low- and middle-income countries. Up to 90% of deaf children are born to hearing parents, leading to novel parenting, communication, educational, and psychosocial experiences. Half of congenital pre-lingual HL is genetic, with a relatively high recurrence risk that may lead to specific challenges for parents of affected children. Currently, little is known of genes implicated and causative mutations for most populations who have HL in Sub-Saharan Africa, as well as genetic counseling services needs for this population. Therefore, this study aimed to explore parents' perceptions and understanding of the genetic etiology of their child's HL, in order to inform policies and services. In-depth qualitative interviews were conducted with 11 parents of children who have non-syndromic HL of putative genetic origin. Data were analyzed through the framework approach. Three salient themes emerged, namely comprehension and understanding of the cause, in which most parents were unable to identify the potential hereditary cause of their child's HL; responsibility and blame; and their perception of genetic counseling and testing. Most of the participants had positive attitudes towards genetic testing, describing that it may provide answers and that the information gained would be helpful for the future. The data could assist in understanding the challenges faced by parents, in the absence of genetic testing, emphasizing the need for accurate genetic testing to support counseling services to parents of children with HL in an African Setting.
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Affiliation(s)
- Sinead Amber Gardiner
- Division of Human Genetics, Falmouth Building, Faculty of Health Sciences, Department of Pathology, University of Cape Town, Observatory, Cape Town, 7925, South Africa
| | - Nakita Laing
- Division of Human Genetics, Groote Schuur Hospital/Red Cross War Memorial Children's Hospital, Cape Town, South Africa
| | - Sumaya Mall
- Department of Psychiatry and Mental Health, University of Cape Town, Faculty of Health Sciences, Cape Town, South Africa
- Division of Epidemiology and Biostatistics, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Ambroise Wonkam
- Division of Human Genetics, Falmouth Building, Faculty of Health Sciences, Department of Pathology, University of Cape Town, Observatory, Cape Town, 7925, South Africa.
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Shen N, Wang T, Li D, Liu A, Lu Y. Whole-exome sequencing identifies a novel missense variant within LOXHD1 causing rare hearing loss in a Chinese family. BMC MEDICAL GENETICS 2019; 20:30. [PMID: 30760222 PMCID: PMC6373029 DOI: 10.1186/s12881-019-0758-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 01/22/2019] [Indexed: 11/10/2022]
Abstract
Background Deafness, autosomal recessive 77 (DFNB77) is a rare non-syndromic hearing loss (NSHL) worldwide, which is caused by deleterious variants within lipoxygenase homology domains 1 (LOXHD1). Here we identified that a novel missense variant of LOXHD1 was associated with NSHL in a Chinese family under consanguineous marriage. Case presentation A 28-year-old woman suffered a bilateral profound NSHL. Impedance audiometry, temporal bone computerized tomography (TBCT) scans and magnetic resonance imaging-inner ear hydrography (MRI-IEH) did not find any obvious abnormality of middle or inner ear. Routine genetic detection did not find pathogenic variants in common HL-associated genes. Therefore, we performed a whole-exome sequencing (WES) in this family. By trio-WES, co-segregation validation and bioinformatics analysis, we revealed that a novel homozygous variant in this patient, LOXHD1: c.5948C > T (p.S1983F), might be the pathogenic factor. Her parents (heterozygotes) and brother (wild-type) were asymptomatic. Conclusions We successfully identified a novel variant of LOXHD1 associated with a rare NSHL from a Chinese family. Our finds highlight the effectiveness of trio-WES for molecular diagnosis of rare NHSL, and expand the genotypic spectrum of DFNB77. Electronic supplementary material The online version of this article (10.1186/s12881-019-0758-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Na Shen
- Department of Laboratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Ting Wang
- Department of Laboratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Delei Li
- Department of Laboratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Aiguo Liu
- Department of Otorhinolaryngology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Yanjun Lu
- Department of Laboratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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Gibriel AA, Abou-Elew MH, Masmoudi S. Analysis of p.Gly12Valfs*2, p.Trp24* and p.Trp77Arg mutations in GJB2 and p.Arg81Gln variant in LRTOMT among non syndromic hearing loss Egyptian patients: implications for genetic diagnosis. Mol Biol Rep 2019; 46:2139-2145. [PMID: 30730013 DOI: 10.1007/s11033-019-04667-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 01/30/2019] [Indexed: 11/28/2022]
Abstract
Hearing loss (HL) is a global sensory disorder that affects children and deprives them from their rights to enjoy standard social and educational levels. Although hundreds of genetic mutations across several genes have been linked to HL, very limited studies are available on Egyptian population which has high rate of consanguinity and HL. The frequency of the p.Gly12Valfs*2, p.Trp24* and p.Trp77Arg mutations in GJB2 along with the p.Arg81Gln variant in LRTOMT gene was investigated in Egyptian patients. 103 non-syndromic HL (NSHL) Egyptian patients and 100 control subjects were recruited in this study. PCR-RFLP and Direct sequencing were performed to screen and confirm presence/absence of those mutations in Egyptian population. The p.Gly12Valfs*2 mutation was found in eight patients (7.8%) (six homozygous and two heterozygous) with an allele frequency of 6.8%. The p.Trp24* and p.Trp77Arg were absent in both HL patients and controls. Another one patient had the heterozygous variant for p.Arg81Gln in LRTOMT gene. This study reports, for the first time, the presence of a heterozygous change for the p.Arg81Gln in LRTOMT gene in one Egyptian patient. The p.Gly12Valfs*2 mutation, but not the p.Trp24* nor the p.Trp77Arg, in GJB2 is the most frequent variant among Egyptian patients and would therefore be recommended for genetic counseling and diagnosis.
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Affiliation(s)
- Abdullah A Gibriel
- Biochemistry and Molecular Biology Department, Faculty of Pharmacy, The British University in Egypt (BUE), P.O. Box 259, 11728, Cairo, Egypt.
| | - Maha H Abou-Elew
- Otorhinolaryngology Department, Audio-Vestibular Unit, Faculty of Medicine, Kasr Al-Aini El-Manial University Hospital, Cairo University, Giza, Egypt
| | - Saber Masmoudi
- Laboboratoire Procédés de Criblage Moléculaire et Cellulaire, Centre de Biotechnologie de Sfax, Université de Sfax, Sfax, Tunisia
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Xu T, Zhu W, Wang P. The p.P240L variant of CDH23 and the risk of nonsyndromic hearing loss: a meta-analysis. Eur Arch Otorhinolaryngol 2018; 276:11-16. [DOI: 10.1007/s00405-018-5160-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Accepted: 10/04/2018] [Indexed: 01/11/2023]
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Krause A, Seymour H, Ramsay M. Common and Founder Mutations for Monogenic Traits in Sub-Saharan African Populations. Annu Rev Genomics Hum Genet 2018; 19:149-175. [DOI: 10.1146/annurev-genom-083117-021256] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This review highlights molecular genetic studies of monogenic traits where common pathogenic mutations occur in black families from sub-Saharan Africa. Examples of founder mutations have been identified for oculocutaneous albinism, cystic fibrosis, Fanconi anemia, and Gaucher disease. Although there are few studies from Africa, some of the mutations traverse populations across the continent, and they are almost all different from the common mutations observed in non-African populations. Myotonic dystrophy is curiously absent among Africans, and nonsyndromic deafness does not arise from mutations in GJB2 and GJB7. Locus heterogeneity is present for Huntington disease, with two common triplet expansion loci in Africa, HTT and JPH3. These findings have important clinical consequences for diagnosis, treatment, and genetic counseling in affected families. We currently have just a glimpse of the molecular etiology of monogenic diseases in sub-Saharan Africa, a proverbial “ears of the hippo” situation.
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Affiliation(s)
- Amanda Krause
- Division of Human Genetics, National Health Laboratory Service, and Division of Human Genetics, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Heather Seymour
- Division of Human Genetics, National Health Laboratory Service, and Division of Human Genetics, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Michèle Ramsay
- Division of Human Genetics, National Health Laboratory Service, and Division of Human Genetics, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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Mitropoulos K, Cooper DN, Mitropoulou C, Agathos S, Reichardt JKV, Al-Maskari F, Chantratita W, Wonkam A, Dandara C, Katsila T, Lopez-Correa C, Ali BR, Patrinos GP. Genomic Medicine Without Borders: Which Strategies Should Developing Countries Employ to Invest in Precision Medicine? A New "Fast-Second Winner" Strategy. OMICS : A JOURNAL OF INTEGRATIVE BIOLOGY 2018; 21:647-657. [PMID: 29140767 DOI: 10.1089/omi.2017.0141] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Genomic medicine has greatly matured in terms of its technical capabilities, but the diffusion of genomic innovations worldwide faces significant barriers beyond mere access to technology. New global development strategies are sorely needed for biotechnologies such as genomics and their applications toward precision medicine without borders. Moreover, diffusion of genomic medicine globally cannot adhere to a "one-size-fits-all-countries" development strategy, in the same way that drug treatments should be customized. This begs a timely, difficult but crucial question: How should developing countries, and the resource-limited regions of developed countries, invest in genomic medicine? Although a full-scale investment in infrastructure from discovery to the translational implementation of genomic science is ideal, this may not always be feasible in all countries at all times. A simple "transplantation of genomics" from developed to developing countries is unlikely to be feasible. Nor should developing countries be seen as simple recipients and beneficiaries of genomic medicine developed elsewhere because important advances in genomic medicine have materialized in developing countries as well. There are several noteworthy examples of genomic medicine success stories involving resource-limited settings that are contextualized and described in this global genomic medicine innovation analysis. In addition, we outline here a new long-term development strategy for global genomic medicine in a way that recognizes the individual country's pressing public health priorities and disease burdens. We term this approach the "Fast-Second Winner" model of innovation that supports innovation commencing not only "upstream" of discovery science but also "mid-stream," building on emerging highly promising biomarker and diagnostic candidates from the global science discovery pipeline, based on the unique needs of each country. A mid-stream entry into innovation can enhance collective learning from other innovators' mistakes upstream in discovery science and boost the probability of success for translation and implementation when resources are limited. This à la carte model of global innovation and development strategy offers multiple entry points into the global genomics innovation ecosystem for developing countries, whether or not extensive and expensive discovery infrastructures are already in place. Ultimately, broadening our thinking beyond the linear model of innovation will help us to enable the vision and practice of genomics without borders in both developed and resource-limited settings.
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Affiliation(s)
| | - David N Cooper
- 2 Institute of Medical Genetics, School of Medicine, Cardiff University , Cardiff, United Kingdom
| | | | - Spiros Agathos
- 4 Yachay Tech University , San Miguel de Urcuquí, Ecuador
| | | | - Fatima Al-Maskari
- 5 Department of Pathology, College of Medicine and Health Sciences, United Arab Emirates University , Al-Ain, United Arab Emirates .,6 Zayed Bin Sultan Center for Health Sciences, United Arab Emirates University , Al-Ain, United Arab Emirates
| | - Wasun Chantratita
- 7 Department of Pathology, Medical Genomic Center, Ramathibodi Hospital, Faculty of Medicine, Mahidol University , Bangkok, Thailand
| | - Ambroise Wonkam
- 8 Division of Human Genetics, Department of Medicine and Institute of Infectious Disease and Molecular Medicine, University of Cape Town , Cape Town, South Africa
| | - Collet Dandara
- 8 Division of Human Genetics, Department of Medicine and Institute of Infectious Disease and Molecular Medicine, University of Cape Town , Cape Town, South Africa
| | - Theodora Katsila
- 9 Department of Pharmacy, School of Health Sciences, University of Patras , Patras, Greece
| | | | - Bassam R Ali
- 5 Department of Pathology, College of Medicine and Health Sciences, United Arab Emirates University , Al-Ain, United Arab Emirates .,6 Zayed Bin Sultan Center for Health Sciences, United Arab Emirates University , Al-Ain, United Arab Emirates
| | - George P Patrinos
- 5 Department of Pathology, College of Medicine and Health Sciences, United Arab Emirates University , Al-Ain, United Arab Emirates .,6 Zayed Bin Sultan Center for Health Sciences, United Arab Emirates University , Al-Ain, United Arab Emirates .,9 Department of Pharmacy, School of Health Sciences, University of Patras , Patras, Greece
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30
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Wesdorp M, Schreur V, Beynon AJ, Oostrik J, van de Kamp JM, Elting MW, van den Boogaard MJH, Feenstra I, Admiraal RJC, Kunst HPM, Hoyng CB, Kremer H, Yntema HG, Pennings RJE, Schraders M. Further audiovestibular characterization of DFNB77, caused by deleterious variants in LOXHD1, and investigation into the involvement of Fuchs corneal dystrophy. Clin Genet 2018; 94:221-231. [PMID: 29676012 DOI: 10.1111/cge.13368] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 04/08/2018] [Accepted: 04/16/2018] [Indexed: 12/15/2022]
Abstract
This study focuses on further characterization of the audiovestibular phenotype and on genotype-phenotype correlations of DFNB77, an autosomal recessive type of hearing impairment (HI). DFNB77 is associated with disease-causing variants in LOXHD1, and is genetically and phenotypically highly heterogeneous. Heterozygous deleterious missense variants in LOXHD1 have been associated with late-onset Fuchs corneal dystrophy (FCD). However, up to now screening for FCD of heterozygous carriers in DFNB77 families has not been reported. This study describes the genotype and audiovestibular phenotype of 9 families with DFNB77. In addition, carriers within the families were screened for FCD. Fifteen pathogenic missense and truncating variants were identified, of which 12 were novel. The hearing phenotype showed high inter- and intrafamilial variation in severity and progression. There was no evidence for involvement of the vestibular system. None of the carriers showed (pre-clinical) symptoms of FCD. Our findings expand the genotypic and phenotypic spectrum of DFNB77, but a clear correlation between the type or location of the variant and the severity or progression of HI could not be established. We hypothesize that environmental factors or genetic modifiers are responsible for phenotypic differences. No association was found between heterozygous LOXHD1 variants and the occurrence of FCD in carriers.
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Affiliation(s)
- M Wesdorp
- Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, the Netherlands.,The Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands.,Department of Cognition and Behaviour, Donders Institute for Brain, Radboud University Medical Center, Nijmegen, the Netherlands
| | - V Schreur
- Department of Cognition and Behaviour, Donders Institute for Brain, Radboud University Medical Center, Nijmegen, the Netherlands.,Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - A J Beynon
- Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, the Netherlands.,Department of Cognition and Behaviour, Donders Institute for Brain, Radboud University Medical Center, Nijmegen, the Netherlands
| | - J Oostrik
- Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, the Netherlands.,Department of Cognition and Behaviour, Donders Institute for Brain, Radboud University Medical Center, Nijmegen, the Netherlands
| | - J M van de Kamp
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, the Netherlands
| | - M W Elting
- Department of Clinical Genetics, VU University Medical Center, Amsterdam, the Netherlands
| | | | - I Feenstra
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - R J C Admiraal
- Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, the Netherlands
| | - H P M Kunst
- Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, the Netherlands.,Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - C B Hoyng
- Department of Cognition and Behaviour, Donders Institute for Brain, Radboud University Medical Center, Nijmegen, the Netherlands.,Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - H Kremer
- Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, the Netherlands.,Department of Cognition and Behaviour, Donders Institute for Brain, Radboud University Medical Center, Nijmegen, the Netherlands.,Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - H G Yntema
- Department of Cognition and Behaviour, Donders Institute for Brain, Radboud University Medical Center, Nijmegen, the Netherlands.,Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - R J E Pennings
- Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, the Netherlands.,Department of Cognition and Behaviour, Donders Institute for Brain, Radboud University Medical Center, Nijmegen, the Netherlands
| | - M Schraders
- Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, the Netherlands.,Department of Cognition and Behaviour, Donders Institute for Brain, Radboud University Medical Center, Nijmegen, the Netherlands
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Lebeko K, Manyisa N, Chimusa ER, Mulder N, Dandara C, Wonkam A. A Genomic and Protein-Protein Interaction Analyses of Nonsyndromic Hearing Impairment in Cameroon Using Targeted Genomic Enrichment and Massively Parallel Sequencing. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2017; 21:90-99. [PMID: 28075205 DOI: 10.1089/omi.2016.0171] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Hearing impairment (HI) is one of the leading causes of disability in the world, impacting the social, economic, and psychological well-being of the affected individual. This is particularly true in sub-Saharan Africa, which carries one of the highest burdens of this condition. Despite this, there are limited data on the most prevalent genes or mutations that cause HI among sub-Saharan Africans. Next-generation technologies, such as targeted genomic enrichment and massively parallel sequencing, offer new promise in this context. This study reports, for the first time to the best of our knowledge, on the prevalence of novel mutations identified through a platform of 116 HI genes (OtoSCOPE®), among 82 African probands with HI. Only variants OTOF NM_194248.2:c.766-2A>G and MYO7A NM_000260.3:c.1996C>T, p.Arg666Stop were found in 3 (3.7%) and 5 (6.1%) patients, respectively. In addition and uniquely, the analysis of protein-protein interactions (PPI), through interrogation of gene subnetworks, using a custom script and two databases (Enrichr and PANTHER), and an algorithm in the igraph package of R, identified the enrichment of sensory perception and mechanical stimulus biological processes, and the most significant molecular functions of these variants pertained to binding or structural activity. Furthermore, 10 genes (MYO7A, MYO6, KCTD3, NUMA1, MYH9, KCNQ1, UBC, DIAPH1, PSMC2, and RDX) were identified as significant hubs within the subnetworks. Results reveal that the novel variants identified among familial cases of HI in Cameroon are not common, and PPI analysis has highlighted the role of 10 genes, potentially important in understanding HI genomics among Africans.
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Affiliation(s)
- Kamogelo Lebeko
- 1 Division of Human Genetics, Department of Pathology, Faculty of Health Sciences - University of Cape Town , Cap Town, South Africa
| | - Noluthando Manyisa
- 1 Division of Human Genetics, Department of Pathology, Faculty of Health Sciences - University of Cape Town , Cap Town, South Africa
| | - Emile R Chimusa
- 1 Division of Human Genetics, Department of Pathology, Faculty of Health Sciences - University of Cape Town , Cap Town, South Africa
| | - Nicola Mulder
- 2 Division of Computational Biology, Faculty of Health Sciences - University of Cape Town , Cap Town, South Africa
| | - Collet Dandara
- 1 Division of Human Genetics, Department of Pathology, Faculty of Health Sciences - University of Cape Town , Cap Town, South Africa
| | - Ambroise Wonkam
- 1 Division of Human Genetics, Department of Pathology, Faculty of Health Sciences - University of Cape Town , Cap Town, South Africa .,3 Department of Medicine, Faculty of Health Sciences - University of Cape Town , Cap Town, South Africa
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Abstract
PURPOSE OF REVIEW In the age of targeted genomic enrichment and massively parallel sequencing, there is no more efficient genetic testing method for the diagnosis of hereditary hearing loss. More clinical tests are on the market, which can make choosing good tests difficult. RECENT FINDINGS More and larger comprehensive genetic studies in patients with hearing loss have been published recently. They remind us of the importance of looking for both single nucleotide variation and copy number variation in all genes implicated in nonsyndromic hearing loss. They also inform us of how a patient's history and phenotype provide essential information in the interpretation of genetic data. SUMMARY Choosing the most comprehensive genetic test improves the chances of a genetic diagnosis and thereby impacts clinical care.
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