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Fisher JL, Hale AJ, Gollard R. Tri-occurrence of attenuated familial adenomatous polyposis, Lynch syndrome, and hereditary breast and ovarian cancer: A case report with implications for treatment and surveillance. Meta Gene 2022. [DOI: 10.1016/j.mgene.2021.101001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Garza-Rodríguez ML, Treviño V, Pérez-Maya AA, Rodríguez-Gutiérrez HF, González-Escamilla M, Elizondo-Riojas MÁ, Ramírez-Correa GA, Vidal-Gutiérrez O, Burciaga-Flores CH, Pérez-Ibave DC. Identification of a Novel Pathogenic Rearrangement Variant of the APC Gene Associated with a Variable Spectrum of Familial Cancer. Diagnostics (Basel) 2021; 11:diagnostics11030411. [PMID: 33670908 PMCID: PMC7997431 DOI: 10.3390/diagnostics11030411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 02/05/2021] [Accepted: 02/22/2021] [Indexed: 01/14/2023] Open
Abstract
Familial adenomatous polyposis (FAP) is an autosomal-dominant condition characterized by the presence of multiple colorectal adenomas, caused by germline variants in the adenomatous polyposis coli (APC) gene. More than 300 germline variants have been characterized. The detection of novel variants is important to understand the mechanisms of pathophysiology. We identified a novel pathogenic germline variant using next-generation sequencing (NGS) in a proband patient. The variant is a complex rearrangement (c.422+1123_532-577 del ins 423-1933_423-1687 inv) that generates a complete deletion of exon 5 of the APC gene. To study the variant in other family members, we designed an endpoint PCR method followed by Sanger sequencing. The variant was identified in the proband patient's mother, one daughter, her brother, two cousins, a niece, and a second nephew. In patients where the variant was identified, we found atypical clinical symptoms, including mandibular, ovarian, breast, pancreatic, and gastric cancer. Genetic counseling and cancer prevention strategies were provided for the family. According to the American College of Medical Genetics (ACMG) guidelines, this novel variant is considered a PVS1 variant (very strong evidence of pathogenicity), and it can be useful in association with clinical data for early surveillance and suitable treatment.
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Affiliation(s)
- María Lourdes Garza-Rodríguez
- Centro Universitario Contra el Cáncer (CUCC), Servicio de Oncología, Universidad Autónoma de Nuevo León, Hospital Universitario “Dr. José Eleuterio González”, Nuevo, León 64460, Mexico; (M.L.G.-R.); (H.F.R.-G.); (M.G.-E.); (M.Á.E.-R.); (O.V.-G.)
| | - Víctor Treviño
- Tecnológico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Nuevo, León 64710, Mexico;
| | - Antonio Alí Pérez-Maya
- Departamento de Bioquímica y Medicina Molecular, Facultad de Medicina, Universidad Autónoma de Nuevo León, Nuevo, León 64460, Mexico;
| | - Hazyadee Frecia Rodríguez-Gutiérrez
- Centro Universitario Contra el Cáncer (CUCC), Servicio de Oncología, Universidad Autónoma de Nuevo León, Hospital Universitario “Dr. José Eleuterio González”, Nuevo, León 64460, Mexico; (M.L.G.-R.); (H.F.R.-G.); (M.G.-E.); (M.Á.E.-R.); (O.V.-G.)
| | - Moisés González-Escamilla
- Centro Universitario Contra el Cáncer (CUCC), Servicio de Oncología, Universidad Autónoma de Nuevo León, Hospital Universitario “Dr. José Eleuterio González”, Nuevo, León 64460, Mexico; (M.L.G.-R.); (H.F.R.-G.); (M.G.-E.); (M.Á.E.-R.); (O.V.-G.)
| | - Miguel Ángel Elizondo-Riojas
- Centro Universitario Contra el Cáncer (CUCC), Servicio de Oncología, Universidad Autónoma de Nuevo León, Hospital Universitario “Dr. José Eleuterio González”, Nuevo, León 64460, Mexico; (M.L.G.-R.); (H.F.R.-G.); (M.G.-E.); (M.Á.E.-R.); (O.V.-G.)
| | - Genaro A. Ramírez-Correa
- Department of Molecular Science, UT Health Rio Grande Valley, McAllen, TX 78502, USA;
- Department of Pediatrics, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Oscar Vidal-Gutiérrez
- Centro Universitario Contra el Cáncer (CUCC), Servicio de Oncología, Universidad Autónoma de Nuevo León, Hospital Universitario “Dr. José Eleuterio González”, Nuevo, León 64460, Mexico; (M.L.G.-R.); (H.F.R.-G.); (M.G.-E.); (M.Á.E.-R.); (O.V.-G.)
| | - Carlos Horacio Burciaga-Flores
- Centro Universitario Contra el Cáncer (CUCC), Servicio de Oncología, Universidad Autónoma de Nuevo León, Hospital Universitario “Dr. José Eleuterio González”, Nuevo, León 64460, Mexico; (M.L.G.-R.); (H.F.R.-G.); (M.G.-E.); (M.Á.E.-R.); (O.V.-G.)
- Correspondence: (C.H.B.-F.); or (D.C.P.-I.); Tel.: +52-(81)-83338111 (C.H.B.-F. & D.C.P.-I.)
| | - Diana Cristina Pérez-Ibave
- Centro Universitario Contra el Cáncer (CUCC), Servicio de Oncología, Universidad Autónoma de Nuevo León, Hospital Universitario “Dr. José Eleuterio González”, Nuevo, León 64460, Mexico; (M.L.G.-R.); (H.F.R.-G.); (M.G.-E.); (M.Á.E.-R.); (O.V.-G.)
- Correspondence: (C.H.B.-F.); or (D.C.P.-I.); Tel.: +52-(81)-83338111 (C.H.B.-F. & D.C.P.-I.)
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Hahn MM, de Voer RM, Hoogerbrugge N, Ligtenberg MJL, Kuiper RP, van Kessel AG. The genetic heterogeneity of colorectal cancer predisposition - guidelines for gene discovery. Cell Oncol (Dordr) 2016; 39:491-510. [PMID: 27279102 PMCID: PMC5121185 DOI: 10.1007/s13402-016-0284-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/27/2016] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Colorectal cancer (CRC) is a cumulative term applied to a clinically and genetically heterogeneous group of neoplasms that occur in the bowel. Based on twin studies, up to 45 % of the CRC cases may involve a heritable component. Yet, only in 5-10 % of these cases high-penetrant germline mutations are found (e.g. mutations in APC and DNA mismatch repair genes) that result in a familial aggregation and/or an early onset of the disease. Genome-wide association studies have revealed that another ~5 % of the CRC cases may be explained by a cumulative effect of low-penetrant risk factors. Recent attempts to identify novel genetic factors using whole exome and whole genome sequencing has proven to be difficult since the remaining, yet to be discovered, high penetrant CRC predisposing genes appear to be rare. In addition, most of the moderately penetrant candidate genes identified so far have not been confirmed in independent cohorts. Based on literature examples, we here discuss how careful patient and cohort selection, candidate gene and variant selection, and corroborative evidence may be employed to facilitate the discovery of novel CRC predisposing genes. CONCLUSIONS The picture emerges that the genetic predisposition to CRC is heterogeneous, involving complex interplays between common and rare (inter)genic variants with different penetrances. It is anticipated, however, that the use of large clinically well-defined patient and control datasets, together with improved functional and technical possibilities, will yield enough power to unravel this complex interplay and to generate accurate individualized estimates for the risk to develop CRC.
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Affiliation(s)
- M M Hahn
- Department of Human Genetics, Radboud Institute of Molecular Life Sciences, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - R M de Voer
- Department of Human Genetics, Radboud Institute of Molecular Life Sciences, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - N Hoogerbrugge
- Department of Human Genetics, Radboud Institute of Molecular Life Sciences, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - M J L Ligtenberg
- Department of Human Genetics, Radboud Institute of Molecular Life Sciences, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - R P Kuiper
- Department of Human Genetics, Radboud Institute of Molecular Life Sciences, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - A Geurts van Kessel
- Department of Human Genetics, Radboud Institute of Molecular Life Sciences, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
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The ophthalmic experience: unanticipated primary findings in the era of next generation sequencing. J Genet Couns 2014; 23:588-93. [PMID: 24399093 DOI: 10.1007/s10897-013-9679-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Accepted: 12/02/2013] [Indexed: 10/25/2022]
Abstract
Next generation sequencing (NGS) technology, with the ability to sequence many genomic regions at once, can provide clinicians with increased information, in the form of more mutations detected. Discussions on broad testing technology have largely been focused on incidental findings, or unanticipated results related to diseases beyond the primary indication for testing. By examining multiple genes that could be responsible for the patient's presentation, however, there is also the possibility of unexpected results that are related to the reason genetic testing was ordered. We present a case study where multiple potentially causative mutations were detected using NGS technology. This case raises questions of scientific uncertainty, and has important implications for medical management and secondary studies. Clinicians and genetic counselors should be aware of the potential for increased information to affect one's understanding of genetic risk, and the pre- and post-testing counseling process.
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Cooper DN, Krawczak M, Polychronakos C, Tyler-Smith C, Kehrer-Sawatzki H. Where genotype is not predictive of phenotype: towards an understanding of the molecular basis of reduced penetrance in human inherited disease. Hum Genet 2013; 132:1077-130. [PMID: 23820649 PMCID: PMC3778950 DOI: 10.1007/s00439-013-1331-2] [Citation(s) in RCA: 417] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 06/15/2013] [Indexed: 02/06/2023]
Abstract
Some individuals with a particular disease-causing mutation or genotype fail to express most if not all features of the disease in question, a phenomenon that is known as 'reduced (or incomplete) penetrance'. Reduced penetrance is not uncommon; indeed, there are many known examples of 'disease-causing mutations' that fail to cause disease in at least a proportion of the individuals who carry them. Reduced penetrance may therefore explain not only why genetic diseases are occasionally transmitted through unaffected parents, but also why healthy individuals can harbour quite large numbers of potentially disadvantageous variants in their genomes without suffering any obvious ill effects. Reduced penetrance can be a function of the specific mutation(s) involved or of allele dosage. It may also result from differential allelic expression, copy number variation or the modulating influence of additional genetic variants in cis or in trans. The penetrance of some pathogenic genotypes is known to be age- and/or sex-dependent. Variable penetrance may also reflect the action of unlinked modifier genes, epigenetic changes or environmental factors. At least in some cases, complete penetrance appears to require the presence of one or more genetic variants at other loci. In this review, we summarize the evidence for reduced penetrance being a widespread phenomenon in human genetics and explore some of the molecular mechanisms that may help to explain this enigmatic characteristic of human inherited disease.
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Affiliation(s)
- David N. Cooper
- Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN UK
| | - Michael Krawczak
- Institute of Medical Informatics and Statistics, Christian-Albrechts University, 24105 Kiel, Germany
| | | | - Chris Tyler-Smith
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA UK
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Multiple jejunal cancers resulting from combination of germline APC and MLH1 mutations. Fam Cancer 2012; 11:667-9. [DOI: 10.1007/s10689-012-9561-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Turnbull CL, Bacon AL, Dunlop MG, Farrington SM. In vitro stability of APC gene sequences and the influence of DNA repair status. Mutagenesis 2012; 27:233-8. [PMID: 22294772 DOI: 10.1093/mutage/ger069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
APC is a key 'gatekeeper' gene in colorectal tumorigenesis. The high frequency of APC defects observed in colorectal cancer tissue is the result of selective growth advantage of cells with loss-of-function mutations at that locus. However, mutations may also arise due to inherent sequence instability. Defective DNA mismatch repair (MMR) and base excision repair (BER) also contribute to colorectal carcinogenesis and may compound such instability. To avoid the effect of clonal selective advantage imparted by APC mutation in cancer cells, we assessed in vitro APC mutation frequency in cell lines of lymphoid lineage to investigate the influence of defective MMR and BER. In DNA repair proficient cells, we observed substantially greater inherent sequence instability in APC gene coding sequences compared to reference sequences. Surprisingly, however, this difference was abrogated in MMR defective lines. We also found greater mutation frequency at exonic DNA sequences outwith the APC region in cells defective for either MMR or BER defects. The underlying propensity for mutation at the APC gene is intriguing, while the greater frequency of mutation in cells defective for DNA repair has relevance to understanding events leading to colorectal cancer and other malignancies.
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Affiliation(s)
- Charlotte L Turnbull
- Colon Cancer Genetics Group, Institute of Genetics and Molecular Medicine, University of Edinburgh and MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
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Abstract
Geneticists estimate that 5% to 10% of all cancers diagnosed in the pediatric age range occur in children born with a genetic mutation that directly increases their lifetime risk for neoplasia. However, despite the fact that only a fraction of cancers in children occur as a result of an identified inherited predisposition, characterizing genetic mutations responsible for increased cancer risk in such syndromes has resulted in a profound understanding of relevant molecular pathways involved in carcinogenesis and/or resistance to neoplasia. Importantly, because most cancer predisposition syndromes result in an increased risk of a small number of defined malignancies, personalized prophylactic surveillance and preventive measures can be implemented in affected patients. Lastly, many of the same genetic targets identified from cancer-prone families are mechanistically involved in the majority of sporadic cancers in adults and children, thereby underscoring the clinical relevance of knowledge gained from these defined syndromes and introducing novel therapeutic opportunities to the broader oncologic community. This review highlights the clinical and genetic features of many of the known constitutional genetic syndromes that predispose to malignancy in children and young adults.
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