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Esposito S, Zollo I, Villella VR, Scialò F, Giordano S, Esposito MV, Salemme N, Di Domenico C, Cernera G, Zarrilli F, Castaldo G, Amato F. Identification of an ultra-rare Alu insertion in the CFTR gene: Pitfalls and challenges in genetic test interpretation. Clin Chim Acta 2024; 558:118317. [PMID: 38580140 DOI: 10.1016/j.cca.2024.118317] [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: 03/14/2024] [Revised: 03/28/2024] [Accepted: 04/03/2024] [Indexed: 04/07/2024]
Abstract
Cystic fibrosis (CF) is a life-limiting genetic disorder characterized by defective chloride ion transport due to mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Early detection through newborn screening programs significantly improves outcomes for individuals with CF by enabling timely intervention. Here, we report the identification of an Alu element insertion within the exon 15 of CFTR gene, initially overlooked in standard next-generation sequencing analyses. However, using traditional molecular techniques, based on polymerase chain reaction and Sanger sequencing, allowed the identification of the Alu element and the reporting of a correct diagnosis. Our analysis, based on bioinformatics tools and molecular techniques, revealed that the Alu element insertion severely affects the gene expression, splicing patterns, and structure of CFTR protein. In conclusion, this study emphasizes the importance of how the integration of human expertise and modern technologies represents a pivotal step forward in genomic medicine, ensuring the delivery of precision healthcare to individuals affected by genetic diseases.
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Affiliation(s)
- Speranza Esposito
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy; CEINGE- Advanced Biotechnologies Franco Salvatore, Naples, Italy
| | - Immacolata Zollo
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy; CEINGE- Advanced Biotechnologies Franco Salvatore, Naples, Italy
| | - Valeria Rachela Villella
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy; CEINGE- Advanced Biotechnologies Franco Salvatore, Naples, Italy
| | - Filippo Scialò
- CEINGE- Advanced Biotechnologies Franco Salvatore, Naples, Italy; Department of Translational Medical Science, University of Campania Luigi Vanvitelli, Naples, Italy
| | - Sonia Giordano
- AORN Ospedali dei Colli-Monaldi-Cotugno-CTO, Naples, Italy
| | | | - Nunzia Salemme
- San Giuseppe and Melorio Hospital, Santa Maria Capua Vetere, Caserta, Italy
| | | | - Gustavo Cernera
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy; CEINGE- Advanced Biotechnologies Franco Salvatore, Naples, Italy
| | - Federica Zarrilli
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy; CEINGE- Advanced Biotechnologies Franco Salvatore, Naples, Italy
| | - Giuseppe Castaldo
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy; CEINGE- Advanced Biotechnologies Franco Salvatore, Naples, Italy
| | - Felice Amato
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy; CEINGE- Advanced Biotechnologies Franco Salvatore, Naples, Italy.
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2
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Moore AR, Yu J, Pei Y, Cheng EWY, Taylor Tavares AL, Walker WT, Thomas NS, Kamath A, Ibitoye R, Josifova D, Wilsdon A, Ross A, Calder AD, Offiah AC, Wilkie AOM, Taylor JC, Pagnamenta AT. Use of genome sequencing to hunt for cryptic second-hit variants: analysis of 31 cases recruited to the 100 000 Genomes Project. J Med Genet 2023; 60:1235-1244. [PMID: 37558402 PMCID: PMC10715503 DOI: 10.1136/jmg-2023-109362] [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: 04/26/2023] [Accepted: 07/28/2023] [Indexed: 08/11/2023]
Abstract
BACKGROUND Current clinical testing methods used to uncover the genetic basis of rare disease have inherent limitations, which can lead to causative pathogenic variants being missed. Within the rare disease arm of the 100 000 Genomes Project (100kGP), families were recruited under the clinical indication 'single autosomal recessive mutation in rare disease'. These participants presented with strong clinical suspicion for a specific autosomal recessive disorder, but only one suspected pathogenic variant had been identified through standard-of-care testing. Whole genome sequencing (WGS) aimed to identify cryptic 'second-hit' variants. METHODS To investigate the 31 families with available data that remained unsolved following formal review within the 100kGP, SVRare was used to aggregate structural variants present in <1% of 100kGP participants. Small variants were assessed using population allele frequency data and SpliceAI. Literature searches and publicly available online tools were used for further annotation of pathogenicity. RESULTS Using these strategies, 8/31 cases were solved, increasing the overall diagnostic yield of this cohort from 10/41 (24.4%) to 18/41 (43.9%). Exemplar cases include a patient with cystic fibrosis harbouring a novel exonic LINE1 insertion in CFTR and a patient with generalised arterial calcification of infancy with complex interlinked duplications involving exons 2-6 of ENPP1. Although ambiguous by short-read WGS, the ENPP1 variant structure was resolved using optical genome mapping and RNA analysis. CONCLUSION Systematic examination of cryptic variants across a multi-disease cohort successfully identifies additional pathogenic variants. WGS data analysis in autosomal recessive rare disease should consider complex structural and small intronic variants as potentially pathogenic second hits.
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Affiliation(s)
- A Rachel Moore
- Wellcome Centre for Human Genetics, NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
- Cambridge Genomics Laboratory, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Jing Yu
- Wellcome Centre for Human Genetics, NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Yang Pei
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | | | | | - Woolf T Walker
- School of Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
- PCD Centre, University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - N Simon Thomas
- Wessex Regional Genetics Laboratory, Salisbury NHS Foundation Trust, Salisbury, UK
| | - Arveen Kamath
- All Wales Medical Genomics Service, University Hospital of Wales, Cardiff, UK
| | - Rita Ibitoye
- North West Thames Regional Genetics Service, Northwick Park Hospital, Harrow, London, UK
| | - Dragana Josifova
- Department of Clinical Genetics, Guy's and St Thomas' Hospitals NHS Trust, London, UK
| | - Anna Wilsdon
- Clinical Genetics, Nottingham City Hospital, Nottingham, UK
| | - Alison Ross
- Clinical Genetics, NHS Grampian, Aberdeen, UK
| | - Alistair D Calder
- Radiology Department, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Amaka C Offiah
- Department of Oncology and Metabolism, The University of Sheffield, Sheffield, UK
| | - Andrew O M Wilkie
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Jenny C Taylor
- Wellcome Centre for Human Genetics, NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
| | - Alistair T Pagnamenta
- Wellcome Centre for Human Genetics, NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
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3
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Kosushkin SA, Ustyantsev IG, Borodulina OR, Vassetzky NS, Kramerov DA. Tail Wags Dog’s SINE: Retropositional Mechanisms of Can SINE Depend on Its A-Tail Structure. BIOLOGY 2022; 11:biology11101403. [PMID: 36290307 PMCID: PMC9599045 DOI: 10.3390/biology11101403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 09/17/2022] [Accepted: 09/22/2022] [Indexed: 11/25/2022]
Abstract
Simple Summary The genomes of higher organisms including humans are invaded by millions of repetitive elements (transposons), which can sometimes be deleterious or beneficial for hosts. Many aspects of the mechanisms underlying the expansion of transposons in the genomes remain unclear. Short retrotransposons (SINEs) are one of the most abundant classes of genomic repeats. Their amplification relies on two major processes: transcription and reverse transcription. Here, short retrotransposons of dogs and other canids called Can SINE were analyzed. Their amplification was extraordinarily active in the wolf and, particularly, dog breeds relative to other canids. We also studied a variation of their transcription mechanism involving the polyadenylation of transcripts. An analysis of specific signals involved in this process allowed us to conclude that Can SINEs could alternate amplification with and without polyadenylation in their evolution. Understanding the mechanisms of transposon replication can shed light on the mechanisms of genome function. Abstract SINEs, non-autonomous short retrotransposons, are widespread in mammalian genomes. Their transcripts are generated by RNA polymerase III (pol III). Transcripts of certain SINEs can be polyadenylated, which requires polyadenylation and pol III termination signals in their sequences. Our sequence analysis divided Can SINEs in canids into four subfamilies, older a1 and a2 and younger b1 and b2. Can_b2 and to a lesser extent Can_b1 remained retrotranspositionally active, while the amplification of Can_a1 and Can_a2 ceased long ago. An extraordinarily high Can amplification was revealed in different dog breeds. Functional polyadenylation signals were analyzed in Can subfamilies, particularly in fractions of recently amplified, i.e., active copies. The transcription of various Can constructs transfected into HeLa cells proposed AATAAA and (TC)n as functional polyadenylation signals. Our analysis indicates that older Can subfamilies (a1, a2, and b1) with an active transcription terminator were amplified by the T+ mechanism (with polyadenylation of pol III transcripts). In the currently active Can_b2 subfamily, the amplification mechanisms with (T+) and without the polyadenylation of pol III transcripts (T−) irregularly alternate. The active transcription terminator tends to shorten, which renders it nonfunctional and favors a switch to the T− retrotransposition. The activity of a truncated terminator is occasionally restored by its elongation, which rehabilitates the T+ retrotransposition for a particular SINE copy.
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4
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Teresi SJ, Teresi MB, Edger PP. TE Density: a tool to investigate the biology of transposable elements. Mob DNA 2022; 13:11. [PMID: 35413944 PMCID: PMC9004194 DOI: 10.1186/s13100-022-00264-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 02/16/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Transposable elements (TEs) are powerful creators of genotypic and phenotypic diversity due to their inherent mutagenic capabilities and in this way they serve as a deep reservoir of sequences for genomic variation. As agents of genetic disruption, a TE's potential to impact phenotype is partially a factor of its location in the genome. Previous research has shown TEs' ability to impact the expression of neighboring genes, however our understanding of this trend is hampered by the exceptional amount of diversity in the TE world, and a lack of publicly available computational methods that quantify the presence of TEs relative to genes. RESULTS Here, we have developed a tool to more easily quantify TE presence relative to genes through the use of only a gene and TE annotation, yielding a new metric we call TE Density. Briefly defined as the proportion of TE-occupied base-pairs relative to a window-size of the genome. This new pipeline reports TE density for each gene in the genome, for each type descriptor of TE (order and superfamily), and for multiple positions and distances relative to the gene (upstream, intragenic, and downstream) over sliding, user-defined windows. In this way, we overcome previous limitations to the study of TE-gene relationships by focusing on all TE types present in the genome, utilizing flexible genomic distances for measurement, and reporting a TE presence metric for every gene in the genome. CONCLUSIONS Together, this new tool opens up new avenues for studying TE-gene relationships, genome architecture, comparative genomics, and the tremendous diversity present of the TE world. TE Density is open-source and freely available at: https://github.com/sjteresi/TE_Density .
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Affiliation(s)
- Scott J Teresi
- Department of Horticulture, Michigan State University, East Lansing, Michigan, USA
- Genetics and Genome Sciences Program, Michigan State University, East Lansing, Michigan, USA
| | | | - Patrick P Edger
- Department of Horticulture, Michigan State University, East Lansing, Michigan, USA.
- Genetics and Genome Sciences Program, Michigan State University, East Lansing, Michigan, USA.
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5
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Expression Quantitative Trait Loci (eQTLs) Associated with Retrotransposons Demonstrate their Modulatory Effect on the Transcriptome. Int J Mol Sci 2021; 22:ijms22126319. [PMID: 34204806 PMCID: PMC8231655 DOI: 10.3390/ijms22126319] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 06/03/2021] [Accepted: 06/10/2021] [Indexed: 12/26/2022] Open
Abstract
Transposable elements (TEs) are repetitive elements that belong to a variety of functional classes and have an important role in shaping genome evolution. Around 50% of the human genome contains TEs, and they have been termed the "dark matter" of the genome because relatively little is known about their function. While TEs have been shown to participate in aberrant gene regulation and the pathogenesis of diseases, only a few studies have explored the systemic effect of TEs on gene expression. In the present study, we analysed whole genome sequences and blood whole transcriptome data from 570 individuals within the Parkinson's Progressive Markers Initiative (PPMI) cohort to identify expression quantitative trait loci (eQTL) regulating genome-wide gene expression associated with TEs. We identified 2132 reference TEs that were polymorphic for their presence or absence in our study cohort. The presence or absence of the TE element could change the expression of the gene or gene clusters from zero to tens of thousands of copies of RNA. The main finding is that many TEs possess very strong regulatory effects, and they have the potential to modulate large genetic networks with hundreds of target genes over the genome. We illustrate the plethora of regulatory mechanisms using examples of their action at the HLA gene cluster and data showing different TEs' convergence to modulate WFS1 gene expression. In conclusion, the presence or absence of polymorphisms of TEs has an eminent genome-wide regulatory function with large effect size at the level of the whole transcriptome. The role of TEs in explaining, in part, the missing heritability for complex traits is convincing and should be considered.
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6
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Jain D, Chu C, Alver BH, Lee S, Lee EA, Park PJ. HiTea: a computational pipeline to identify non-reference transposable element insertions in Hi-C data. Bioinformatics 2021; 37:1045-1051. [PMID: 33136153 DOI: 10.1093/bioinformatics/btaa923] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 09/14/2020] [Accepted: 10/17/2020] [Indexed: 11/13/2022] Open
Abstract
Hi-C is a common technique for assessing 3D chromatin conformation. Recent studies have shown that long-range interaction information in Hi-C data can be used to generate chromosome-length genome assemblies and identify large-scale structural variations. Here, we demonstrate the use of Hi-C data in detecting mobile transposable element (TE) insertions genome-wide. Our pipeline Hi-C-based TE analyzer (HiTea) capitalizes on clipped Hi-C reads and is aided by a high proportion of discordant read pairs in Hi-C data to detect insertions of three major families of active human TEs. Despite the uneven genome coverage in Hi-C data, HiTea is competitive with the existing callers based on whole-genome sequencing (WGS) data and can supplement the WGS-based characterization of the TE-insertion landscape. We employ the pipeline to identify TE-insertions from human cell-line Hi-C samples. AVAILABILITY AND IMPLEMENTATION HiTea is available at https://github.com/parklab/HiTea and as a Docker image. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Dhawal Jain
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Chong Chu
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Burak Han Alver
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Soohyun Lee
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Eunjung Alice Lee
- Division of Genetics and Genomics, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.,Broad Institute of MIT and Harvard University, Cambridge, MA 02142, USA
| | - Peter J Park
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
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7
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Emamalipour M, Seidi K, Zununi Vahed S, Jahanban-Esfahlan A, Jaymand M, Majdi H, Amoozgar Z, Chitkushev LT, Javaheri T, Jahanban-Esfahlan R, Zare P. Horizontal Gene Transfer: From Evolutionary Flexibility to Disease Progression. Front Cell Dev Biol 2020; 8:229. [PMID: 32509768 PMCID: PMC7248198 DOI: 10.3389/fcell.2020.00229] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 03/17/2020] [Indexed: 12/11/2022] Open
Abstract
Flexibility in the exchange of genetic material takes place between different organisms of the same or different species. This phenomenon is known to play a key role in the genetic, physiological, and ecological performance of the host. Exchange of genetic materials can cause both beneficial and/or adverse biological consequences. Horizontal gene transfer (HGT) or lateral gene transfer (LGT) as a general mechanism leads to biodiversity and biological innovations in nature. HGT mediators are one of the genetic engineering tools used for selective introduction of desired changes in the genome for gene/cell therapy purposes. HGT, however, is crucial in development, emergence, and recurrence of various human-related diseases, such as cancer, genetic-, metabolic-, and neurodegenerative disorders and can negatively affect the therapeutic outcome by promoting resistant forms or disrupting the performance of genome editing toolkits. Because of the importance of HGT and its vital physio- and pathological roles, here the variety of HGT mechanisms are reviewed, ranging from extracellular vesicles (EVs) and nanotubes in prokaryotes to cell-free DNA and apoptotic bodies in eukaryotes. Next, we argue that HGT plays a role both in the development of useful features and in pathological states associated with emerging and recurrent forms of the disease. A better understanding of the different HGT mediators and their genome-altering effects/potentials may pave the way for the development of more effective therapeutic and diagnostic regimes.
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Affiliation(s)
- Melissa Emamalipour
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Khaled Seidi
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | | | - Mehdi Jaymand
- Nano Drug Delivery Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Hasan Majdi
- Department of Medical Nanotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Zohreh Amoozgar
- Edwin L. Steele Laboratories, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - L T Chitkushev
- Department of Computer Science, Metropolitan College, Boston University, Boston, MA, United States.,Health Informatics Lab, Metropolitan College, Boston University, Boston, MA, United States
| | - Tahereh Javaheri
- Health Informatics Lab, Metropolitan College, Boston University, Boston, MA, United States
| | - Rana Jahanban-Esfahlan
- Department of Medical Biotechnology, School of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Peyman Zare
- Faculty of Medicine, Cardinal Stefan Wyszyński University in Warsaw, Warsaw, Poland.,Dioscuri Center of Chromatin Biology and Epigenomics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
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8
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Petrova G, Yaneva N, Hrbková J, Libik M, Savov A, Macek M. Identification of 99% of CFTR gene mutations in Bulgarian-, Bulgarian Turk-, and Roma cystic fibrosis patients. Mol Genet Genomic Med 2019; 7:e696. [PMID: 31245908 PMCID: PMC6687650 DOI: 10.1002/mgg3.696] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 03/30/2019] [Accepted: 04/07/2019] [Indexed: 01/25/2023] Open
Abstract
Background The spectrum and frequencies of CFTR mutations causing Cystic fibrosis (CF) varies among different populations in Europe, and beyond. Methods We identified 98.9% of all CFTR mutations in a representative cohort of 140 CF patients comprising 107 Bulgarian‐ (BG), 17 BG Turk‐, and 16 BG Roma cases. The compiled clinical and genotype dataset includes 110 previously analyzed patients with 30 cases currently analyzed for rare CFTR variants by massively parallel sequencing of the entire CFTR coding region and adjacent introns combined with the analysis of intra‐CFTR rearrangements. Results Altogether 53 different mutations, of which 15 newly identified in the BG CF population, were observed. Comparison of clinical and laboratory data between individual BG ethnic groups proved that BG Roma have a more severe nutritional status and are younger than other CF patients, as well as that the spectrum mutations differs between them. Conclusion This collaborative study improves genetic counselling in BG, facilitates introduction of multitier CF neonatal screening and fosters public health measures for improvement of care in the Roma CF population.
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Affiliation(s)
- Guergana Petrova
- Pediatric Clinic, University Hospital Alexandrovska, Sofia, Bulgaria.,Pediatric Department, Medical University Sofia, Sofia, Bulgaria
| | - Nadezhda Yaneva
- University Specialized Hospital for Active Treatment in Obstetrics and Gynecology, 'Maichin dom', National Genetic Laboratory, Sofia, Bulgaria.,Medical University Sofia, Sofia, Bulgaria
| | - Jana Hrbková
- Department of Biology and Medical Genetics, University Hospital Motol, Prague, Czech Republic.,Faculty of Medicine of Charles University, Prague, Czech Republic
| | - Malgorzata Libik
- Department of Biology and Medical Genetics, University Hospital Motol, Prague, Czech Republic.,Faculty of Medicine of Charles University, Prague, Czech Republic
| | - Alexey Savov
- University Specialized Hospital for Active Treatment in Obstetrics and Gynecology, 'Maichin dom', National Genetic Laboratory, Sofia, Bulgaria.,Medical University Sofia, Sofia, Bulgaria
| | - Milan Macek
- Department of Biology and Medical Genetics, University Hospital Motol, Prague, Czech Republic.,Faculty of Medicine of Charles University, Prague, Czech Republic
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9
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Schumann GG, Fuchs NV, Tristán-Ramos P, Sebe A, Ivics Z, Heras SR. The impact of transposable element activity on therapeutically relevant human stem cells. Mob DNA 2019; 10:9. [PMID: 30899334 PMCID: PMC6408843 DOI: 10.1186/s13100-019-0151-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 02/27/2019] [Indexed: 12/11/2022] Open
Abstract
Human stem cells harbor significant potential for basic and clinical translational research as well as regenerative medicine. Currently ~ 3000 adult and ~ 30 pluripotent stem cell-based, interventional clinical trials are ongoing worldwide, and numbers are increasing continuously. Although stem cells are promising cell sources to treat a wide range of human diseases, there are also concerns regarding potential risks associated with their clinical use, including genomic instability and tumorigenesis concerns. Thus, a deeper understanding of the factors and molecular mechanisms contributing to stem cell genome stability are a prerequisite to harnessing their therapeutic potential for degenerative diseases. Chemical and physical factors are known to influence the stability of stem cell genomes, together with random mutations and Copy Number Variants (CNVs) that accumulated in cultured human stem cells. Here we review the activity of endogenous transposable elements (TEs) in human multipotent and pluripotent stem cells, and the consequences of their mobility for genomic integrity and host gene expression. We describe transcriptional and post-transcriptional mechanisms antagonizing the spread of TEs in the human genome, and highlight those that are more prevalent in multipotent and pluripotent stem cells. Notably, TEs do not only represent a source of mutations/CNVs in genomes, but are also often harnessed as tools to engineer the stem cell genome; thus, we also describe and discuss the most widely applied transposon-based tools and highlight the most relevant areas of their biomedical applications in stem cells. Taken together, this review will contribute to the assessment of the risk that endogenous TE activity and the application of genetically engineered TEs constitute for the biosafety of stem cells to be used for substitutive and regenerative cell therapies.
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Affiliation(s)
- Gerald G Schumann
- 1Division of Medical Biotechnology, Paul-Ehrlich-Institut, Paul-Ehrlich-Str.51-59, 63225 Langen, Germany
| | - Nina V Fuchs
- 2Host-Pathogen Interactions, Paul-Ehrlich-Institut, Paul-Ehrlich-Str. 51-59, 63225 Langen, Germany
| | - Pablo Tristán-Ramos
- 3GENYO. Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, PTS Granada-Avenida de la Ilustración, 114, 18016 Granada, Spain.,4Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071 Granada, Spain
| | - Attila Sebe
- 1Division of Medical Biotechnology, Paul-Ehrlich-Institut, Paul-Ehrlich-Str.51-59, 63225 Langen, Germany
| | - Zoltán Ivics
- 1Division of Medical Biotechnology, Paul-Ehrlich-Institut, Paul-Ehrlich-Str.51-59, 63225 Langen, Germany
| | - Sara R Heras
- 3GENYO. Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, PTS Granada-Avenida de la Ilustración, 114, 18016 Granada, Spain.,4Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071 Granada, Spain
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10
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Ferguson LB, Zhang L, Wang S, Bridges C, Harris RA, Ponomarev I. Peroxisome Proliferator Activated Receptor Agonists Modulate Transposable Element Expression in Brain and Liver. Front Mol Neurosci 2018; 11:331. [PMID: 30283300 PMCID: PMC6156381 DOI: 10.3389/fnmol.2018.00331] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 08/27/2018] [Indexed: 12/17/2022] Open
Abstract
Peroxisome proliferator activated receptors (PPARs) are nuclear hormone receptors that act as transcription factors in response to endogenous lipid messengers. The fibrates and thiazolidinediones are synthetic PPAR agonists used clinically to treat dyslipidemia and Type 2 Diabetes Mellitus, respectively, but also improve symptoms of several other diseases. Transposable elements (TEs), repetitive sequences in mammalian genomes, are implicated in many of the same conditions for which PPAR agonists are therapeutic, including neurodegeneration, schizophrenia, and drug addiction. We tested the hypothesis that there is a link between actions of PPAR agonists and TE expression. We developed an innovative application of microarray data by mapping Illumina mouse WG-6 microarray probes to areas of the mouse genome that contain TEs. Using this information, we assessed the effects of systemic administration of three PPAR agonists with different PPAR subtype selectivity: fenofibrate, tesaglitazar, and bezafibrate, on TE probe expression in mouse brain [prefrontal cortex (PFC) and amygdala] and liver. We found that fenofibrate, and bezafibrate to a lesser extent, up-regulated probes mapped to retrotransposons: Short-Interspersed Elements (SINEs) and Long-Interspersed Elements (LINEs), in the PFC. Conversely, all PPAR agonists down-regulated LINEs and tesaglitazar and bezafibrate also down-regulated SINEs in liver. We built gene coexpression networks that partitioned the diverse transcriptional response to PPAR agonists into groups of probes with highly correlated expression patterns (modules). Most of the differentially expressed retrotransposons were within the same module, suggesting coordinated regulation of their expression, possibly by PPAR signaling. One TE module was conserved across tissues and was enriched with genes whose products participate in epigenetic regulation, suggesting that PPAR agonists affect TE expression via epigenetic mechanisms. Other enriched functional categories included phenotypes related to embryonic development and learning and memory, suggesting functional links between these biological processes and TE expression. In summary, these findings suggest mechanistic relationships between retrotransposons and PPAR agonists and provide a basis for future exploration of their functional roles in brain and liver.
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Affiliation(s)
- Laura B Ferguson
- Waggoner Center for Alcohol & Addiction Research, The University of Texas at Austin, Austin, TX, United States
| | - Lingling Zhang
- MOE Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao, China
| | - Shi Wang
- MOE Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Courtney Bridges
- Waggoner Center for Alcohol & Addiction Research, The University of Texas at Austin, Austin, TX, United States
| | - R Adron Harris
- Waggoner Center for Alcohol & Addiction Research, The University of Texas at Austin, Austin, TX, United States
| | - Igor Ponomarev
- Waggoner Center for Alcohol & Addiction Research, The University of Texas at Austin, Austin, TX, United States
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11
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Gardner EJ, Lam VK, Harris DN, Chuang NT, Scott EC, Pittard WS, Mills RE, Devine SE. The Mobile Element Locator Tool (MELT): population-scale mobile element discovery and biology. Genome Res 2017; 27:1916-1929. [PMID: 28855259 PMCID: PMC5668948 DOI: 10.1101/gr.218032.116] [Citation(s) in RCA: 214] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 08/07/2017] [Indexed: 01/22/2023]
Abstract
Mobile element insertions (MEIs) represent ∼25% of all structural variants in human genomes. Moreover, when they disrupt genes, MEIs can influence human traits and diseases. Therefore, MEIs should be fully discovered along with other forms of genetic variation in whole genome sequencing (WGS) projects involving population genetics, human diseases, and clinical genomics. Here, we describe the Mobile Element Locator Tool (MELT), which was developed as part of the 1000 Genomes Project to perform MEI discovery on a population scale. Using both Illumina WGS data and simulations, we demonstrate that MELT outperforms existing MEI discovery tools in terms of speed, scalability, specificity, and sensitivity, while also detecting a broader spectrum of MEI-associated features. Several run modes were developed to perform MEI discovery on local and cloud systems. In addition to using MELT to discover MEIs in modern humans as part of the 1000 Genomes Project, we also used it to discover MEIs in chimpanzees and ancient (Neanderthal and Denisovan) hominids. We detected diverse patterns of MEI stratification across these populations that likely were caused by (1) diverse rates of MEI production from source elements, (2) diverse patterns of MEI inheritance, and (3) the introgression of ancient MEIs into modern human genomes. Overall, our study provides the most comprehensive map of MEIs to date spanning chimpanzees, ancient hominids, and modern humans and reveals new aspects of MEI biology in these lineages. We also demonstrate that MELT is a robust platform for MEI discovery and analysis in a variety of experimental settings.
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Affiliation(s)
- Eugene J Gardner
- Program in Molecular Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.,Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - Vincent K Lam
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.,Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - Daniel N Harris
- Program in Molecular Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.,Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - Nelson T Chuang
- Program in Molecular Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.,Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.,Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.,Division of Gastroenterology, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - Emma C Scott
- Program in Molecular Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.,Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - W Stephen Pittard
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, USA
| | - Ryan E Mills
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA.,Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | | | - Scott E Devine
- Program in Molecular Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.,Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.,Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.,Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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12
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Rishishwar L, Wang L, Clayton EA, Mariño-Ramírez L, McDonald JF, Jordan IK. Population and clinical genetics of human transposable elements in the (post) genomic era. Mob Genet Elements 2017; 7:1-20. [PMID: 28228978 PMCID: PMC5305044 DOI: 10.1080/2159256x.2017.1280116] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 01/03/2017] [Accepted: 01/04/2017] [Indexed: 10/26/2022] Open
Abstract
Recent technological developments-in genomics, bioinformatics and high-throughput experimental techniques-are providing opportunities to study ongoing human transposable element (TE) activity at an unprecedented level of detail. It is now possible to characterize genome-wide collections of TE insertion sites for multiple human individuals, within and between populations, and for a variety of tissue types. Comparison of TE insertion site profiles between individuals captures the germline activity of TEs and reveals insertion site variants that segregate as polymorphisms among human populations, whereas comparison among tissue types ascertains somatic TE activity that generates cellular heterogeneity. In this review, we provide an overview of these new technologies and explore their implications for population and clinical genetic studies of human TEs. We cover both recent published results on human TE insertion activity as well as the prospects for future TE studies related to human evolution and health.
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Affiliation(s)
- Lavanya Rishishwar
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA; PanAmerican Bioinformatics Institute, Cali, Colombia; Applied Bioinformatics Laboratory, Atlanta, GA, USA
| | - Lu Wang
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA; PanAmerican Bioinformatics Institute, Cali, Colombia
| | - Evan A Clayton
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA; Ovarian Cancer Institute, Atlanta, GA, USA
| | - Leonardo Mariño-Ramírez
- PanAmerican Bioinformatics Institute, Cali, Colombia; National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - John F McDonald
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA; Ovarian Cancer Institute, Atlanta, GA, USA
| | - I King Jordan
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA; PanAmerican Bioinformatics Institute, Cali, Colombia; Applied Bioinformatics Laboratory, Atlanta, GA, USA
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13
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Hancks DC, Kazazian HH. Roles for retrotransposon insertions in human disease. Mob DNA 2016; 7:9. [PMID: 27158268 PMCID: PMC4859970 DOI: 10.1186/s13100-016-0065-9] [Citation(s) in RCA: 421] [Impact Index Per Article: 52.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 04/14/2016] [Indexed: 12/12/2022] Open
Abstract
Over evolutionary time, the dynamic nature of a genome is driven, in part, by the activity of transposable elements (TE) such as retrotransposons. On a shorter time scale it has been established that new TE insertions can result in single-gene disease in an individual. In humans, the non-LTR retrotransposon Long INterspersed Element-1 (LINE-1 or L1) is the only active autonomous TE. In addition to mobilizing its own RNA to new genomic locations via a "copy-and-paste" mechanism, LINE-1 is able to retrotranspose other RNAs including Alu, SVA, and occasionally cellular RNAs. To date in humans, 124 LINE-1-mediated insertions which result in genetic diseases have been reported. Disease causing LINE-1 insertions have provided a wealth of insight and the foundation for valuable tools to study these genomic parasites. In this review, we provide an overview of LINE-1 biology followed by highlights from new reports of LINE-1-mediated genetic disease in humans.
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Affiliation(s)
- Dustin C. Hancks
- />Eccles Institute of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT USA
| | - Haig H. Kazazian
- />McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins School of Medicine, Baltimore, MD USA
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14
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Distribution of CFTR mutations in the Czech population: Positive impact of integrated clinical and laboratory expertise, detection of novel/de novo alleles and relevance for related/derived populations. J Cyst Fibros 2013; 12:532-7. [DOI: 10.1016/j.jcf.2012.12.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 11/30/2012] [Accepted: 12/02/2012] [Indexed: 11/21/2022]
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15
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Retroelements in human disease. Gene 2013; 518:231-41. [PMID: 23333607 DOI: 10.1016/j.gene.2013.01.008] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 12/28/2012] [Accepted: 01/02/2013] [Indexed: 12/16/2022]
Abstract
Retroelements are an abundant class of noncoding DNAs present in about half of the human genome. Among them, L1, Alu and SVA are currently active. They "jump" by retrotransposition, shuffle genomic regions by 5' and 3' transduction, and promote or inhibit gene transcription by providing alternative promoters or generating antisense and/or regulatory noncoding RNAs. Recent data also suggest that retroelement insertions into exons and introns of genes induce different types of genetic disease, including cancer. Retroelements interfere with the expression of genes by inducing alternative splicing via exon skipping and exonization using cryptic splice sites, and by providing polyadenylation signals. Here we summarize our current understanding of the molecular mechanisms of retroelement-induced mutagenesis which causes fifty different types of human disease. We categorize these mutagenic effects according to eleven different mechanisms and show that most of them may be explained either by traditional exon definition or transcriptional interference, a previously unrecognized molecular mechanism. In summary, this review gives an overview of retroelement insertions in genes that cause significant changes in their transcription and cotranscriptional splicing and show a remarkable level of complexity.
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16
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Dridi S. Alu mobile elements: from junk DNA to genomic gems. SCIENTIFICA 2012; 2012:545328. [PMID: 24278713 PMCID: PMC3820591 DOI: 10.6064/2012/545328] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Accepted: 11/06/2012] [Indexed: 06/02/2023]
Abstract
Alus, the short interspersed repeated sequences (SINEs), are retrotransposons that litter the human genomes and have long been considered junk DNA. However, recent findings that these mobile elements are transcribed, both as distinct RNA polymerase III transcripts and as a part of RNA polymerase II transcripts, suggest biological functions and refute the notion that Alus are biologically unimportant. Indeed, Alu RNAs have been shown to control mRNA processing at several levels, to have complex regulatory functions such as transcriptional repression and modulating alternative splicing and to cause a host of human genetic diseases. Alu RNAs embedded in Pol II transcripts can promote evolution and proteome diversity, which further indicates that these mobile retroelements are in fact genomic gems rather than genomic junks.
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Affiliation(s)
- Sami Dridi
- Nutrition Research Institute, The University of North Carolina at Chapel Hill, 500 Laureate Way, Kannapolis, NC 28081, USA
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17
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Hancks DC, Kazazian HH. Active human retrotransposons: variation and disease. Curr Opin Genet Dev 2012; 22:191-203. [PMID: 22406018 DOI: 10.1016/j.gde.2012.02.006] [Citation(s) in RCA: 440] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 01/18/2012] [Accepted: 02/06/2012] [Indexed: 12/12/2022]
Abstract
Mobile DNAs, also known as transposons or 'jumping genes', are widespread in nature and comprise an estimated 45% of the human genome. Transposons are divided into two general classes based on their transposition intermediate (DNA or RNA). Only one subclass, the non-LTR retrotransposons, which includes the Long INterspersed Element-1 (LINE-1 or L1), is currently active in humans as indicated by 96 disease-causing insertions. The autonomous LINE-1 is capable of retrotransposing not only a copy of its own RNA in cis but also other RNAs (Alu, SINE-VNTR-Alu (SVA), U6) in trans to new genomic locations through an element encoded reverse transcriptase. L1 can also retrotranspose cellular mRNAs, resulting in processed pseudogene formation. Here, we highlight recent reports that update our understanding of human L1 retrotransposition and their role in disease. Finally we discuss studies that provide insights into the past and current activity of these retrotransposons, and shed light on not just when, but where, retrotransposition occurs and its part in genetic variation.
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Affiliation(s)
- Dustin C Hancks
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, United States
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18
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Cooper DN, Bacolla A, Férec C, Vasquez KM, Kehrer-Sawatzki H, Chen JM. On the sequence-directed nature of human gene mutation: the role of genomic architecture and the local DNA sequence environment in mediating gene mutations underlying human inherited disease. Hum Mutat 2011; 32:1075-99. [PMID: 21853507 PMCID: PMC3177966 DOI: 10.1002/humu.21557] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Accepted: 06/17/2011] [Indexed: 12/21/2022]
Abstract
Different types of human gene mutation may vary in size, from structural variants (SVs) to single base-pair substitutions, but what they all have in common is that their nature, size and location are often determined either by specific characteristics of the local DNA sequence environment or by higher order features of the genomic architecture. The human genome is now recognized to contain "pervasive architectural flaws" in that certain DNA sequences are inherently mutation prone by virtue of their base composition, sequence repetitivity and/or epigenetic modification. Here, we explore how the nature, location and frequency of different types of mutation causing inherited disease are shaped in large part, and often in remarkably predictable ways, by the local DNA sequence environment. The mutability of a given gene or genomic region may also be influenced indirectly by a variety of noncanonical (non-B) secondary structures whose formation is facilitated by the underlying DNA sequence. Since these non-B DNA structures can interfere with subsequent DNA replication and repair and may serve to increase mutation frequencies in generalized fashion (i.e., both in the context of subtle mutations and SVs), they have the potential to serve as a unifying concept in studies of mutational mechanisms underlying human inherited disease.
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Affiliation(s)
- David N Cooper
- Institute of Medical Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom.
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19
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Abstract
The number of known mutations in human nuclear genes, underlying or associated with human inherited disease, has now exceeded 100,000 in more than 3700 different genes (Human Gene Mutation Database). However, for a variety of reasons, this figure is likely to represent only a small proportion of the clinically relevant genetic variants that remain to be identified in the human genome (the 'mutome'). With the advent of next-generation sequencing, we are currently witnessing a revolution in medical genetics. In particular, whole-genome sequencing (WGS) has the potential to identify all disease-causing or disease-associated DNA variants in a given individual. Here, we use examples of recent advances in our understanding of mutational/pathogenic mechanisms to guide our thinking about possible locations outwith gene-coding sequences for those disease-causing or disease-associated variants that are likely so often to have been overlooked because of the inadequacy of current mutation screening protocols. Such considerations are important not only for improving mutation-screening strategies but also for enhancing the interpretation of findings derived from genome-wide association studies, whole-exome sequencing and WGS. An improved understanding of the human mutome will not only lead to the development of improved diagnostic testing procedures but should also improve our understanding of human genome biology.
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Affiliation(s)
- J M Chen
- Etablissement Français du Sang (EFS) - Bretagne, Brest, France.
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20
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The transposon-driven evolutionary origin and basis of histone deacetylase functions and limitations in disease prevention. Clin Epigenetics 2011; 2:97-112. [PMID: 22704332 PMCID: PMC3365375 DOI: 10.1007/s13148-011-0020-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Accepted: 01/03/2011] [Indexed: 12/19/2022] Open
Abstract
Histone deacetylases (HDACs) are homologous to prokaryotic enzymes that removed acetyl groups from non-histone proteins before the evolution of eukaryotic histones. Enzymes inherited from prokaryotes or from a common ancestor were adapted for histone deacetylation, while useful deacetylation of non-histone proteins was selectively retained. Histone deacetylation served to prevent transcriptions with pathological consequences, including the expression of viral DNA and the deletion or dysregulation of vital genes by random transposon insertions. Viruses are believed to have evolved from transposons, with transposons providing the earliest impetus of HDAC evolution. Because of the wide range of genes potentially affected by transposon insertions, the range of diseases that can be prevented by HDACs is vast and inclusive. Repressive chromatin modifications that may prevent transcription also include methylation of selective lysine residues of histones H3 and H4 and the methylation of selective DNA cytosines following specific histone lysine methylation. Methylation and acetylation of individual histone residues are mutually exclusive. While transposons were sources of disease to be prevented by HDAC evolution, they were also the source of numerous and valuable coding and regulatory sequences recruited by “molecular domestication.” Those sequences contribute to evolved complex transcription regulation in which components with contradictory effects, such as HDACs and HATs, may be coordinated and complementary. Within complex transcription regulation, however, HDACs remain ineffective as defense against some critical infectious and non-infectious diseases because evolutionary compromises have rendered their activity transient.
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21
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Quemener S, Chen JM, Chuzhanova N, Bénech C, Casals T, Macek M, Bienvenu T, McDevitt T, Farrell PM, Loumi O, Messaoud T, Cuppens H, Cutting GR, Stenson PD, Giteau K, Audrézet MP, Cooper DN, Férec C. Complete ascertainment of intragenic copy number mutations (CNMs) in the CFTR gene and its implications for CNM formation at other autosomal loci. Hum Mutat 2010; 31:421-8. [PMID: 20052766 DOI: 10.1002/humu.21196] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Over the last 20 years since the discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, more than 1,600 different putatively pathological CFTR mutations have been identified. Until now, however, copy number mutations (CNMs) involving the CFTR gene have not been methodically analyzed, resulting almost certainly in the underascertainment of CFTR gene duplications compared with deletions. Here, high-resolution array comparative genomic hybridization (averaging one interrogating probe every 95 bp) was used to analyze the entire length of the CFTR gene (189 kb) in 233 cystic fibrosis chromosomes lacking conventional mutations. We succeeded in identifying five duplication CNMs that would otherwise have been refractory to analysis. Based upon findings from this and other studies, we propose that deletion and duplication CNMs in the human autosomal genome are likely to be generated in the proportion of approximately 2-3:1. We further postulate that intragenic gene duplication CNMs in other disease loci may have been routinely underascertained. Finally, our analysis of +/-20 bp flanking each of the 40 CFTR breakpoints characterized at the DNA sequence level provide support for the emerging concept that non-B DNA conformations in combination with specific sequence motifs predispose to both recurring and nonrecurring genomic rearrangements.
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Affiliation(s)
- Sylvia Quemener
- INSERM U613, and Université de Bretagne Occidentale, 46 rue Félix Le Dantec, Brest, France
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22
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St Laurent G, Hammell N, McCaffrey TA. A LINE-1 component to human aging: do LINE elements exact a longevity cost for evolutionary advantage? Mech Ageing Dev 2010; 131:299-305. [PMID: 20346965 DOI: 10.1016/j.mad.2010.03.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 03/09/2010] [Accepted: 03/15/2010] [Indexed: 12/15/2022]
Abstract
Advancing age remains the largest risk factor for devastating diseases, such as heart disease, stroke, and cancer. The mechanisms by which advancing age predisposes to disease are now beginning to unfold, due in part, to genetic and environmental manipulations of longevity in lower organisms. Converging lines of evidence suggest that DNA damage may be a final common pathway linking several proposed mechanisms of aging. The present review forwards a theory for an additional aging pathway that involves modes of inherent genetic instability. Long interspersed nuclear elements (LINEs) are endogenous non-LTR retrotransposons that compose about 20% of the human genome. The LINE-1 (L1) gene products, ORF1p and ORF2p, possess mRNA binding, endonuclease, and reverse transcriptase activity that enable retrotransposition. While principally active only during embryogenesis, L1 transcripts are detected in adult somatic cells under certain conditions. The present hypothesis proposes that L1s act as an 'endogenous clock', slowly eroding genomic integrity by competing with the organism's double-strand break repair mechanism. Thus, while L1s are an accepted mechanism of genetic variation fueling evolution, it is proposed that longevity is negatively impacted by somatic L1 activity. The theory predicts testable hypotheses about the relationship between L1 activity, DNA repair, healthy aging, and longevity.
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Affiliation(s)
- Georges St Laurent
- The George Washington University Medical Center, Department of Medicine, Division of Genomic Medicine, 2300 I St. NW, Washington, DC 20037, United States
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23
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Detection and characterisation of large SERPINC1 deletions in type I inherited antithrombin deficiency. Hum Genet 2009; 127:45-53. [DOI: 10.1007/s00439-009-0742-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 09/05/2009] [Indexed: 10/20/2022]
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24
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Comeaux MS, Roy-Engel AM, Hedges DJ, Deininger PL. Diverse cis factors controlling Alu retrotransposition: what causes Alu elements to die? Genome Res 2009; 19:545-55. [PMID: 19273617 DOI: 10.1101/gr.089789.108] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The human genome contains nearly 1.1 million Alu elements comprising roughly 11% of its total DNA content. Alu elements use a copy and paste retrotransposition mechanism that can result in de novo disease insertion alleles. There are nearly 900,000 old Alu elements from subfamilies S and J that appear to be almost completely inactive, and about 200,000 from subfamily Y or younger, which include a few thousand copies of the Ya5 subfamily which makes up the majority of current activity. Given the much higher copy number of the older Alu subfamilies, it is not known why all of the active Alu elements belong to the younger subfamilies. We present a systematic analysis evaluating the observed sequence variation in the different sections of an Alu element on retrotransposition. The length of the longest number of uninterrupted adenines in the A-tail, the degree of A-tail heterogeneity, the length of the 3' unique end after the A-tail and before the RNA polymerase III terminator, and random mutations found in the right monomer all modulate the retrotransposition efficiency. These changes occur over different evolutionary time frames. The combined impact of sequence changes in all of these regions explains why young Alus are currently causing disease through retrotransposition, and the old Alus have lost their ability to retrotranspose. We present a predictive model to evaluate the retrotransposition capability of individual Alu elements and successfully applied it to identify the first putative source element for a disease-causing Alu insertion in a patient with cystic fibrosis.
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Affiliation(s)
- Matthew S Comeaux
- Tulane Cancer Center and Dept. of Epidemiology, Tulane University Health Sciences Center, New Orleans, Louisiana 70112, USA
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25
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Belancio VP, Hedges DJ, Deininger P. Mammalian non-LTR retrotransposons: for better or worse, in sickness and in health. Genome Res 2008; 18:343-58. [PMID: 18256243 DOI: 10.1101/gr.5558208] [Citation(s) in RCA: 224] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Transposable elements (TEs) have shared an exceptionally long coexistence with their host organisms and have come to occupy a significant fraction of eukaryotic genomes. The bulk of the expansion occurring within mammalian genomes has arisen from the activity of type I retrotransposons, which amplify in a "copy-and-paste" fashion through an RNA intermediate. For better or worse, the sequences of these retrotransposons are now wedded to the genomes of their mammalian hosts. Although there are several reported instances of the positive contribution of mobile elements to their host genomes, these discoveries have occurred alongside growing evidence of the role of TEs in human disease and genetic instability. Here we examine, with a particular emphasis on human retrotransposon activity, several newly discovered aspects of mammalian retrotransposon biology. We consider their potential impact on host biology as well as their ultimate implications for the nature of the TE-host relationship.
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Affiliation(s)
- Victoria P Belancio
- Tulane Cancer Center and Department of Epidemiology, Tulane University Health Sciences Center, New Orleans, Louisiana 70112, USA
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