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Yildiz S, Musarurwa TN, Algar U, Chambuso R, Rebello G, Goldberg PA, Ramesar R. Genetic insights: High germline variant rate in an indigenous African cohort with early-onset colorectal cancer. Front Oncol 2023; 13:1253867. [PMID: 37965459 PMCID: PMC10642181 DOI: 10.3389/fonc.2023.1253867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 09/25/2023] [Indexed: 11/16/2023] Open
Abstract
Introduction The increase in incidence of colorectal cancer in young patients of African ancestry coupled with increased aggressiveness has warranted investigation of the heritable nature of these cancers. Only a limited number of published reports of hereditary colorectal cancer in indigenous African populations have been reported and no systematic screening of these groups has been performed previously. We aimed to investigate causative germline variants and to establish the incidence of pathogenic/likely pathogenic germline variants in the known colorectal cancer genes in indigenous African colorectal cancer patients using a next-generation sequencing (NGS) multigene panel. Materials and methods Patients were selected from two hospitals in Cape Town and Johannesburg, South Africa. Patients with unresolved molecular diagnosis with an age of onset below or at 60 years were selected. Germline DNA samples were analyzed using a 14-gene NGS panel on the Ion Torrent platform. Variant calling and annotation were performed, and variants were classified according to the American College of Medical Genetics and Genomics guidelines. Observed variants were verified by Sanger sequencing and/or long-range PCR. Results Out of 107 patients, 25 (23.4%) presented with a pathogenic/likely pathogenic germline variant (PGV). Fourteen PGVs in at least one mismatch repair (MMR) gene were identified and verified in 12 patients (11.2%). Of these MMR gene variants, five were novel. The remaining 10 PGVs were in the APC, BMPR1A, MUTYH, POLD1, and TP53 genes. Conclusion The high incidence of PGVs associated with early-onset colorectal cancer in indigenous African patients has important implications for hereditary colorectal cancer risk management. These findings pave the way for personalized genetic screening programs and cascade testing in South Africa. The next step would involve further screening of the unresolved cases using tools to detect copy number variation, methylation, and whole exome sequencing.
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Affiliation(s)
- Safiye Yildiz
- UCT/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, University of Cape Town and Affiliated Hospitals, Cape Town, South Africa
| | - Takudzwa N. Musarurwa
- UCT/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, University of Cape Town and Affiliated Hospitals, Cape Town, South Africa
| | - Ursula Algar
- The Colorectal Unit of the Department of Surgery, Groote Schuur Hospital and the University of Cape Town, Cape Town, South Africa
| | - Ramadhani Chambuso
- UCT/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, University of Cape Town and Affiliated Hospitals, Cape Town, South Africa
| | - George Rebello
- UCT/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, University of Cape Town and Affiliated Hospitals, Cape Town, South Africa
| | - Paul A. Goldberg
- The Colorectal Unit of the Department of Surgery, Groote Schuur Hospital and the University of Cape Town, Cape Town, South Africa
| | - Raj Ramesar
- UCT/MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, University of Cape Town and Affiliated Hospitals, Cape Town, South Africa
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Bouras A, Naibo P, Legrand C, Marc’hadour FL, Ruano E, Grand-Masson C, Lefol C, Wang Q. A PMS2 non-canonical splicing site variant leads to aberrant splicing in a patient suspected for lynch syndrome. Fam Cancer 2022:10.1007/s10689-022-00323-y. [DOI: 10.1007/s10689-022-00323-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 11/25/2022] [Indexed: 11/30/2022]
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Djursby M, Madsen MB, Frederiksen JH, Berchtold LA, Therkildsen C, Willemoe GL, Hasselby JP, Wikman F, Okkels H, Skytte AB, Nilbert M, Wadt K, Gerdes AM, van Overeem Hansen T. New Pathogenic Germline Variants in Very Early Onset and Familial Colorectal Cancer Patients. Front Genet 2020; 11:566266. [PMID: 33193653 PMCID: PMC7541943 DOI: 10.3389/fgene.2020.566266] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/24/2020] [Indexed: 12/30/2022] Open
Abstract
A genetic diagnosis facilitates personalized cancer treatment and clinical care of relatives at risk, however, although 25% of colorectal cancer cases are familial, around 95% of the families are genetically unresolved. In this study, we performed gene panel analysis on germline DNA of 32 established or candidate colorectal cancer predisposing genes in 149 individuals from either families with an accumulation of colorectal cancers or families with only one sporadic case of very early onset colorectal cancer (≤40 years at diagnosis). We identified pathogenic or likely pathogenic genetic variants in 10.1% of the participants in genes such as APC, POLE, MSH2 or PMS2. The MSH2 variant, c.2168C>T, p.(Ser723Phe) was previously described as a variant of unknown significance, but we have now reclassified it to be likely pathogenic. The POLE variant, c.1089C>A, p.(Asn363Lys) was identified in a patient with three metachronous colorectal cancers from age 28 and turned out to be de novo. One pathogenic PMS2 variant was novel. We also identified a number of highly interesting variants of unknown significance in APC, BUB1, TP53 and RPS20. The RPS20 variant is novel and was found in a large Amsterdam I positive family with a multi tumor phenotype including 12 cases of CRC from as early as age 24. This variant was found to segregate with cancer in the family and multiple in silico tools predict it to be pathogenic. Our data further support the shift from phenotypic-based cancer panels to large panels including all established genes involved in hereditary cancer syndromes or (targeted) whole genome sequencing. Additionally, identification of a likely disease-predisposing variant in RPS20 expands the phenotypic spectrum of RPS20-related cancers and emphasize that this gene is relevant to include in colorectal cancer gene panels.
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Affiliation(s)
- Malene Djursby
- Department of Clinical Genetics, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Majbritt B Madsen
- Center for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Jane H Frederiksen
- Department of Clinical Genetics, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Lukas A Berchtold
- Center for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Christina Therkildsen
- The Danish HNPCC Register, Clinical Research Centre, Copenhagen University Hospital, Hvidovre, Denmark
| | - Gro L Willemoe
- Department of Pathology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Jane P Hasselby
- Department of Pathology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Friedrik Wikman
- Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Henrik Okkels
- Section of Molecular Diagnostics, Department of Clinical Chemistry, Aalborg University Hospital, Aalborg, Denmark
| | - Anne-Bine Skytte
- Department of Clinical Genetics, Aarhus University Hospital, Aarhus, Denmark
| | - Mef Nilbert
- The Danish HNPCC Register, Clinical Research Centre, Copenhagen University Hospital, Hvidovre, Denmark
| | - Karin Wadt
- Department of Clinical Genetics, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Anne-Marie Gerdes
- Department of Clinical Genetics, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Thomas van Overeem Hansen
- Department of Clinical Genetics, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
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