1
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Tolezano GC, Bastos GC, da Costa SS, Freire BL, Homma TK, Honjo RS, Yamamoto GL, Passos-Bueno MR, Koiffmann CP, Kim CA, Vianna-Morgante AM, de Lima Jorge AA, Bertola DR, Rosenberg C, Krepischi ACV. Burden of Rare Copy Number Variants in Microcephaly: A Brazilian Cohort of 185 Microcephalic Patients and Review of the Literature. J Autism Dev Disord 2024; 54:1181-1212. [PMID: 36502452 DOI: 10.1007/s10803-022-05853-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2022] [Indexed: 12/14/2022]
Abstract
Microcephaly presents heterogeneous genetic etiology linked to several neurodevelopmental disorders (NDD). Copy number variants (CNVs) are a causal mechanism of microcephaly whose investigation is a crucial step for unraveling its molecular basis. Our purpose was to investigate the burden of rare CNVs in microcephalic individuals and to review genes and CNV syndromes associated with microcephaly. We performed chromosomal microarray analysis (CMA) in 185 Brazilian patients with microcephaly and evaluated microcephalic patients carrying < 200 kb CNVs documented in the DECIPHER database. Additionally, we reviewed known genes and CNV syndromes causally linked to microcephaly through the PubMed, OMIM, DECIPHER, and ClinGen databases. Rare clinically relevant CNVs were detected in 39 out of the 185 Brazilian patients investigated by CMA (21%). In 31 among the 60 DECIPHER patients carrying < 200 kb CNVs, at least one known microcephaly gene was observed. Overall, four gene sets implicated in microcephaly were disclosed: known microcephaly genes; genes with supporting evidence of association with microcephaly; known macrocephaly genes; and novel candidates, including OTUD7A, BBC3, CNTN6, and NAA15. In the review, we compiled 957 known microcephaly genes and 58 genomic CNV loci, comprising 13 duplications and 50 deletions, which have already been associated with clinical findings including microcephaly. We reviewed genes and CNV syndromes previously associated with microcephaly, reinforced the high CMA diagnostic yield for this condition, pinpointed novel candidate loci linked to microcephaly deserving further evaluation, and provided a useful resource for future research on the field of neurodevelopment.
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Affiliation(s)
- Giovanna Cantini Tolezano
- Department of Genetics and Evolutionary Biology, Human Genome and Stem-Cell Research Center, Institute of Biosciences, University of São Paulo, 106 Rua do Matão, São Paulo, SP, 05508-090, Brazil
| | - Giovanna Civitate Bastos
- Department of Genetics and Evolutionary Biology, Human Genome and Stem-Cell Research Center, Institute of Biosciences, University of São Paulo, 106 Rua do Matão, São Paulo, SP, 05508-090, Brazil
| | - Silvia Souza da Costa
- Department of Genetics and Evolutionary Biology, Human Genome and Stem-Cell Research Center, Institute of Biosciences, University of São Paulo, 106 Rua do Matão, São Paulo, SP, 05508-090, Brazil
| | - Bruna Lucheze Freire
- Unidade de Endocrinologia Genética (LIM25), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, 455 Avenida Doutor Arnaldo, São Paulo, SP, 01246-903, Brazil
| | - Thais Kataoka Homma
- Unidade de Endocrinologia Genética (LIM25), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, 455 Avenida Doutor Arnaldo, São Paulo, SP, 01246-903, Brazil
| | - Rachel Sayuri Honjo
- Unidade de Genética do Instituto da Criança, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, 647 Avenida Doutor Enéas Carvalho de Aguiar, São Paulo, SP, 05403-900, Brazil
| | - Guilherme Lopes Yamamoto
- Department of Genetics and Evolutionary Biology, Human Genome and Stem-Cell Research Center, Institute of Biosciences, University of São Paulo, 106 Rua do Matão, São Paulo, SP, 05508-090, Brazil
- Unidade de Genética do Instituto da Criança, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, 647 Avenida Doutor Enéas Carvalho de Aguiar, São Paulo, SP, 05403-900, Brazil
| | - Maria Rita Passos-Bueno
- Department of Genetics and Evolutionary Biology, Human Genome and Stem-Cell Research Center, Institute of Biosciences, University of São Paulo, 106 Rua do Matão, São Paulo, SP, 05508-090, Brazil
| | - Celia Priszkulnik Koiffmann
- Department of Genetics and Evolutionary Biology, Human Genome and Stem-Cell Research Center, Institute of Biosciences, University of São Paulo, 106 Rua do Matão, São Paulo, SP, 05508-090, Brazil
| | - Chong Ae Kim
- Unidade de Genética do Instituto da Criança, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, 647 Avenida Doutor Enéas Carvalho de Aguiar, São Paulo, SP, 05403-900, Brazil
| | - Angela Maria Vianna-Morgante
- Department of Genetics and Evolutionary Biology, Human Genome and Stem-Cell Research Center, Institute of Biosciences, University of São Paulo, 106 Rua do Matão, São Paulo, SP, 05508-090, Brazil
| | - Alexander Augusto de Lima Jorge
- Unidade de Endocrinologia Genética (LIM25), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, 455 Avenida Doutor Arnaldo, São Paulo, SP, 01246-903, Brazil
| | - Débora Romeo Bertola
- Department of Genetics and Evolutionary Biology, Human Genome and Stem-Cell Research Center, Institute of Biosciences, University of São Paulo, 106 Rua do Matão, São Paulo, SP, 05508-090, Brazil
- Unidade de Genética do Instituto da Criança, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, 647 Avenida Doutor Enéas Carvalho de Aguiar, São Paulo, SP, 05403-900, Brazil
| | - Carla Rosenberg
- Department of Genetics and Evolutionary Biology, Human Genome and Stem-Cell Research Center, Institute of Biosciences, University of São Paulo, 106 Rua do Matão, São Paulo, SP, 05508-090, Brazil
| | - Ana Cristina Victorino Krepischi
- Department of Genetics and Evolutionary Biology, Human Genome and Stem-Cell Research Center, Institute of Biosciences, University of São Paulo, 106 Rua do Matão, São Paulo, SP, 05508-090, Brazil.
- Institute of Biosciences, University of São Paulo, 277 Rua do Matão, São Paulo, SP, 05508-090, Brazil.
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2
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Hughes T, Rose AM. The emergence of Fanconi anaemia type S: a phenotypic spectrum of biallelic BRCA1 mutations. Front Oncol 2023; 13:1278004. [PMID: 38146508 PMCID: PMC10749362 DOI: 10.3389/fonc.2023.1278004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 10/23/2023] [Indexed: 12/27/2023] Open
Abstract
BRCA1 is involved in the Fanconi anaemia (FA) pathway, which coordinates repair of DNA interstrand cross-links. FA is a rare genetic disorder characterised by bone marrow failure, cancer predisposition and congenital abnormalities, caused by biallelic mutations affecting proteins in the FA pathway. Germline monoallelic pathogenic BRCA1 mutations are known to be associated with hereditary breast/ovarian cancer, however biallelic mutations of BRCA1 were long predicted to be incompatible with embryonic viability, hence BRCA1 was not considered to be a canonical FA gene. Despite this, several patients with biallelic pathogenic BRCA1 mutations and FA-like phenotypes have been identified - defining a new FA type (FA-S) and designating BRCA1 as an FA gene. This report presents a scoping review of the cases of biallelic BRCA1 mutations identified to date, discusses the functional effects of the mutations identified, and proposes a phenotypic spectrum of BRCA1 mutations based upon available clinical and genetic data. We report that this FA-S cohort phenotype includes short stature, microcephaly, facial dysmorphisms, hypo/hyperpigmented lesions, intellectual disability, chromosomal sensitivity to crosslinking agents and predisposition to breast/ovarian cancer and/or childhood cancers, with some patients exhibiting sensitivity to chemotherapy. Unlike most other types of FA, FA-S patients lack bone marrow failure.
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Affiliation(s)
- Tirion Hughes
- University of Oxford Medical School, Oxford, United Kingdom
| | - Anna M. Rose
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
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3
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Rawal Y, Jia L, Meir A, Zhou S, Kaur H, Ruben EA, Kwon Y, Bernstein KA, Jasin M, Taylor AB, Burma S, Hromas R, Mazin AV, Zhao W, Zhou D, Wasmuth EV, Greene EC, Sung P, Olsen SK. Structural insights into BCDX2 complex function in homologous recombination. Nature 2023; 619:640-649. [PMID: 37344589 PMCID: PMC10712684 DOI: 10.1038/s41586-023-06219-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 05/15/2023] [Indexed: 06/23/2023]
Abstract
Homologous recombination (HR) fulfils a pivotal role in the repair of DNA double-strand breaks and collapsed replication forks1. HR depends on the products of several paralogues of RAD51, including the tetrameric complex of RAD51B, RAD51C, RAD51D and XRCC2 (BCDX2)2. BCDX2 functions as a mediator of nucleoprotein filament assembly by RAD51 and single-stranded DNA (ssDNA) during HR, but its mechanism remains undefined. Here we report cryogenic electron microscopy reconstructions of human BCDX2 in apo and ssDNA-bound states. The structures reveal how the amino-terminal domains of RAD51B, RAD51C and RAD51D participate in inter-subunit interactions that underpin complex formation and ssDNA-binding specificity. Single-molecule DNA curtain analysis yields insights into how BCDX2 enhances RAD51-ssDNA nucleoprotein filament assembly. Moreover, our cryogenic electron microscopy and functional analyses explain how RAD51C alterations found in patients with cancer3-6 inactivate DNA binding and the HR mediator activity of BCDX2. Our findings shed light on the role of BCDX2 in HR and provide a foundation for understanding how pathogenic alterations in BCDX2 impact genome repair.
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Affiliation(s)
- Yashpal Rawal
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Lijia Jia
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Aviv Meir
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
| | - Shuo Zhou
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Hardeep Kaur
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Eliza A Ruben
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Youngho Kwon
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Kara A Bernstein
- Department of Biochemistry & Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Maria Jasin
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Alexander B Taylor
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Sandeep Burma
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Neurosurgery, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Robert Hromas
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Alexander V Mazin
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Weixing Zhao
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Daohong Zhou
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Elizabeth V Wasmuth
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Eric C Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, USA.
| | - Patrick Sung
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
| | - Shaun K Olsen
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
- Glenn Biggs Institute for Alzheimer's and Neurodegenerative Diseases, San Antonio, TX, USA.
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4
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Zemet R, Du H, Gambin T, Lupski JR, Liu P, Stankiewicz P. SNV/indel hypermutator phenotype in biallelic RAD51C variant: Fanconi anemia. Hum Genet 2023; 142:721-733. [PMID: 37031326 PMCID: PMC10996436 DOI: 10.1007/s00439-023-02550-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 03/24/2023] [Indexed: 04/10/2023]
Abstract
We previously reported a fetus with Fanconi anemia (FA), complementation group O due to compound heterozygous variants involving RAD51C. Interestingly, the trio exome sequencing analysis also detected eight apparent de novo mosaic variants with variant allele fraction (VAF) ranging between 11.5 and 37%. Here, using whole genome sequencing and a 'home-brew' variant filtering pipeline and DeepMosaic module, we investigated the number and signature of de novo heterozygous and mosaic variants and the hypothesis of a rare phenomenon of hypermutation. Eight-hundred-thirty apparent de novo SNVs and 21 de novo indels had VAFs below 37.41% and were considered postzygotic somatic mosaic variants. The VAFs showed a bimodal distribution, with one component having an average VAF of 25% (range: 18.7-37.41%) (n = 446), representing potential postzygotic first mitotic events, and the other component with an average VAF of 12.5% (range 9.55-18.69%) (n = 384), describing potential second mitotic events. No increased rate of CNV formation was observed. The mutational pattern analysis for somatic single base substitution showed SBS40, SBS5, and SBS3 as the top recognized signatures. SBS3 is a known signature associated with homologous recombination-based DNA damage repair error. Our data demonstrate that biallelic RAD51C variants show evidence for defective genomic DNA damage repair and thereby result in a hypermutator phenotype with the accumulation of postzygotic de novo mutations, at least in the prenatal period. This 'genome hypermutator phenomenon' might contribute to the observed hematological manifestations and the predisposition to tumors in patients with FA. We propose that other FA groups should be investigated for genome-wide de novo variants.
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Affiliation(s)
- Roni Zemet
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Haowei Du
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Tomasz Gambin
- Institute of Computer Science, Warsaw University of Technology, Warsaw, Poland
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
| | - Pengfei Liu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
- Baylor Genetics, Houston, TX, USA.
| | - Paweł Stankiewicz
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
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5
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Sanoguera-Miralles L, Valenzuela-Palomo A, Bueno-Martínez E, Llovet P, Díez-Gómez B, Caloca MJ, Pérez-Segura P, Fraile-Bethencourt E, Colmena M, Carvalho S, Allen J, Easton DF, Devilee P, Vreeswijk MPG, de la Hoya M, Velasco EA. Comprehensive Functional Characterization and Clinical Interpretation of 20 Splice-Site Variants of the RAD51C Gene. Cancers (Basel) 2020; 12:E3771. [PMID: 33333735 PMCID: PMC7765170 DOI: 10.3390/cancers12123771] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/08/2020] [Accepted: 12/09/2020] [Indexed: 12/12/2022] Open
Abstract
Hereditary breast and/or ovarian cancer is a highly heterogeneous disease with more than 10 known disease-associated genes. In the framework of the BRIDGES project (Breast Cancer Risk after Diagnostic Gene Sequencing), the RAD51C gene has been sequenced in 60,466 breast cancer patients and 53,461 controls. We aimed at functionally characterizing all the identified genetic variants that are predicted to disrupt the splicing process. Forty RAD51C variants of the intron-exon boundaries were bioinformatically analyzed, 20 of which were selected for splicing functional assays. To test them, a splicing reporter minigene with exons 2 to 8 was designed and constructed. This minigene generated a full-length transcript of the expected size (1062 nucleotides), sequence, and structure (Vector exon V1- RAD51C exons_2-8- Vector exon V2). The 20 candidate variants were genetically engineered into the wild type minigene and functionally assayed in MCF-7 cells. Nineteen variants (95%) impaired splicing, while 18 of them produced severe splicing anomalies. At least 35 transcripts were generated by the mutant minigenes: 16 protein-truncating, 6 in-frame, and 13 minor uncharacterized isoforms. According to ACMG/AMP-based standards, 15 variants could be classified as pathogenic or likely pathogenic variants: c.404G > A, c.405-6T > A, c.571 + 4A > G, c.571 + 5G > A, c.572-1G > T, c.705G > T, c.706-2A > C, c.706-2A > G, c.837 + 2T > C, c.905-3C > G, c.905-2A > C, c.905-2_905-1del, c.965 + 5G > A, c.1026 + 5_1026 + 7del, and c.1026 + 5G > T.
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Affiliation(s)
- Lara Sanoguera-Miralles
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (L.S.-M.); (A.V.-P.); (E.B.-M.); (B.D.-G.); (E.F.-B.)
| | - Alberto Valenzuela-Palomo
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (L.S.-M.); (A.V.-P.); (E.B.-M.); (B.D.-G.); (E.F.-B.)
| | - Elena Bueno-Martínez
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (L.S.-M.); (A.V.-P.); (E.B.-M.); (B.D.-G.); (E.F.-B.)
| | - Patricia Llovet
- Molecular Oncology Laboratory CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), 28040 Madrid, Spain; (P.L.); (P.P.-S.); (M.C.)
| | - Beatriz Díez-Gómez
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (L.S.-M.); (A.V.-P.); (E.B.-M.); (B.D.-G.); (E.F.-B.)
| | - María José Caloca
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain;
| | - Pedro Pérez-Segura
- Molecular Oncology Laboratory CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), 28040 Madrid, Spain; (P.L.); (P.P.-S.); (M.C.)
| | - Eugenia Fraile-Bethencourt
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (L.S.-M.); (A.V.-P.); (E.B.-M.); (B.D.-G.); (E.F.-B.)
- Knight Cancer Research Building, 2720 S Moody Ave, Portland, OR 97201, USA
| | - Marta Colmena
- Molecular Oncology Laboratory CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), 28040 Madrid, Spain; (P.L.); (P.P.-S.); (M.C.)
| | - Sara Carvalho
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, University of Cambridge, Cambridge CB1 8RN, UK; (S.C.); (J.A.); (D.F.E.)
| | - Jamie Allen
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, University of Cambridge, Cambridge CB1 8RN, UK; (S.C.); (J.A.); (D.F.E.)
| | - Douglas F. Easton
- Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, University of Cambridge, Cambridge CB1 8RN, UK; (S.C.); (J.A.); (D.F.E.)
| | - Peter Devilee
- Leiden University Medical Center, Department of Human Genetics, 2300RC Leiden, The Netherlands; (P.D.); (M.P.G.V.)
| | - Maaike P. G. Vreeswijk
- Leiden University Medical Center, Department of Human Genetics, 2300RC Leiden, The Netherlands; (P.D.); (M.P.G.V.)
| | - Miguel de la Hoya
- Molecular Oncology Laboratory CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), 28040 Madrid, Spain; (P.L.); (P.P.-S.); (M.C.)
| | - Eladio A. Velasco
- Splicing and Genetic Susceptibility to Cancer, Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC-UVa), 47003 Valladolid, Spain; (L.S.-M.); (A.V.-P.); (E.B.-M.); (B.D.-G.); (E.F.-B.)
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6
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Dawson LM, Smith KN, Werdyani S, Ndikumana R, Penney C, Wiede LL, Smith KL, Pater JA, MacMillan A, Green J, Drover S, Young TL, O'Rielly DD. A dominant RAD51C pathogenic splicing variant predisposes to breast and ovarian cancer in the Newfoundland population due to founder effect. Mol Genet Genomic Med 2019; 8:e1070. [PMID: 31782267 PMCID: PMC7005661 DOI: 10.1002/mgg3.1070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 11/01/2019] [Accepted: 11/11/2019] [Indexed: 12/20/2022] Open
Abstract
Background RAD51C is important in DNA repair and individuals with pathogenic RAD51C variants have increased risk of hereditary breast and ovarian cancer syndrome (HBOC), an autosomal dominant genetic predisposition to early onset breast and/or ovarian cancer. Methods Five female HBOC probands sequenced negative for moderate‐ and high‐risk genes but shared a recurrent variant of uncertain significance in RAD51C (NM_058216.3: c.571 + 4A > G). Participant recruitment was followed by haplotype and case/control analyses, RNA splicing analysis, gene and protein expression assays, and Sanger sequencing of tumors. Results The RAD51C c.571 + 4A > G variant segregates with HBOC, with heterozygotes sharing a 5.07 Mbp haplotype. RAD51C c.571 + 4A > G is increased ~52‐fold in the Newfoundland population compared with the general Caucasian population and positive population controls share disease‐associated alleles, providing evidence of a founder effect. Splicing analysis confirmed in silico predictions that RAD51C c.571 + 4A > G causes exon 3 skipping, creating an immediate premature termination codon. Gene and protein expression were significantly reduced in a RAD51C c.571 + 4G > A heterozygote compared with a wild‐type relative. Sanger sequencing of tumors from two probands indicates loss‐of‐heterozygosity, suggesting loss of function. Conclusion The RAD51C c.571 + 4A > G variant affects mRNA splicing and should be re‐classified as pathogenic according to American College of Medical Genetics and Genomics guidelines.
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Affiliation(s)
- Lesa M Dawson
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada.,Eastern Health Authority, St. John's, NL, Canada
| | - Kerri N Smith
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Salem Werdyani
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Robyn Ndikumana
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Cindy Penney
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Louisa L Wiede
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Kendra L Smith
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Justin A Pater
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | | | - Jane Green
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Sheila Drover
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Terry-Lynn Young
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada.,Eastern Health Authority, St. John's, NL, Canada.,Centre for Translational Genomics, St. John's, NL, Canada
| | - Darren D O'Rielly
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada.,Eastern Health Authority, St. John's, NL, Canada.,Centre for Translational Genomics, St. John's, NL, Canada
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7
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Cao Y, Tokita MJ, Chen ES, Ghosh R, Chen T, Feng Y, Gorman E, Gibellini F, Ward PA, Braxton A, Wang X, Meng L, Xiao R, Bi W, Xia F, Eng CM, Yang Y, Gambin T, Shaw C, Liu P, Stankiewicz P. A clinical survey of mosaic single nucleotide variants in disease-causing genes detected by exome sequencing. Genome Med 2019; 11:48. [PMID: 31349857 PMCID: PMC6660700 DOI: 10.1186/s13073-019-0658-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 07/11/2019] [Indexed: 12/23/2022] Open
Abstract
Background Although mosaic variation has been known to cause disease for decades, high-throughput sequencing technologies with the analytical sensitivity to consistently detect variants at reduced allelic fractions have only recently emerged as routine clinical diagnostic tests. To date, few systematic analyses of mosaic variants detected by diagnostic exome sequencing for diverse clinical indications have been performed. Methods To investigate the frequency, type, allelic fraction, and phenotypic consequences of clinically relevant somatic mosaic single nucleotide variants (SNVs) and characteristics of the corresponding genes, we retrospectively queried reported mosaic variants from a cohort of ~ 12,000 samples submitted for clinical exome sequencing (ES) at Baylor Genetics. Results We found 120 mosaic variants involving 107 genes, including 80 mosaic SNVs in proband samples and 40 in parental/grandparental samples. Average mosaic alternate allele fraction (AAF) detected in autosomes and in X-linked disease genes in females was 18.2% compared with 34.8% in X-linked disease genes in males. Of these mosaic variants, 74 variants (61.7%) were classified as pathogenic or likely pathogenic and 46 (38.3%) as variants of uncertain significance. Mosaic variants occurred in disease genes associated with autosomal dominant (AD) or AD/autosomal recessive (AR) (67/120, 55.8%), X-linked (33/120, 27.5%), AD/somatic (10/120, 8.3%), and AR (8/120, 6.7%) inheritance. Of note, 1.7% (2/120) of variants were found in genes in which only somatic events have been described. Nine genes had recurrent mosaic events in unrelated individuals which accounted for 18.3% (22/120) of all detected mosaic variants in this study. The proband group was enriched for mosaicism affecting Ras signaling pathway genes. Conclusions In sum, an estimated 1.5% of all molecular diagnoses made in this cohort could be attributed to a mosaic variant detected in the proband, while parental mosaicism was identified in 0.3% of families analyzed. As ES design favors breadth over depth of coverage, this estimate of the prevalence of mosaic variants likely represents an underestimate of the total number of clinically relevant mosaic variants in our cohort. Electronic supplementary material The online version of this article (10.1186/s13073-019-0658-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ye Cao
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA.,Baylor Genetics, Houston, TX, USA.,Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Mari J Tokita
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA
| | - Edward S Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA
| | - Rajarshi Ghosh
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA.,Baylor Genetics, Houston, TX, USA
| | | | | | | | | | - Patricia A Ward
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA.,Baylor Genetics, Houston, TX, USA
| | | | - Xia Wang
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA.,Baylor Genetics, Houston, TX, USA
| | - Linyan Meng
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA.,Baylor Genetics, Houston, TX, USA
| | - Rui Xiao
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA.,Baylor Genetics, Houston, TX, USA
| | - Weimin Bi
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA.,Baylor Genetics, Houston, TX, USA
| | - Fan Xia
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA.,Baylor Genetics, Houston, TX, USA
| | - Christine M Eng
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA.,Baylor Genetics, Houston, TX, USA
| | - Yaping Yang
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA.,Baylor Genetics, Houston, TX, USA
| | - Tomasz Gambin
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA.,Department of Medical Genetics, Institute of Mother and Child, Warsaw, Poland.,Institute of Computer Science, Warsaw University of Technology, Warsaw, Poland
| | - Chad Shaw
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA.,Department of Statistics, Rice University, Houston, TX, USA
| | - Pengfei Liu
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA. .,Baylor Genetics, Houston, TX, USA.
| | - Pawel Stankiewicz
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030-3411, USA. .,Baylor Genetics, Houston, TX, USA.
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Goyal A, Gaddis K, Bohjanen K. Multifocal paraganglioma, mycosis fungoides, and monoclonal B-cell lymphocytosis in association with RAD51C mutation. JAAD Case Rep 2019; 5:240-241. [PMID: 30847381 PMCID: PMC6389551 DOI: 10.1016/j.jdcr.2019.01.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Amrita Goyal
- Department of Dermatology, University of Minnesota, Minneapolis, MN
| | - Kevin Gaddis
- Department of Dermatology, University of Minnesota, Minneapolis, MN
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9
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RAD-ical New Insights into RAD51 Regulation. Genes (Basel) 2018; 9:genes9120629. [PMID: 30551670 PMCID: PMC6316741 DOI: 10.3390/genes9120629] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 12/04/2018] [Accepted: 12/07/2018] [Indexed: 01/17/2023] Open
Abstract
The accurate repair of DNA is critical for genome stability and cancer prevention. DNA double-strand breaks are one of the most toxic lesions; however, they can be repaired using homologous recombination. Homologous recombination is a high-fidelity DNA repair pathway that uses a homologous template for repair. One central HR step is RAD51 nucleoprotein filament formation on the single-stranded DNA ends, which is a step required for the homology search and strand invasion steps of HR. RAD51 filament formation is tightly controlled by many positive and negative regulators, which are collectively termed the RAD51 mediators. The RAD51 mediators function to nucleate, elongate, stabilize, and disassemble RAD51 during repair. In model organisms, RAD51 paralogs are RAD51 mediator proteins that structurally resemble RAD51 and promote its HR activity. New functions for the RAD51 paralogs during replication and in RAD51 filament flexibility have recently been uncovered. Mutations in the human RAD51 paralogs (RAD51B, RAD51C, RAD51D, XRCC2, XRCC3, and SWSAP1) are found in a subset of breast and ovarian cancers. Despite their discovery three decades ago, few advances have been made in understanding the function of the human RAD51 paralogs. Here, we discuss the current perspective on the in vivo and in vitro function of the RAD51 paralogs, and their relationship with cancer in vertebrate models.
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