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Chambuso R, Robertson B, Ramesar R. A Scoring Model and Protocol to Adapt Universal Screening for Lynch Syndrome to Identify Germline Pathogenic Variants by Next Generation Sequencing from Colorectal Cancer Patients and Cascade Screening. Cancers (Basel) 2022; 14:cancers14122901. [PMID: 35740566 PMCID: PMC9220991 DOI: 10.3390/cancers14122901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/14/2022] [Accepted: 04/22/2022] [Indexed: 12/03/2022] Open
Abstract
Simple Summary Lynch syndrome (LS) is an autosomal-dominantly inherited form of cancer predisposition dominated by colorectal cancer (CRC). LS is caused by germline pathogenic variants (PV) occurring in known mismatch repair genes. For effective cascade screening, it is critical to identify PV for LS predisposition. When limited resources are available, next generation sequencing (NGS) of an entire cohort of colorectal cancer (CRC) patients, even those under 50 or 60 years of age, places a huge burden on the system. Here, we present an innovative LS ascertainment and follow-up program that includes LS molecular analysis, PV screening with NGS technology, and cascade screening. The goal is to improve LS ascertainment in light of the growing burden of early-onset CRC, particularly in low- and middle-income countries. Abstract Identification of germline pathogenic variants (PV) predisposing to Lynch syndrome (LS) is an important step for effective use of cascade screening of extended at-risk lineages, leading to reduced morbidity and mortality due to colorectal cancer (CRC). As a general rule, however, next generation sequencing (NGS, either of gene panels or whole exomes) is relatively expensive and unaffordable for general clinical use. In resource-poor settings, performing NGS testing on an entire cohort of CRC patients, even if limited to those under 50 or 60 years of age, still places an enormous burden on limited resources. Although family history can be a good indicator for LS testing, identifying at-risk family members and offering cascade screening may not benefit many patients/probands without an obvious family history. This article presents a novel program called Modified Ascertainment and follow-up Program (MAP) with a scoring model for LS ascertainment and molecular screening by NGS with diagnosis confirmation of PV and cascade screening. The goal is to improve LS ascertainment in light of the growing burden of early-onset CRC, particularly in low- and middle-income countries. Through MAP, judiciously applied molecular genetics will improve identification of PV predisposing to LS and cascade screening.
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Affiliation(s)
- Ramadhani Chambuso
- Colorectal Cancer Research Group, Division of Human Genetics, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town 7701, South Africa;
- MRC Unit for Genomic and Precision Medicine, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town 7701, South Africa
- Correspondence:
| | - Barbara Robertson
- Division of Radiation Oncology, Department of Radiation Medicine, Groote Schuur Hospital, University of Cape Town, Cape Town 7945, South Africa;
| | - Raj Ramesar
- Colorectal Cancer Research Group, Division of Human Genetics, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town 7701, South Africa;
- MRC Unit for Genomic and Precision Medicine, Division of Human Genetics, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town 7701, South Africa
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McCabe M, Perner Y, Magobo R, Magangane P, Mirza S, Penny C. Microsatellite Instability assessment in Black South African Colorectal Cancer patients reveal an increased incidence of suspected Lynch syndrome. Sci Rep 2019; 9:15019. [PMID: 31636305 PMCID: PMC6803663 DOI: 10.1038/s41598-019-51316-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 09/17/2019] [Indexed: 12/12/2022] Open
Abstract
Microsatellite Instability (MSI) is a hallmark of colorectal cancer (CRC) and occurs in 15–16% of CRC. Molecular biological information of CRC in South Africa (SA) is largely unrecorded. This study was undertaken to determine the frequency of MSI, with particular reference to Lynch syndrome (LS) with a view to improve surveillance and prevention strategies. This was a retrospective study on CRC samples diagnosed between 2011–2015 at Charlotte Maxeke Johannesburg Academic Hospital (CMJAH). Samples diagnosed between 2011–2012 were screened for MSI by PCR and mismatch repair (MMR) immunohistochemistry (IHC), and additional BRAFV600E mutational analysis performed. T-tests, Fischer’s exact and Chi square statistical tests were applied. Twelve percent of patients displayed MSI, with increased frequency in black (15%) versus other ethnic group (OEG) (8%) patients. MSI patients were significantly younger than microsatellite stable (MSS) patients, however when stratified by ethnicity, black patients were predominantly younger (median age: 47), with increased MSH2/6 loss, and no BRAF mutations. These findings suggest a large proportion of young black SA CRC patients develop via the LS pathway due to earlier age onset and predominant MSH2/6 protein loss. SA patients of other ethnicities appear to follow the more well established sporadic MSI pathway.
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Affiliation(s)
- M McCabe
- Department of Anatomical Pathology, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Johannesburg, 2193, South Africa.
| | | | - R Magobo
- Department of Anatomical Pathology, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Johannesburg, 2193, South Africa
| | - P Magangane
- Department of Anatomical Pathology, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Johannesburg, 2193, South Africa
| | - S Mirza
- Department of Internal Medicine, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Johannesburg, 2193, South Africa
| | - C Penny
- Department of Internal Medicine, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Johannesburg, 2193, South Africa
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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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Bruwer Z, Futter M, Ramesar R. A mobile colonoscopic unit for lynch syndrome: trends in surveillance uptake and patient experiences of screening in a developing country. J Genet Couns 2013; 22:125-37. [PMID: 23299947 DOI: 10.1007/s10897-012-9523-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 06/21/2012] [Indexed: 01/01/2023]
Abstract
The Genetic and Endoscopic Surveillance Clinic is an annual outreach service offering accessible colonoscopic surveillance to known families with Lynch syndrome living in remote areas of the Western and Northern Cape Province of South Africa. Unfortunately attendance at this outreach clinic has been declining over several years and fewer than a quarter of participants, attending for surveillance, have been adherent with all their recommended screening appointments. Concerns exist for non-adherent individuals as screening can prevent colorectal cancer by removing the precancerous lesion or enabling the treatment of a malignancy at an early stage. This study explored the experience of surveillance from both the non-adherers' and adherers' perspectives and identified unique factors affecting attendance at the outreach clinic. Rates of compliance are calculated for 191 mutation-positive cases of Lynch syndrome, using strict attendance criteria, and compared to figures obtained from self-reported attendance. Non-compliance was under-reported and compliance was exaggerated when basing data on self-reported adherence to recommendations. Specific characteristics of the outreach clinic affecting compliance are identified and recommendations are made to facilitate improvements to the service. These improvements can result in increased compliance with screening regimens and ultimately reduce cancer-related mortality.
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Affiliation(s)
- Zandrè Bruwer
- MRC/UCT Human Genetics Research Unit, Division of Human Genetics, Institute for Infectious Diseases and Molecular Medicine, University of Cape Town and Groote Schuur Hospital, Cape Town, South Africa.
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Cancer risk in a cohort of subjects carrying a single mismatch repair gene mutation. Fam Cancer 2009; 8:519-23. [DOI: 10.1007/s10689-009-9281-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Accepted: 08/03/2009] [Indexed: 01/21/2023]
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Stupart DA, Goldberg PA, Algar U, Ramesar R. Surveillance colonoscopy improves survival in a cohort of subjects with a single mismatch repair gene mutation. Colorectal Dis 2009; 11:126-30. [PMID: 19143775 DOI: 10.1111/j.1463-1318.2008.01702.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
OBJECTIVE Previous studies have shown a benefit for surveillance colonoscopy in heterogeneous groups of subjects with suspected or proven hereditary nonpolyposis colon cancer. The aim of this study was to investigate whether surveillance colonoscopy improves the survival in subjects who all carry a single mismatch repair gene defect. METHOD This is a prospective cohort study of 178 subjects who carry a mutation of the MLH1 gene in exon 13 (C1528T). They were offered surveillance colonoscopy between 1988 and 2006, and were followed up until September 2007. RESULTS One hundred and twenty-nine subjects underwent surveillance colonoscopy, and 49 declined. After a median follow up of 5 years, colorectal cancer was diagnosed in 14/129 (11%) subjects in the surveillance group and 13/49 (27%) in the nonsurveillance group (P = 0.019). Cancers in the surveillance group were at an earlier stage than in the nonsurveillance group (P = 0.032). Death from colorectal cancer occurred in three of 129 (2%) subjects in the surveillance group, and six of 49 (12%) in the nonsurveillance group (P = 0.021). The Kaplan-Meyer estimates for median survival from birth were 78 years in the surveillance group, and 55 years in the nonsurveillance group (P = 0.024). The Kaplan-Meyer estimates for median colorectal cancer-free survival from birth were 73 years in the surveillance group and 47 years in the nonsurveillance group (P = 0.0089). CONCLUSION Surveillance colonoscopy was associated with improved overall and colorectal cancer-related survival in subjects carrying a single mismatch repair gene mutation.
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Affiliation(s)
- D A Stupart
- Department of Surgery, University of Cape Town and Groote Schuur Hospital, Cape Town, South Africa.
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Blokhuis MM, Goldberg PA, Pietersen GE, Algar U, Vorster AA, Govender D, Ramesar RS. The extracolonic cancer spectrum in females with the common ‘South African’ hMLH1 c.C1528T mutation. Fam Cancer 2007; 7:191-8. [DOI: 10.1007/s10689-007-9174-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Accepted: 11/19/2007] [Indexed: 01/08/2023]
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Anderson DW, Goldberg PA, Algar U, Felix R, Ramesar RS. Mobile colonoscopic surveillance provides quality care for hereditary nonpolyposis colorectal carcinoma families in South Africa. Colorectal Dis 2007; 9:509-14. [PMID: 17477847 DOI: 10.1111/j.1463-1318.2006.01172.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND It is difficult to provide a colonoscopic surveillance service for at-risk family members with hereditary nonpolyposis colorectal carcinoma when many of those family members live in a remote area of South African far from endoscopic services. A mobile surveillance programme was established to service these individuals. OBJECTIVE The aim of this study was to compare the quality of the mobile service to that provided in established endoscopy units. METHOD Ninety-one asymptomatic subjects with known disease-causing mutations underwent 259 colonoscopies. Of these, 171 colonoscopies were performed by a mobile colonoscopy service in small rural hospitals and 88 in established endoscopy units. The quality of the colonoscopic services was measured by completion rate, the rate of detection of colonoscopic abnormalities, histopathological analyses of biopsies, surgical intervention and colorectal cancer deaths. RESULTS The caecum was reached in 96% of all colonoscopies. A significant lesion was detected in 8.8% of colonoscopies. There was no difference in the rate of complete colonoscopy and detection rate of lesions in the established units and the mobile service (both P = 0.6). The rate of detection of early adenocarcinomas was similar (P = 0.17). The colonoscopic screening/surveillance programme meets international standards with a high accuracy (95.75%) and negative predictive value (100%). CONCLUSION The mobile service provides access to colonoscopy in remote areas without compromising the quality of service.
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Affiliation(s)
- D W Anderson
- Colorectal Unit, Department of Surgery, Institute for Infectious Diseases and Molecular Medicine, University of Cape Town and Groote Schuur Hospital, Cape Town, South Africa
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Felix R, Bodmer W, Fearnhead NS, van der Merwe L, Goldberg P, Ramesar RS. GSTM1 and GSTT1 polymorphisms as modifiers of age at diagnosis of hereditary nonpolyposis colorectal cancer (HNPCC) in a homogeneous cohort of individuals carrying a single predisposing mutation. Mutat Res 2007; 602:175-81. [PMID: 17087981 DOI: 10.1016/j.mrfmmm.2006.09.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Revised: 09/08/2006] [Accepted: 09/19/2006] [Indexed: 11/26/2022]
Abstract
The variability in phenotype that occurs for so-called 'single-gene disorders' may be because of germline alterations in numerous primary and "modifier" genes. Within HNPCC families harbouring the same primary predisposing mutation, differences exist in the site of cancer, age of onset of disease symptoms and, consequently, survival until diagnosis of disease. The current study investigated a cohort of 129 individuals, from 13 different families, who harbour the identical nonsense mutation (C1528T) in the hMLH1 gene, predisposing them primarily to Lynch I syndrome. This cohort was screened for previously described polymorphisms in the glutathione-S-transferase genes, viz. GSTT1 and GSTM1. Male null carriers for both GSTT1 and GSTM1 were approximately three times more at risk of developing cancer at an earlier age when compared to non-null males. This work, particularly because of the relatively large "homogeneous" primary mutation cohort, provides evidence that genotypic changes distinct from the primary 'HNPCC-causing' mutation, influence the survival period until diagnosis of disease. It provides an impetus for expanding the study to include a wider range of candidate modifier genes. Such work may potentially lead to the development of individualised interval screening regimens for individuals with varying modifier genotypes--an attractive option in a resource-poor country.
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Affiliation(s)
- Rebecca Felix
- MRC Research Unit for Human Genetics, Division of Human Genetics, Institute for Infectious Diseases and Molecular Medicine, Faculty of Health Sciences, University of Cape Town Medical School, Anzio Road, Observatory 7925, South Africa
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Mecklin JP, Järvinen HJ. Surveillance in Lynch syndrome. Fam Cancer 2005; 4:267-71. [PMID: 16136388 DOI: 10.1007/s10689-005-1475-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2004] [Accepted: 01/26/2005] [Indexed: 12/21/2022]
Abstract
The major aim of surveillance in Lynch syndrome is to diagnose malignant or premalignant lesions at the asymptomatic stage by regular checkups, particularly in the large bowel. Therefore, screening for colorectal adenomas and carcinomas by regular colonoscopies is the main topic of the present review. However, it should be remembered, that primary prevention - whether through the use of chemoprevention or the promotion of a healthy life-style may form a significant part of such surveillance in the future. Observational studies indicate that the adenoma carcinoma sequence is the main pathway in the development of colorectal cancer in Lynch syndrome. A colonoscopy every 1-3 years starting at age 20 to 25 years and the removal of observed adenomas is recommended for individuals known to have Lynch syndrome associated mutations. The incidence of colorectal cancer in family branches screened this way is lower than that in past unscreened generations. The screening of other malignancies associated with Lynch syndrome is more complex. Screening for endometrial cancer has recommended previously, but no benefits have been shown in recent studies. The value of screening for other extracolonic cancers remains also uncertain.
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Affiliation(s)
- Jukka-Pekka Mecklin
- Department of Surgery, Jyväskylä Central Hospital, 40620, Jyväskylä, Finland.
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