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Ennour-Idrissi K, Maunsell E, Diorio C. Telomere Length and Breast Cancer Prognosis: A Systematic Review. Cancer Epidemiol Biomarkers Prev 2016; 26:3-10. [PMID: 27677729 DOI: 10.1158/1055-9965.epi-16-0343] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 08/26/2016] [Accepted: 09/16/2016] [Indexed: 01/12/2023] Open
Abstract
Telomeres ensure genome integrity during replication. Loss of telomeric function leads to cell immortalization and accumulation of genetic alterations. The association of telomere length (TL) with breast cancer prognosis is examined through a systematic review. Electronic databases (MEDLINE, EMBASE, CENTRAL), from inception to December 2015, and relevant reviews were searched. Studies that evaluated TL (blood and/or tumor) in association with breast cancer survival or prognostic factor were included. Thirty-six studies met inclusion criteria. Overall risk of bias was critical. Eight studies reported survival outcomes. Overall, there was a trend toward an association of longer telomeres with better outcomes (tumor, not blood). Of the 33 studies reporting associations with prognostic factors, nine adjusted for potential confounders. Among the latter, shorter telomeres were associated with older age (blood, not tumor), higher local recurrence rates (normal tissue), higher tumor grade (tumor), and lower physical activity (blood), which were reported in one study each. TL was not associated with molecular subtype (blood, one study), family history (tumor, one study), chemotherapy (blood, three of four studies), and stress reduction interventions (blood, two of two studies). Although major methodologic differences preclude from drawing conclusive results, TL could be a valuable breast cancer prognostic marker. Cancer Epidemiol Biomarkers Prev; 26(1); 3-10. ©2016 AACR.
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Affiliation(s)
- Kaoutar Ennour-Idrissi
- Axe Oncologie, Centre de Recherche du CHU de Québec-Université Laval, Québec, Canada.,Centre de Recherche sur le Cancer, Université Laval, Québec, Canada.,Département de Médecine Sociale et Préventive, Faculté de Médecine, Université Laval, Québec, Canada
| | - Elizabeth Maunsell
- Axe Oncologie, Centre de Recherche du CHU de Québec-Université Laval, Québec, Canada.,Centre de Recherche sur le Cancer, Université Laval, Québec, Canada.,Département de Médecine Sociale et Préventive, Faculté de Médecine, Université Laval, Québec, Canada.,Centre des Maladies du Sein Deschênes-Fabia, Hôpital du Saint-Sacrement, Québec, Canada
| | - Caroline Diorio
- Axe Oncologie, Centre de Recherche du CHU de Québec-Université Laval, Québec, Canada. .,Centre de Recherche sur le Cancer, Université Laval, Québec, Canada.,Département de Médecine Sociale et Préventive, Faculté de Médecine, Université Laval, Québec, Canada.,Centre des Maladies du Sein Deschênes-Fabia, Hôpital du Saint-Sacrement, Québec, Canada
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Weckselblatt B, Hermetz KE, Rudd MK. Unbalanced translocations arise from diverse mutational mechanisms including chromothripsis. Genome Res 2015; 25:937-47. [PMID: 26070663 PMCID: PMC4484391 DOI: 10.1101/gr.191247.115] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 05/15/2015] [Indexed: 12/17/2022]
Abstract
Unbalanced translocations are a relatively common type of copy number variation and a major contributor to neurodevelopmental disorders. We analyzed the breakpoints of 57 unique unbalanced translocations to investigate the mechanisms of how they form. Fifty-one are simple unbalanced translocations between two different chromosome ends, and six rearrangements have more than three breakpoints involving two to five chromosomes. Sequencing 37 breakpoint junctions revealed that simple translocations have between 0 and 4 base pairs (bp) of microhomology (n = 26), short inserted sequences (n = 8), or paralogous repeats (n = 3) at the junctions, indicating that translocations do not arise primarily from nonallelic homologous recombination but instead form most often via nonhomologous end joining or microhomology-mediated break-induced replication. Three simple translocations fuse genes that are predicted to produce in-frame transcripts of SIRPG-WWOX, SMOC2-PROX1, and PIEZO2-MTA1, which may lead to gain of function. Three complex translocations have inversions, insertions, and multiple breakpoint junctions between only two chromosomes. Whole-genome sequencing and fluorescence in situ hybridization analysis of two de novo translocations revealed at least 18 and 33 breakpoints involving five different chromosomes. Breakpoint sequencing of one maternally inherited translocation involving four chromosomes uncovered multiple breakpoints with inversions and insertions. All of these breakpoint junctions had 0-4 bp of microhomology consistent with chromothripsis, and both de novo events occurred on paternal alleles. Together with other studies, these data suggest that germline chromothripsis arises in the paternal genome and may be transmitted maternally. Breakpoint sequencing of our large collection of chromosome rearrangements provides a comprehensive analysis of the molecular mechanisms behind translocation formation.
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Affiliation(s)
- Brooke Weckselblatt
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Karen E Hermetz
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - M Katharine Rudd
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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Hermetz KE, Newman S, Conneely KN, Martin CL, Ballif BC, Shaffer LG, Cody JD, Rudd MK. Large inverted duplications in the human genome form via a fold-back mechanism. PLoS Genet 2014; 10:e1004139. [PMID: 24497845 PMCID: PMC3907307 DOI: 10.1371/journal.pgen.1004139] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 12/09/2013] [Indexed: 11/27/2022] Open
Abstract
Inverted duplications are a common type of copy number variation (CNV) in germline and somatic genomes. Large duplications that include many genes can lead to both neurodevelopmental phenotypes in children and gene amplifications in tumors. There are several models for inverted duplication formation, most of which include a dicentric chromosome intermediate followed by breakage-fusion-bridge (BFB) cycles, but the mechanisms that give rise to the inverted dicentric chromosome in most inverted duplications remain unknown. Here we have combined high-resolution array CGH, custom sequence capture, next-generation sequencing, and long-range PCR to analyze the breakpoints of 50 nonrecurrent inverted duplications in patients with intellectual disability, autism, and congenital anomalies. For half of the rearrangements in our study, we sequenced at least one breakpoint junction. Sequence analysis of breakpoint junctions reveals a normal-copy disomic spacer between inverted and non-inverted copies of the duplication. Further, short inverted sequences are present at the boundary of the disomic spacer and the inverted duplication. These data support a mechanism of inverted duplication formation whereby a chromosome with a double-strand break intrastrand pairs with itself to form a “fold-back” intermediate that, after DNA replication, produces a dicentric inverted chromosome with a disomic spacer corresponding to the site of the fold-back loop. This process can lead to inverted duplications adjacent to terminal deletions, inverted duplications juxtaposed to translocations, and inverted duplication ring chromosomes. Chromosomes with large inverted duplications and terminal deletions cause neurodevelopmental disorders in children. These chromosome rearrangements typically involve hundreds of genes, leading to significant changes in gene dosage. Though inverted duplications adjacent to terminal deletions are a relatively common type of chromosomal imbalance, the DNA repair mechanism responsible for their formation is not known. In this study, we analyze the genomic organization of the largest collection of human inverted duplications. We find a common inverted duplication structure, consistent with a model that requires DNA to fold back and form a dicentric chromosome intermediate. These data provide insight into the formation of nonrecurrent inverted duplications in the human genome.
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Affiliation(s)
- Karen E Hermetz
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Scott Newman
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Karen N Conneely
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, United States of America ; Department of Biostatistics and Bioinformatics, Emory University School of Public Health, Atlanta, Georgia, United States of America
| | - Christa L Martin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Blake C Ballif
- Signature Genomic Laboratories, PerkinElmer, Inc., Spokane, Washington, United States of America
| | - Lisa G Shaffer
- Signature Genomic Laboratories, PerkinElmer, Inc., Spokane, Washington, United States of America
| | - Jannine D Cody
- Department of Pediatrics, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America ; The Chromosome 18 Registry and Research Society, San Antonio, Texas, United States of America
| | - M Katharine Rudd
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, United States of America
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Mundhofir FEP, Nillesen WM, Van Bon BWM, Smeets D, Pfundt R, van de Ven-Schobers G, Ruiterkamp-Versteeg M, Winarni TI, Hamel BCJ, Yntema HG, Faradz SMH. Subtelomeric chromosomal rearrangements in a large cohort of unexplained intellectually disabled individuals in Indonesia: A clinical and molecular study. INDIAN JOURNAL OF HUMAN GENETICS 2013; 19:171-8. [PMID: 24019618 PMCID: PMC3758723 DOI: 10.4103/0971-6866.116118] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
CONTEXT Unbalanced subtelomeric chromosomal rearrangements are often associated with intellectual disability (ID) and malformation syndromes. The prevalence of such rearrangements has been reported to be 5-9% in ID populations. AIMS To study the prevalence of subtelomeric rearrangements in the Indonesian ID population. MATERIALS AND METHODS We tested 436 subjects with unexplained ID using multiplex ligation dependent probe amplification (MLPA) using the specific designed sets of probes to detect human subtelomeric chromosomal imbalances (SALSA P070 and P036D). If necessary, abnormal findings were confirmed by other MLPA probe kits, fluorescent in situ hybridization or Single Nucleotide Polymorphism array. RESULTS A subtelomeric aberration was identified in 3.7% of patients (16/436). Details on subtelomeric aberrations and confirmation analyses are discussed. CONCLUSION This is the first study describing the presence of subtelomeric rearrangements in individuals with ID in Indonesia. Furthermore, it shows that also in Indonesia such abnormalities are a prime cause of ID and that in developing countries with limited diagnostic services such as Indonesia, it is important and feasible to uncover the genetic etiology in a significant number of cases with ID.
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Affiliation(s)
- Farmaditya E P Mundhofir
- Division of Human Genetics, Center for Biomedical Research, Faculty of Medicine Diponegoro University, Semarang, Indonesia ; Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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