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Van der Merwe NC, Combrink HM, Ntaita KS, Oosthuizen J. Prevalence of Clinically Relevant Germline BRCA Variants in a Large Unselected South African Breast and Ovarian Cancer Cohort: A Public Sector Experience. Front Genet 2022; 13:834265. [PMID: 35464868 PMCID: PMC9024354 DOI: 10.3389/fgene.2022.834265] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 02/23/2022] [Indexed: 01/14/2023] Open
Abstract
Breast cancer is a multifaceted disease that currently represents a leading cause of death in women worldwide. Over the past two decades (1998–2020), the National Health Laboratory Service’s Human Genetics Laboratory in central South Africa screened more than 2,974 breast and/or ovarian cancer patients for abnormalities characteristic of the widely known familial breast cancer genes, Breast Cancer gene 1 (BRCA1) and Breast Cancer gene 2 (BRCA2). Patients were stratified according to the presence of family history, age at onset, stage of the disease, ethnicity and mutation status relative to BRCA1/2. Collectively, 481 actionable (likely-to pathogenic) variants were detected in this cohort among the different ethnic/racial groups. A combination of old (pre-2014) and new (post-2014) laboratory techniques was used to identify these variants. Additionally, targeted genotyping was performed as translational research revealed the first three recurrent South African pathogenic variants, namely BRCA1 c.1374del (legacy name 1493delC), BRCA1 c.2641G>T (legacy name E881X) and BRCA2 c.7934del (legacy name 8162delG). This initial flagship study resulted in a cost-effective diagnostic test that enabled screening of a particular ethnic group for these variants. Since then, various non-Afrikaner frequent variants were identified that were proven to represent recurrent variants. These include BRCA2 c.5771_5774del (legacy name 5999del4) and BRCA2 c.582G>A, both Black African founder mutations. By performing innovative translational research, medical science in South Africa can adopt first-world technologies into its healthcare context as a developing country. Over the past two decades, the progress made in the public sector enabled a pivotal shift away from population-directed genetic testing to the screening of potentially all breast and ovarian cancer patients, irrespective of ethnicity, family history or immunohistochemical status. The modifications over the years complied with international standards and guidelines aimed at universal healthcare for all. This article shares all the cohort stratifications and the likely-to pathogenic variants detected.
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Affiliation(s)
- Nerina C. Van der Merwe
- Division of Human Genetics, National Health Laboratory Service, Bloemfontein, South Africa
- Division of Human Genetics, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa
- *Correspondence: Nerina C. Van der Merwe,
| | - Herkulaas MvE Combrink
- Economic and Management Sciences, University of the Free State, Bloemfontein, South Africa
- Interdisciplinary Centre for Digital Futures, University of the Free State, Bloemfontein, South Africa
| | - Kholiwe S. Ntaita
- Division of Human Genetics, National Health Laboratory Service, Bloemfontein, South Africa
- Division of Human Genetics, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa
| | - Jaco Oosthuizen
- Division of Human Genetics, National Health Laboratory Service, Bloemfontein, South Africa
- Division of Human Genetics, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa
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Kasu M, Cloete K, Pitere R, Tsiana K, D’Amato M. The Genetic Landscape of South African males: A Y-STR Perspective. Forensic Sci Int Genet 2022; 58:102677. [DOI: 10.1016/j.fsigen.2022.102677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 01/21/2022] [Accepted: 02/04/2022] [Indexed: 11/04/2022]
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Combrink HM, Oosthuizen J, Visser B, Chabilal N, Buccimazza I, Foulkes WD, van der Merwe NC. Mutations in BRCA-related breast and ovarian cancer in the South African Indian population: A descriptive study. Cancer Genet 2021; 258-259:1-6. [PMID: 34218100 DOI: 10.1016/j.cancergen.2021.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 02/07/2021] [Accepted: 06/06/2021] [Indexed: 10/21/2022]
Abstract
Knowledge of the genetic landscape of a specific population group is vital for population-specific diagnosis and treatment of familial breast cancer. Although BRCA-related diagnostic testing has long been implemented in South Africa, the genotyping approach previously failed for the SA Indian population as it was based on other SA population groups. Because this population is uniquely admixed, the lack of population-specific data resulted in the implementation of comprehensive mutation screens for BRCA1/2. A total of 223 female patients were screened for clinically actionable variants. High-resolution melting analysis (HRMA) was used to screen 88 patients for DNA alterations in the coding and splice site boundaries of BRCA1 exons 2-9, BRCA1 exons 11-23, BRCA2 exons 2-9 and BRCA2 exons 12-27. The protein truncation test (PTT) was used to screen the three larger exons (BRCA1 exon 10 and BRCA2 exons 10 and 11) for protein termination changes. Multiplex ligation-dependent probe amplification (MLPA) was used to determine the presence of larger indels and possible copy number differences. Next Generation Sequencing (NGS) was performed on the remaining 135 samples. All potential variants were confirmed by performing Sanger DNA sequencing. The search revealed 28 different pathogenic heterozygotic variants, together with nine variants of unknown significance (VUS). The results suggested that the SA Indian population represents a different genetic admixture compared to that of mainland India, as only five pathogenic variants corresponded to those reported for mainland India. Familial breast cancer testing for SA Indian patients should therefore be performed as comprehensively as possible as the pathogenic variants seem to be family- rather than population-specific. Furthermore, predictive testing of family members will contribute to relieve the financial burden on the country's healthcare system, as increased surveillance and appropriate management could prevent disease.
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Affiliation(s)
- Herkulaas Mve Combrink
- Division of Human Genetics, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa; Division of Human Genetics, National Health Laboratory Services, Universitas Hospital, Bloemfontein, South Africa.
| | - Jaco Oosthuizen
- Division of Human Genetics, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa; Division of Human Genetics, National Health Laboratory Services, Universitas Hospital, Bloemfontein, South Africa
| | - Botma Visser
- Department of Plant Sciences, Faculty of Natural and Agricultural Sciences, University of the Free State, Bloemfontein, South Africa
| | - Namitha Chabilal
- Genetics Unit, Inkosi Albert Luthuli General Hospital, Durban, South Africa
| | - Ines Buccimazza
- Department of Surgery, Faculty of Medicine, Inkosi Albert Luthuli General Hospital, Durban, South Africa
| | - William D Foulkes
- Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, Montréal, QC, Canada; Research Institute of the McGill University Health Centre, Montréal, QC, Canada; Program in Cancer Genetics, Departments of Oncology and Human Genetics, McGill University, Montréal, QC, Canada
| | - Nerina C van der Merwe
- Division of Human Genetics, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa; Division of Human Genetics, National Health Laboratory Services, Universitas Hospital, Bloemfontein, South Africa
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