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Brignola C, Volorio S, De Vecchi G, Zaffaroni D, Dall’Olio V, Mariette F, Sardella D, Capra F, Signoroni S, Rausa E, Vitellaro M, Pensotti V, Ricci MT. De novo germline pathogenic variant in Lynch Syndrome: A rare event or the tip of the iceberg? TUMORI JOURNAL 2024; 110:69-73. [PMID: 37691472 PMCID: PMC10851626 DOI: 10.1177/03008916231197113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/28/2023] [Accepted: 08/08/2023] [Indexed: 09/12/2023]
Abstract
Lynch Syndrome is an autosomal dominant cancer predisposition syndrome caused by germline pathogenic variants or epimutation in one of the DNA mismatch repair genes. De novo pathogenic variants in mismatch repair genes have been described as a rare event in Lynch Syndrome (1-5%), although the prevalence of de novo pathogenic variants in Lynch Syndrome is probably underestimated. The de novo pathogenic variant was identified in a 26-year-old woman diagnosed with an adenocarcinoma of the caecum with mismatch repair protein deficiency at immunohistochemistry and a synchronous neuroendocrine tumor of the appendix with normal expression of mismatch repair proteins. DNA testing revealed deletion of exon 6 of the MLH1 gene. It appeared to be a de novo event, as the deletion was not detected in the patient's parents. The presence of a mosaicism in the patient was excluded and haplotype analysis demonstrated the paternal origin of the chromosome harboring the deletion. The de novo deletion probably originated either from a very early postzygotic or a single prezygotic mutational event, or from a gonadal mosaicism. In conclusion, the identification of de novo pathogenic variants is crucial to allow proper genetic counseling and appropriate management of the patient's family.
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Affiliation(s)
- Clorinda Brignola
- Unit of Hereditary Digestive Tract Tumors, Department of Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Sara Volorio
- Cancer Genetics Test Laboratory, Cogentech s.r.l. Società Benefit a Socio Unico, Milan, Italy
| | - Giovanna De Vecchi
- Cancer Genetics Test Laboratory, Cogentech s.r.l. Società Benefit a Socio Unico, Milan, Italy
| | - Daniela Zaffaroni
- Unit of Hereditary Digestive Tract Tumors, Department of Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Valentina Dall’Olio
- Cancer Genetics Test Laboratory, Cogentech s.r.l. Società Benefit a Socio Unico, Milan, Italy
| | - Frederique Mariette
- Cancer Genetics Test Laboratory, Cogentech s.r.l. Società Benefit a Socio Unico, Milan, Italy
| | - Domenico Sardella
- Cancer Genetics Test Laboratory, Cogentech s.r.l. Società Benefit a Socio Unico, Milan, Italy
| | - Fabio Capra
- Cancer Genetics Test Laboratory, Cogentech s.r.l. Società Benefit a Socio Unico, Milan, Italy
| | - Stefano Signoroni
- Unit of Hereditary Digestive Tract Tumors, Department of Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Emanuele Rausa
- Unit of Hereditary Digestive Tract Tumors, Department of Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Marco Vitellaro
- Unit of Hereditary Digestive Tract Tumors, Department of Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Valeria Pensotti
- Cancer Genetics Test Laboratory, Cogentech s.r.l. Società Benefit a Socio Unico, Milan, Italy
| | - Maria Teresa Ricci
- Unit of Hereditary Digestive Tract Tumors, Department of Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
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Du K, Ren J, Zheng G, Li S, Chen L, Hou W, Duan W, Huang D, Zhang H, Feng F, Zheng J. Variation of the ileocolic artery and superior mesenteric artery in a patient with right-sided colon cancer with Lynch syndrome: a case report. ANNALS OF TRANSLATIONAL MEDICINE 2022; 10:939. [PMID: 36172100 PMCID: PMC9511195 DOI: 10.21037/atm-22-3012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Accepted: 08/30/2022] [Indexed: 11/06/2022]
Abstract
Background Complete mesangectomy and central vascular detachment are the core elements of laparoscopic right hemicolectomy. Failure to identify vascular variations in patients undergoing laparoscopic right hemicolectomy can result in unwanted bleeding, a prolonged surgical time, transfer to open surgery, and an elevated risk of postoperative complications. In this case report, we describe a new vascular variation that has not yet been reported in the literature. Parallelly vascular variation and the management of vessels in key areas are essential for successful surgery. Case Description The patient was a 32-year-old female who was referred to the department of gastrointestinal surgery of our hospital due to intermittent abdominal pain accompanied by changes in stool habits for 3 months. She had not experienced other symptoms. Physical examination revealed mild tenderness in the right lower abdomen. Subsequently, she underwent laparoscopic radical right hemicolectomy for ascending colon cancer under general anesthesia in our hospital. Preoperative abdominal contrast-enhanced computed tomography (CT) and intraoperative photos confirmed that there were two ileocolic arteries derived from the superior mesenteric artery (SMA). On the other side, the SMA and superior mesenteric vein (SMV) were found to be accompanied like "X"-shaped variant. The final surgical pathological diagnosis was pT3N1aM0 adenocarcinoma of the ascending colon. Given the patient's family history of colon and uterine cancer combined with the results of immunohistochemical staining and next-generation sequencing, we concluded that she had Lynch syndrome (LS). Conclusions This report describes the first case of simultaneous variation of the ileocolic artery (ICA) and SMA in a female patient with colon cancer. This type of vascular variation should be fully recognized by surgeons in order to avoid unnecessary intraoperative bleeding.
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Affiliation(s)
- Kunli Du
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Air Force Medical University, Xi'an, China
| | - Jiahui Ren
- Department of Anus and Intestine Surgery, Xi'an Mayinglong Anorectal Hospital, Xi'an, China
| | - Gaozan Zheng
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Air Force Medical University, Xi'an, China
| | - Shisen Li
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Air Force Medical University, Xi'an, China
| | - Ling Chen
- Department of Pathology, The First Affiliated Hospital of Air Force Medical University, Xi'an, China
| | - Wei Hou
- Department of Radiology, The First Affiliated Hospital of Air Force Medical University, Xi'an, China
| | | | | | | | - Fan Feng
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Air Force Medical University, Xi'an, China
| | - Jianyong Zheng
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Air Force Medical University, Xi'an, China
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Lynch syndrome caused by a novel deletion of the promoter and exons 1-13 of MLH1 gene. Cancer Genet 2022; 262-263:91-94. [DOI: 10.1016/j.cancergen.2022.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 12/26/2021] [Accepted: 01/20/2022] [Indexed: 11/20/2022]
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A de novo pathogenic variant in the MSH6 gene in a 52 years-old woman. Fam Cancer 2021; 21:319-324. [PMID: 34519923 DOI: 10.1007/s10689-021-00274-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 08/29/2021] [Indexed: 10/20/2022]
Abstract
Lynch syndrome (LS) is a condition which predisposes individuals primarily to early-onset colorectal and endometrial cancer. LS is characterized by a germline pathogenic variant in one of the MMR (MisMatch Repair) gene, inducing a phenotype of microsatellite instability in the tumor, which may be associated with a loss of expression of MMR proteins detected by standard immunohistochemistry on tumor tissue. Most of the time, LS is inherited from a parent in whom the condition may not be known due to incomplete penetrance, but de novo pathogenic variant is a rare occurrence. Here, we describe the case of a 52-year-old woman with no family history of LS, referred to the genetics department for colorectal cancer at the age of 50. Genetic analysis revealed a de novo germline pathogenic variant in the MSH6 gene. To date, this case is only the second report of a de novo pathogenic variant in the MSH6 gene in Lynch syndrome. De novo mutations have been extensively studied over the past years, but little is known about their origin and mechanism of occurrence in MMR genes. However, knowledge of mutation status allows better cancer risk management for the patient and an appropriate genetic testing and counseling for her family.
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Win AK, Lindor NM, Winship I, Tucker KM, Buchanan DD, Young JP, Rosty C, Leggett B, Giles GG, Goldblatt J, Macrae FA, Parry S, Kalady MF, Baron JA, Ahnen DJ, Marchand LL, Gallinger S, Haile RW, Newcomb PA, Hopper JL, Jenkins MA. Risks of colorectal and other cancers after endometrial cancer for women with Lynch syndrome. J Natl Cancer Inst 2013; 105:274-9. [PMID: 23385444 DOI: 10.1093/jnci/djs525] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Lynch syndrome is an autosomal dominantly inherited disorder caused by germline mutations in DNA mismatch repair (MMR) genes. Previous studies have shown that MMR gene mutation carriers are at increased risk of colorectal, endometrial, and several other cancers following an initial diagnosis of colorectal cancer. We estimated cancer risks following an endometrial cancer diagnosis for women carrying MMR gene mutations. METHODS We obtained data from the Colon Cancer Family Registry for a cohort of 127 women who had a diagnosis of endometrial cancer and who carried a mutation in one of four MMR genes (30 carried a mutation in MLH1, 72 in MSH2, 22 in MSH6, and 3 in PMS2). We used the Kaplan-Meier method to estimate 10- and 20-year cumulative risks for each cancer. We estimated the age-, country-, and calendar period-specific standardized incidence ratios (SIRs) for each cancer, compared with the general population. RESULTS Following endometrial cancer, women carrying MMR gene mutations had the following 20-year risks of other cancer cancers: colorectal cancer (48%, 95% confidence interval [CI] = 35% to 62%); cancer of the kidney, renal pelvis, or ureter (11%, 95% CI = 3% to 20%); urinary bladder cancer (9%, 95% CI = 2% to 17%); and breast cancer (11%, 95% CI = 4% to 19%). Compared with the general population, these women were at statistically significantly elevated risks of colorectal cancer (SIR = 39.9, 95% CI = 27.2 to 58.3), cancer of the kidney, renal pelvis, or ureter (SIR = 28.3, 95% CI = 11.9 to 48.6), urinary bladder cancer (SIR = 24.3, 95% CI = 8.56 to 42.9), and breast cancer (SIR = 2.51, 95% CI = 1.17 to 4.14). CONCLUSIONS Women with Lynch syndrome who are diagnosed with endometrial cancer have increased risks of several cancers, including breast cancer.
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Affiliation(s)
- Aung Ko Win
- Centre for Molecular, Environmental, Genetic and Analytic Epidemiology, Melbourne School of Population Health, Level 3, 207 Bouverie St, University of Melbourne, VIC 3010 Australia
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Airaud F, Küry S, Valo I, Maury I, Bonneau D, Ingster O, Bezieau S. A de novo germline MLH1 mutation in a Lynch syndrome patient with discordant immunohistochemical and molecular biology test results. World J Gastroenterol 2012; 18:5635-9. [PMID: 23112559 PMCID: PMC3482653 DOI: 10.3748/wjg.v18.i39.5635] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 06/14/2012] [Accepted: 07/18/2012] [Indexed: 02/06/2023] Open
Abstract
We describe a patient with a Homo sapiens mutL homolog 1 (MLH1)-associated Lynch syndrome with previous diagnoses of two distinct primary cancers: a sigmoid colon cancer at the age of 39 years, and a right colon cancer at the age of 50 years. The mutation identified in his blood and buccal cells, c.1771delG, p.Asp591Ilefs*25, appears to be a de novo event, as it was not transmitted by either of his parents. This type of de novo event is rare in MLH1 as only three cases have been reported in the literature so far. Furthermore, the discordant results observed between replication error phenotyping and immunohistochemistry highlight the importance of the systematic use of both pre-screening tests in the molecular diagnosis of Lynch syndrome.
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Win AK, Lindor NM, Young JP, Macrae FA, Young GP, Williamson E, Parry S, Goldblatt J, Lipton L, Winship I, Leggett B, Tucker KM, Giles GG, Buchanan DD, Clendenning M, Rosty C, Arnold J, Levine AJ, Haile RW, Gallinger S, Le Marchand L, Newcomb PA, Hopper JL, Jenkins MA. Risks of primary extracolonic cancers following colorectal cancer in lynch syndrome. J Natl Cancer Inst 2012; 104:1363-72. [PMID: 22933731 DOI: 10.1093/jnci/djs351] [Citation(s) in RCA: 160] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Lynch syndrome is a highly penetrant cancer predisposition syndrome caused by germline mutations in DNA mismatch repair (MMR) genes. We estimated the risks of primary cancers other than colorectal cancer following a diagnosis of colorectal cancer in mutation carriers. METHODS We obtained data from the Colon Cancer Family Registry for 764 carriers of an MMR gene mutation (316 MLH1, 357 MSH2, 49 MSH6, and 42 PMS2), who had a previous diagnosis of colorectal cancer. The Kaplan-Meier method was used to estimate their cumulative risk of cancers 10 and 20 years after colorectal cancer. We estimated the age-, sex-, country- and calendar period-specific standardized incidence ratios (SIRs) of cancers following colorectal cancer, compared with the general population. RESULTS Following colorectal cancer, carriers of MMR gene mutations had the following 10-year risk of cancers in other organs: kidney, renal pelvis, ureter, and bladder (2%, 95% confidence interval [CI] = 1% to 3%); small intestine, stomach, and hepatobiliary tract (1%, 95% CI = 0.2% to 2%); prostate (3%, 95% CI = 1% to 5%); endometrium (12%, 95% CI = 8% to 17%); breast (2%, 95% CI = 1% to 4%); and ovary (1%, 95% CI = 0% to 2%). They were at elevated risk compared with the general population: cancers of the kidney, renal pelvis, and ureter (SIR = 12.54, 95% CI = 7.97 to 17.94), urinary bladder (SIR = 7.22, 95% CI = 4.08 to 10.99), small intestine (SIR = 72.68, 95% CI = 39.95 to 111.29), stomach (SIR = 5.65, 95% CI = 2.32 to 9.69), and hepatobiliary tract (SIR = 5.94, 95% CI = 1.81 to 10.94) for both sexes; cancer of the prostate (SIR = 2.05, 95% CI = 1.23 to 3.01), endometrium (SIR = 40.23, 95% CI = 27.91 to 56.06), breast (SIR = 1.76, 95% CI = 1.07 to 2.59), and ovary (SIR = 4.19, 95% CI = 1.28 to 7.97). CONCLUSION Carriers of MMR gene mutations who have already had a colorectal cancer are at increased risk of a greater range of cancers than the recognized spectrum of Lynch syndrome cancers, including breast and prostate cancers.
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Affiliation(s)
- Aung Ko Win
- Centre for Molecular, Environmental, Genetic and Analytic Epidemiology, Melbourne School of Population Health, Level 3, 207 Bouverie Street, The University of Melbourne, VIC 3010, Australia
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Win AK, Young JP, Lindor NM, Tucker KM, Ahnen DJ, Young GP, Buchanan DD, Clendenning M, Giles GG, Winship I, Macrae FA, Goldblatt J, Southey MC, Arnold J, Thibodeau SN, Gunawardena SR, Bapat B, Baron JA, Casey G, Gallinger S, Le Marchand L, Newcomb PA, Haile RW, Hopper JL, Jenkins MA. Colorectal and other cancer risks for carriers and noncarriers from families with a DNA mismatch repair gene mutation: a prospective cohort study. J Clin Oncol 2012; 30:958-64. [PMID: 22331944 DOI: 10.1200/jco.2011.39.5590] [Citation(s) in RCA: 231] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
PURPOSE To determine whether cancer risks for carriers and noncarriers from families with a mismatch repair (MMR) gene mutation are increased above the risks of the general population. PATIENTS AND METHODS We prospectively followed a cohort of 446 unaffected carriers of an MMR gene mutation (MLH1, n = 161; MSH2, n = 222; MSH6, n = 47; and PMS2, n = 16) and 1,029 their unaffected relatives who did not carry a mutation every 5 years at recruitment centers of the Colon Cancer Family Registry. For comparison of cancer risk with the general population, we estimated country-, age-, and sex-specific standardized incidence ratios (SIRs) of cancer for carriers and noncarriers. RESULTS Over a median follow-up of 5 years, mutation carriers had an increased risk of colorectal cancer (CRC; SIR, 20.48; 95% CI, 11.71 to 33.27; P < .001), endometrial cancer (SIR, 30.62; 95% CI, 11.24 to 66.64; P < .001), ovarian cancer (SIR, 18.81; 95% CI, 3.88 to 54.95; P < .001), renal cancer (SIR, 11.22; 95% CI, 2.31 to 32.79; P < .001), pancreatic cancer (SIR, 10.68; 95% CI, 2.68 to 47.70; P = .001), gastric cancer (SIR, 9.78; 95% CI, 1.18 to 35.30; P = .009), urinary bladder cancer (SIR, 9.51; 95% CI, 1.15 to 34.37; P = .009), and female breast cancer (SIR, 3.95; 95% CI, 1.59 to 8.13; P = .001). We found no evidence of their noncarrier relatives having an increased risk of any cancer, including CRC (SIR, 1.02; 95% CI, 0.33 to 2.39; P = .97). CONCLUSION We confirmed that carriers of an MMR gene mutation were at increased risk of a wide variety of cancers, including some cancers not previously recognized as being a result of MMR mutations, and found no evidence of an increased risk of cancer for their noncarrier relatives.
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van Vliet CM, Dowty JG, van Vliet JL, Smith L, Mead LJ, Macrae FA, St John DJB, Giles GG, Southey MC, Jenkins MA, Velan GM, Hopper JL. Dependence of colorectal cancer risk on the parent-of-origin of mutations in DNA mismatch repair genes. Hum Mutat 2011; 32:207-12. [PMID: 21120946 DOI: 10.1002/humu.21408] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 10/31/2010] [Indexed: 11/08/2022]
Abstract
Genetic diseases associated with dynamic mutations in microsatellite DNA often display parent-of-origin effects (POEs) in which the risk of disease depends on the sex of the parent from whom the disease allele was inherited. Carriers of germline mutations in mismatch repair (MMR) genes have high risks of colorectal carcinoma (CRC). We investigated whether these risks depend on the parent-of-origin of the mutation. We studied 422 subjects, including 89 MMR gene mutation carriers, from 17 population-based families who were each recruited via a CRC case diagnosed before age 45 years and found to carry a MMR gene mutation. The POE hazard ratio (HR(POE)), defined to be the CRC incidence for carriers with maternally derived mutations divided by the corresponding paternal incidence, was estimated using a novel application of modified segregation analysis. HR(POE) (95% confidence interval) was estimated to be 3.2 (1.1-9.8) for males (P = 0.03) and 0.8 (0.2-2.8) for females (P = 0.5) and the corresponding cumulative risks to age 80 years were 88% (54%-100%) for male carriers with maternally derived mutations and 38-48% for all other carriers. If confirmed by larger studies, these results will have important implications for the etiology of CRC and for the clinical management of MMR gene mutation carriers.
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Affiliation(s)
- Christine M van Vliet
- Centre for Molecular, Environmental, Genetic, Analytic Epidemiology, The University of Melbourne, Victoria 3010, Australia
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Al-Sukhni W, Aronson M, Gallinger S. Hereditary colorectal cancer syndromes: familial adenomatous polyposis and lynch syndrome. Surg Clin North Am 2008; 88:819-44, vii. [PMID: 18672142 DOI: 10.1016/j.suc.2008.04.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Familial colorectal cancer (CRC) accounts for 10% to 20% of all cases of CRC. Two major autosomal dominant forms of heritable CRC are familial adenomatous polyposis (FAP) and Lynch syndrome (also known as hereditary nonpolyposis colorectal cancer). Along with the risk for CRC, both syndromes are associated with elevated risk for other tumors. Improved understanding of the genetic basis of these diseases has not only facilitated the identification and screening of at-risk individuals and the development of prophylactic or early-stage intervention strategies but also provided better insight into sporadic CRC. This article reviews the clinical and genetic characteristics of FAP and Lynch syndrome, recommended screening and surveillance practices, and appropriate surgical and nonsurgical interventions.
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Affiliation(s)
- Wigdan Al-Sukhni
- Division of General Surgery, Department of Surgery, University of Toronto, 1225-600 University Avenue, Toronto, Ontario, Canada M5G 1X5.
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Wong EM, Tesoriero AA, Pupo GM, McCredie MRE, Giles GG, Hopper JL, Mann GJ, Goldgar DE, Southey MC. Is MSH2 a breast cancer susceptibility gene? Fam Cancer 2007; 7:151-5. [PMID: 17922223 DOI: 10.1007/s10689-007-9162-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Accepted: 09/11/2007] [Indexed: 11/25/2022]
Abstract
Mutations in the DNA mismatch repair gene MSH2 lead to increased replication error and microsatellite instability and account for a substantial proportion of hereditary non-polyposis colorectal cancer (Lynch syndrome). A recent international collaborative genome-wide linkage scan (GWS) for breast cancer susceptibility loci found some evidence for there being a breast cancer susceptibility gene in a genomic region on chromosome 2p close to MSH2. We sought to investigate the possibility that mutations in MSH2 might explain the multiple cases of breast cancer in some families that were included in the international GWS. DNA samples from the affected probands of 59 multiple-case breast cancer families, many of whom gave LOD scores >0.5 in the MSH2 region, were screened for large genomic alterations in MSH2 via the Multiplex Ligation-dependent Probe Amplification (MLPA) assay and for coding region mutations via exonic sequencing. Several of the families also contained cases of colorectal cancer in addition to breast cancer and had been included in the GWS that had identified a positive LOD score on chromosome 2p. Using MLPA, c.1236C > T was identified in one proband but this variant was not predicted to create an alternate acceptor/donor site within exon 7 MSH2 using in silico analyses. A c.1734T > C was identified in a second proband via exonic sequencing but testing of the variant in other family members did not support segregation of this variant with disease. Extensive screening of 59 multiple-case breast cancer families did not identify any coding region mutations or larger genomic alterations in MSH2 that might implicate MSH2 as a breast cancer susceptibility gene.
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Affiliation(s)
- Ee Ming Wong
- Genetic Epidemiology Laboratory, Department of Pathology, The University of Melbourne, Melbourne 3010, Australia
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Mead LJ, Jenkins MA, Young J, Royce SG, Smith L, St John DJB, Macrae F, Giles GG, Hopper JL, Southey MC. Microsatellite instability markers for identifying early-onset colorectal cancers caused by germ-line mutations in DNA mismatch repair genes. Clin Cancer Res 2007; 13:2865-9. [PMID: 17504984 DOI: 10.1158/1078-0432.ccr-06-2174] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Microsatellite instability (MSI) testing of colorectal cancer tumors is used as a screening tool to identify patients most likely to be mismatch repair (MMR) gene mutation carriers. We wanted to examine which microsatellite markers currently used to detect MSI best predict early-onset colorectal cancer caused by germ-line mutations in MMR genes. EXPERIMENTAL DESIGN Invasive primary tumors from a population-based sample of 107 cases of colorectal cancer diagnosed before age 45 years and tested for germ-line mutations in MLH1, MSH2, MSH6, and PMS2 and MMR protein expression were screened for MSI using the National Cancer Institute panel and an expanded 10-microsatellite marker panel. RESULTS The National Cancer Institute five-marker panel system scored 31 (29%) as (NCI)MSI-High, 13 (12%) as (NCI)MSI-Low, and 63 (59%) as (NCI)MS-Stable. The 10-marker panel classified 18 (17%) as (10)MSI-High, 17 (16%) as (10)MSI-Low, and 72 (67%) as (10)MS-Stable. Of the 26 cancers that lacked the expression of at least one MMR gene, 24 (92%) were positive for some level of MSI (using either microsatellite panel). The mononucleotide repeats Bat26, Bat40, and Myb were unstable in all (10)MSI-High cancers and all MLH1 and MSH2 mutation carriers (100% sensitive). Bat40 and Bat25 were unstable in all tumors of MSH6 mutation carriers (100% sensitive). Bat40 was unstable in all MMR gene mutation carriers (100% sensitive). By incorporating seven mononucleotide repeats markers into the 10-marker panel, we were able to distinguish the carriers of MSH6 mutations (all scored (10)MSI-Low) from the MLH1 and MSH2 mutation carriers (all scored (10)MSI-High). CONCLUSIONS In early-onset colorectal cancer, a microsatellite panel containing a high proportion of mononuclear repeats can distinguish between tumors caused by MLH1 and MSH2 mutations from those caused by MSH6 mutations.
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Affiliation(s)
- Leeanne J Mead
- Genetic Epidemiology Laboratory, Department of Pathology, The University of Melbourne, Melbourne, Victoria, Australia
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