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Ivanova AD, Semenova ML. Chromosomal Aberrations As a Biological Phenomenon in Human Embryonic Development. Acta Naturae 2023; 15:27-36. [PMID: 37908766 PMCID: PMC10615189 DOI: 10.32607/actanaturae.25255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 08/09/2023] [Indexed: 11/02/2023] Open
Abstract
Frequent chromosomal abnormalities are a distinctive feature of early embryonic development in mammals, especially humans. Aneuploidy is considered as a contributing factor to failed embryo implantation and spontaneous abortions. In the case of chromosomal mosaicism, its effect on the potency of embryos to normally develop has not been sufficiently studied. Although, a significant percentage of chromosomal defects in early human embryos are currently believed to be associated with the features of clinical and laboratory protocols, in this review, we focus on the biological mechanisms associated with chromosomal abnormalities. In particular, we address the main events in oocyte meiosis that affects not only the genetic status of an unfertilized oocyte, but also further embryo viability, and analyze the features of first cleavage divisions and the causes of frequent chromosomal errors in early embryonic development. In addition, we discuss current data on self-correction of the chromosomal status in early embryos.
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Affiliation(s)
- A. D. Ivanova
- Lomonosov Moscow State University, Biological Faculty, Moscow, 119991 Russian Federation
| | - M. L. Semenova
- Lomonosov Moscow State University, Biological Faculty, Moscow, 119991 Russian Federation
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2
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Coll L, Parriego M, Mateo S, García-Monclús S, Rodríguez I, Boada M, Coroleu B, Polyzos NP, Vidal F, Veiga A. Prevalence, types and possible factors influencing mosaicism in IVF blastocysts: results from a single setting. Reprod Biomed Online 2020; 42:55-65. [PMID: 33153932 DOI: 10.1016/j.rbmo.2020.09.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/08/2020] [Accepted: 09/29/2020] [Indexed: 12/11/2022]
Abstract
RESEARCH QUESTION Are intrinsic or extrinsic factors associated with embryo mosaicism prevalence in IVF cycles? DESIGN Retrospective cohort study of preimplantation genetic testing for aneuploidy (PGT-A) cycles carried out at a university-affiliated IVF clinic between October 2017 and October 2019. Trophectoderm biopsies were analysed by next generation sequencing. Mosaicism prevalence, type of anomaly and the chromosomes involved were analysed. Intrinsic and extrinsic factors potentially inducing mosaicism were studied: maternal and paternal age, antral follicle count, cumulus-oocyte complexes retrieved, female body mass index, PGT-A indication, sperm concentration, total dosage of gonadotrophins, embryo quality and day of blastocyst formation, single-step commercial media used and biopsy operator. RESULTS Overall prevalence of mosaicism in our PGT-A setting was 13.9%. In segmental mosaicism, larger chromosomes tended to be more affected, which was not observed in whole-chromosome mosaicism. Additionally, segmental mosaicism was mostly observed in monosomy (69.6%; P < 0.01) compared with whole-chromosome mosaicism (49.7% monosomies versus 50.3% trisomies; P = 0.83). Although a high inter-patient variability was observed, only paternal age showed a positive association with mosaicism (adjusted OR 1.26, 95% CI 1.02 to 1.54) among the analysed variables. CONCLUSIONS Our results suggest remarkable differences in the mechanisms generating segmental and whole-chromosome mosaicism, indicating that they may deserve different consideration when studying them and when prioritizing them for transfer. Male factor seems to be associated with mosaicism and may be worthy of specific assessment in future studies.
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Affiliation(s)
- Lluc Coll
- Reproductive Medicine Unit, Department of Obstetrics, Gynaecology and Reproduction, Dexeus Mujer, Hospital Universitari Dexeus, Gran Via Carles III, 71-75, Barcelona 08028, Spain.
| | - Mònica Parriego
- Reproductive Medicine Unit, Department of Obstetrics, Gynaecology and Reproduction, Dexeus Mujer, Hospital Universitari Dexeus, Gran Via Carles III, 71-75, Barcelona 08028, Spain
| | - Sílvia Mateo
- Reproductive Medicine Unit, Department of Obstetrics, Gynaecology and Reproduction, Dexeus Mujer, Hospital Universitari Dexeus, Gran Via Carles III, 71-75, Barcelona 08028, Spain
| | - Sílvia García-Monclús
- Reproductive Medicine Unit, Department of Obstetrics, Gynaecology and Reproduction, Dexeus Mujer, Hospital Universitari Dexeus, Gran Via Carles III, 71-75, Barcelona 08028, Spain
| | - Ignacio Rodríguez
- Reproductive Medicine Unit, Department of Obstetrics, Gynaecology and Reproduction, Dexeus Mujer, Hospital Universitari Dexeus, Gran Via Carles III, 71-75, Barcelona 08028, Spain
| | - Montserrat Boada
- Reproductive Medicine Unit, Department of Obstetrics, Gynaecology and Reproduction, Dexeus Mujer, Hospital Universitari Dexeus, Gran Via Carles III, 71-75, Barcelona 08028, Spain
| | - Buenaventura Coroleu
- Reproductive Medicine Unit, Department of Obstetrics, Gynaecology and Reproduction, Dexeus Mujer, Hospital Universitari Dexeus, Gran Via Carles III, 71-75, Barcelona 08028, Spain
| | - Nikolaos P Polyzos
- Reproductive Medicine Unit, Department of Obstetrics, Gynaecology and Reproduction, Dexeus Mujer, Hospital Universitari Dexeus, Gran Via Carles III, 71-75, Barcelona 08028, Spain
| | - Francesca Vidal
- Unitat de Biologia Cellular, Facultat de Biociències, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | - Anna Veiga
- Reproductive Medicine Unit, Department of Obstetrics, Gynaecology and Reproduction, Dexeus Mujer, Hospital Universitari Dexeus, Gran Via Carles III, 71-75, Barcelona 08028, Spain; Barcelona Stem Cell Bank, IDIBELL Programme for Regenerative Medicine, 08908 L'Hospitalet de Llobregat, Spain
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3
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Preimplantation Genetic Testing for Chromosomal Abnormalities: Aneuploidy, Mosaicism, and Structural Rearrangements. Genes (Basel) 2020; 11:genes11060602. [PMID: 32485954 PMCID: PMC7349251 DOI: 10.3390/genes11060602] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 05/25/2020] [Accepted: 05/27/2020] [Indexed: 12/18/2022] Open
Abstract
There is a high incidence of chromosomal abnormalities in early human embryos, whether they are generated by natural conception or by assisted reproductive technologies (ART). Cells with chromosomal copy number deviations or chromosome structural rearrangements can compromise the viability of embryos; much of the naturally low human fecundity as well as low success rates of ART can be ascribed to these cytogenetic defects. Chromosomal anomalies are also responsible for a large proportion of miscarriages and congenital disorders. There is therefore tremendous value in methods that identify embryos containing chromosomal abnormalities before intrauterine transfer to a patient being treated for infertility—the goal being the exclusion of affected embryos in order to improve clinical outcomes. This is the rationale behind preimplantation genetic testing for aneuploidy (PGT-A) and structural rearrangements (-SR). Contemporary methods are capable of much more than detecting whole chromosome abnormalities (e.g., monosomy/trisomy). Technical enhancements and increased resolution and sensitivity permit the identification of chromosomal mosaicism (embryos containing a mix of normal and abnormal cells), as well as the detection of sub-chromosomal abnormalities such as segmental deletions and duplications. Earlier approaches to screening for chromosomal abnormalities yielded a binary result of normal versus abnormal, but the new refinements in the system call for new categories, each with specific clinical outcomes and nuances for clinical management. This review intends to give an overview of PGT-A and -SR, emphasizing recent advances and areas of active development.
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Popovic M, Dhaenens L, Boel A, Menten B, Heindryckx B. Chromosomal mosaicism in human blastocysts: the ultimate diagnostic dilemma. Hum Reprod Update 2020; 26:313-334. [DOI: 10.1093/humupd/dmz050] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 11/29/2019] [Indexed: 12/30/2022] Open
Abstract
Abstract
BACKGROUND
Trophectoderm (TE) biopsy and next generation sequencing (NGS) are currently the preferred techniques for preimplantation genetic testing for aneuploidies (PGT-A). Although this approach delivered important improvements over previous testing strategies, increased sensitivity has also prompted a rise in diagnoses of uncertain clinical significance. This includes reports of chromosomal mosaicism, suggesting the presence of karyotypically distinct cells within a single TE biopsy. Given that PGT-A relies on the chromosomal constitution of the biopsied cells being representative of the entire embryo, the prevalence and clinical implications of blastocyst mosaicism continue to generate considerable controversy.
OBJECTIVE AND RATIONALE
The objective of this review was to evaluate existing scientific evidence regarding the prevalence and impact of chromosomal mosaicism in human blastocysts. We discuss insights from a biological, technical and clinical perspective to examine the implications of this diagnostic dilemma for PGT-A.
SEARCH METHODS
The PubMed and Google Scholar databases were used to search peer-reviewed publications using the following terms: ‘chromosomal mosaicism’, ‘human’, ‘embryo’, ‘blastocyst’, ‘implantation’, ‘next generation sequencing’ and ‘clinical management’ in combination with other keywords related to the subject area. Relevant articles in the English language, published until October 2019 were critically discussed.
OUTCOMES
Chromosomal mosaicism predominately results from errors in mitosis following fertilization. Although it appears to be less pervasive at later developmental stages, establishing the true prevalence of mosaicism in human blastocysts remains exceedingly challenging. In a clinical context, blastocyst mosaicism can only be reported based on a single TE biopsy and has been ascribed to 2–13% of embryos tested using NGS. Conversely, data from NGS studies disaggregating whole embryos suggests that mosaicism may be present in up to ~50% of blastocysts. However, differences in testing and reporting strategies, analysis platforms and the number of cells sampled inherently overshadow current data, while added uncertainties emanate from technical artefacts. Moreover, laboratory factors and aspects of in vitro culture generate further variability. Outcome data following the transfer of blastocysts diagnosed as mosaic remain limited. Current studies suggest that the transfer of putative mosaic embryos may lead to healthy live births, but also results in significantly reduced ongoing pregnancy rates compared to the transfer of euploid blastocysts. Observations that a subset of mosaic blastocysts has the capacity to develop normally have sparked discussions regarding the ability of embryos to self-correct. However, there is currently no direct evidence to support this assumption. Nevertheless, the exclusion of mosaic blastocysts results in fewer embryos available for transfer, which may inevitably compromise treatment outcomes.
WIDER IMPLICATIONS
Chromosomal mosaicism in human blastocysts remains a perpetual diagnostic and clinical dilemma in the context of PGT-A. This review offers an important scientific resource, informing about the challenges, risks and value of diagnosing mosaicism. Elucidating these uncertainties will ultimately pave the way towards improved clinical and patient management.
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Affiliation(s)
- Mina Popovic
- Ghent-Fertility and Stem Cell Team (G-FAST), Department for Reproductive Medicine, Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium
| | - Lien Dhaenens
- Ghent-Fertility and Stem Cell Team (G-FAST), Department for Reproductive Medicine, Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium
| | - Annekatrien Boel
- Ghent-Fertility and Stem Cell Team (G-FAST), Department for Reproductive Medicine, Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium
| | - Björn Menten
- Center for Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium
| | - Björn Heindryckx
- Ghent-Fertility and Stem Cell Team (G-FAST), Department for Reproductive Medicine, Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium
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5
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The mechanisms and clinical application of mosaicism in preimplantation embryos. J Assist Reprod Genet 2019; 37:497-508. [PMID: 31838629 DOI: 10.1007/s10815-019-01656-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 12/05/2019] [Indexed: 02/08/2023] Open
Abstract
Embryos containing distinct cell lines are referred to as mosaic embryos, which are considered to be caused by mitotic errors in chromosome segregation during preimplantation development. As the accuracy and resolution of detection techniques improve, more and more mosaic embryos were identified recently. The impacts of mosaic embryos on survival and potential pregnancy outcome have been reported to be diverse in different studies. Because of the universality and clinical significance of mosaicism, it is essential to unravel the mechanisms and consequences with regard to this phenomenon in human pre- and post-implantation embryos. The purpose of this review is to explore the mechanisms, causes of mosaicism, and the development of pre- and post-implantation mosaic embryos in the light of recent emerging data, with the aim of providing new references for clinical applications.
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Griffin DK, Ogur C. Chromosomal analysis in IVF: just how useful is it? Reproduction 2018; 156:F29-F50. [PMID: 29945889 DOI: 10.1530/rep-17-0683] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 03/23/2018] [Indexed: 12/11/2022]
Abstract
Designed to minimize chances of genetically abnormal embryos, preimplantation genetic diagnosis (PGD) involves in vitro fertilization (IVF), embryo biopsy, diagnosis and selective embryo transfer. Preimplantation genetic testing for aneuploidy (PGT-A) aims to avoid miscarriage and live born trisomic offspring and to improve IVF success. Diagnostic approaches include fluorescence in situ hybridization (FISH) and more contemporary comprehensive chromosome screening (CCS) including array comparative genomic hybridization (aCGH), quantitative polymerase chain reaction (PCR), next-generation sequencing (NGS) and karyomapping. NGS has an improved dynamic range, and karyomapping can detect chromosomal and monogenic disorders simultaneously. Mosaicism (commonplace in human embryos) can arise by several mechanisms; those arising initially meiotically (but with a subsequent post-zygotic 'trisomy rescue' event) usually lead to adverse outcomes, whereas the extent to which mosaics that are initially chromosomally normal (but then arise purely post-zygotically) can lead to unaffected live births is uncertain. Polar body (PB) biopsy is the least common sampling method, having drawbacks including cost and inability to detect any paternal contribution. Historically, cleavage-stage (blastomere) biopsy has been the most popular; however, higher abnormality levels, mosaicism and potential for embryo damage have led to it being superseded by blastocyst (trophectoderm - TE) biopsy, which provides more cells for analysis. Improved biopsy, diagnosis and freeze-all strategies collectively have the potential to revolutionize PGT-A, and there is increasing evidence of their combined efficacy. Nonetheless, PGT-A continues to attract criticism, prompting questions of when we consider the evidence base sufficient to justify routine PGT-A? Basic biological research is essential to address unanswered questions concerning the chromosome complement of human embryos, and we thus entreat companies, governments and charities to fund more. This will benefit both IVF patients and prospective parents at risk of aneuploid offspring following natural conception. The aim of this review is to appraise the 'state of the art' in terms of PGT-A, including the controversial areas, and to suggest a practical 'way forward' in terms of future diagnosis and applied research.
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Affiliation(s)
- Darren K Griffin
- School of BiosciencesCentre for Interdisciplinary Studies of Reproduction, University of Kent, Canterbury, UK
| | - Cagri Ogur
- Bahceci Genetic Diagnosis Centerİstanbul, Turkey.,Department of BioengineeringYildiz Technical University, İstanbul, Turkey
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7
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Abstract
INTRODUCTION Preimplantation genetic diagnosis and screening (PGD/PGS) has been applied clinically for >25 years however inherent drawbacks include the necessity to tailor each case to the trait in question, and that technology to detect monogenic and chromosomal disorders respectively is fundamentally different. Areas covered: The area of preimplantation genetics has evolved over the last 25 years, adapting to changes in technology and the need for more efficient, streamlined diagnoses. Karyomapping allows the determination of inheritance from the (grand)parental haplobocks through assembly of inherited chromosomal segments. The output displays homologous chromosomes, crossovers and the genetic status of the embryos by linkage comparison, as well as chromosomal disorders. It also allows for determination of heterozygous SNP calls, avoiding the risks of allele dropout, a common problem with other PGD techniques. Manuscripts documenting the evolution of preimplantation genetics, especially those investigating technologies that would simultaneously detect monogenic and chromosomal disorders, were selected for review. Expert commentary: Karyomapping is currently available for detection of single gene disorders; ~1000 clinics worldwide offer it (via ~20 diagnostic laboratories) and ~2500 cases have been performed. Due an inability to detect post-zygotic trisomy reliably however and confounding problems of embryo mosaicism, karyomapping has yet to be applied clinically for detection of chromosome disorders.
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Affiliation(s)
- Rebecca L Gould
- a The Bridge Centre , London , UK.,b School of Biological Sciences , University of Kent , Canterbury , UK
| | - Darren K Griffin
- b School of Biological Sciences , University of Kent , Canterbury , UK
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8
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Saintas E, Abrahams L, Ahmad GT, Ajakaiye AOM, AlHumaidi ASHAM, Ashmore-Harris C, Clark I, Dura UK, Fixmer CN, Ike-Morris C, Mato Prado M, Mccullough D, Mishra S, Schöler KMU, Timur H, Williamson MDC, Alatsatianos M, Bahsoun B, Blackburn E, Hogwood CE, Lithgow PE, Rowe M, Yiangou L, Rothweiler F, Cinatl J, Zehner R, Baines AJ, Garrett MD, Gourlay CW, Griffin DK, Gullick WJ, Hargreaves E, Howard MJ, Lloyd DR, Rossman JS, Smales CM, Tsaousis AD, von der Haar T, Wass MN, Michaelis M. Acquired resistance to oxaliplatin is not directly associated with increased resistance to DNA damage in SK-N-ASrOXALI4000, a newly established oxaliplatin-resistant sub-line of the neuroblastoma cell line SK-N-AS. PLoS One 2017; 12:e0172140. [PMID: 28192521 PMCID: PMC5305101 DOI: 10.1371/journal.pone.0172140] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 01/31/2017] [Indexed: 12/20/2022] Open
Abstract
The formation of acquired drug resistance is a major reason for the failure of anti-cancer therapies after initial response. Here, we introduce a novel model of acquired oxaliplatin resistance, a sub-line of the non-MYCN-amplified neuroblastoma cell line SK-N-AS that was adapted to growth in the presence of 4000 ng/mL oxaliplatin (SK-N-ASrOXALI4000). SK-N-ASrOXALI4000 cells displayed enhanced chromosomal aberrations compared to SK-N-AS, as indicated by 24-chromosome fluorescence in situ hybridisation. Moreover, SK-N-ASrOXALI4000 cells were resistant not only to oxaliplatin but also to the two other commonly used anti-cancer platinum agents cisplatin and carboplatin. SK-N-ASrOXALI4000 cells exhibited a stable resistance phenotype that was not affected by culturing the cells for 10 weeks in the absence of oxaliplatin. Interestingly, SK-N-ASrOXALI4000 cells showed no cross resistance to gemcitabine and increased sensitivity to doxorubicin and UVC radiation, alternative treatments that like platinum drugs target DNA integrity. Notably, UVC-induced DNA damage is thought to be predominantly repaired by nucleotide excision repair and nucleotide excision repair has been described as the main oxaliplatin-induced DNA damage repair system. SK-N-ASrOXALI4000 cells were also more sensitive to lysis by influenza A virus, a candidate for oncolytic therapy, than SK-N-AS cells. In conclusion, we introduce a novel oxaliplatin resistance model. The oxaliplatin resistance mechanisms in SK-N-ASrOXALI4000 cells appear to be complex and not to directly depend on enhanced DNA repair capacity. Models of oxaliplatin resistance are of particular relevance since research on platinum drugs has so far predominantly focused on cisplatin and carboplatin.
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Affiliation(s)
- Emily Saintas
- School of Biosciences, University of Kent, Canterbury, United Kingdom
- Industrial Biotechnology Centre, University of Kent, Canterbury, United Kingdom
| | - Liam Abrahams
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Gulshan T. Ahmad
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | | | | | | | - Iain Clark
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Usha K. Dura
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Carine N. Fixmer
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | | | - Mireia Mato Prado
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | | | - Shishir Mishra
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | | | - Husne Timur
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | | | | | - Basma Bahsoun
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Edith Blackburn
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Catherine E. Hogwood
- School of Biosciences, University of Kent, Canterbury, United Kingdom
- Industrial Biotechnology Centre, University of Kent, Canterbury, United Kingdom
| | - Pamela E. Lithgow
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Michelle Rowe
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Lyto Yiangou
- School of Biosciences, University of Kent, Canterbury, United Kingdom
- Industrial Biotechnology Centre, University of Kent, Canterbury, United Kingdom
| | - Florian Rothweiler
- Institut für Medizinische Virologie, Klinikum der Goethe-Universität, Frankfurt am Main, Germany
| | - Jindrich Cinatl
- Institut für Medizinische Virologie, Klinikum der Goethe-Universität, Frankfurt am Main, Germany
| | - Richard Zehner
- Institut für Rechtsmedizin, Klinikum der Goethe-Universität, Frankfurt am Main, Germany
| | - Anthony J. Baines
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | | | | | - Darren K. Griffin
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | | | - Emma Hargreaves
- School of Biosciences, University of Kent, Canterbury, United Kingdom
- Industrial Biotechnology Centre, University of Kent, Canterbury, United Kingdom
| | - Mark J. Howard
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Daniel R. Lloyd
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Jeremy S. Rossman
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - C. Mark Smales
- School of Biosciences, University of Kent, Canterbury, United Kingdom
- Industrial Biotechnology Centre, University of Kent, Canterbury, United Kingdom
| | | | | | - Mark N. Wass
- School of Biosciences, University of Kent, Canterbury, United Kingdom
- Industrial Biotechnology Centre, University of Kent, Canterbury, United Kingdom
| | - Martin Michaelis
- School of Biosciences, University of Kent, Canterbury, United Kingdom
- Industrial Biotechnology Centre, University of Kent, Canterbury, United Kingdom
- * E-mail:
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9
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Abstract
Post-zygotic variation refers to genetic changes that arise in the soma of an individual and that are not usually inherited by the next generation. Although there is a paucity of research on such variation, emerging studies show that it is common: individuals are complex mosaics of genetically distinct cells, to such an extent that no two somatic cells are likely to have the exact same genome. Although most types of mutation can be involved in post-zygotic variation, structural genetic variants are likely to leave the largest genomic footprint. Somatic variation has diverse physiological roles and pathological consequences, particularly when acquired variants influence the clonal trajectories of the affected cells. Post-zygotic variation is an important confounder in medical genetic testing and a promising avenue for research: future studies could involve analyses of sorted and single cells from multiple tissue types to fully explore its potential.
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Taylor TH, Griffin DK, Katz SL, Crain JL, Johnson L, Gitlin S. Technique to ‘Map' Chromosomal Mosaicism at the Blastocyst Stage. Cytogenet Genome Res 2016; 149:262-266. [DOI: 10.1159/000449051] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Indexed: 11/19/2022] Open
Abstract
The purpose of this study was to identify a technique that allows for comprehensive chromosome screening (CCS) of individual cells within human blastocysts along with the approximation of their location in the trophectoderm relative to the inner cell mass (ICM). This proof-of-concept study will allow for a greater understanding of chromosomal mosaicism at the blastocyst stage and the mechanisms by which mosaicism arises. One blastocyst was held by a holding pipette and the ICM was removed. While still being held, the blastocyst was further biopsied into quadrants. To separate the individual cells from the biopsied sections, the sections were placed in calcium/magnesium-free medium with serum for 20 min. A holding pipette was used to aspirate the sections until individual cells were isolated. Individual cells from each section were placed into PCR tubes and prepped for aCGH. A total of 18 cells were used for analysis, of which 15 (83.3%) amplified and provided a result and 3 (16.7%) did not. Fifteen cells were isolated from the trophectoderm; 13 (86.7%) provided an aCGH result, while 2 (13.3%) did not amplify. Twelve cells were euploid (46,XY), while 1 was complex abnormal (44,XY), presenting with monosomy 7, 10, 11, 13, and 19, and trisomy 14, 15, and 21. A total of 3 cells were isolated from the ICM; 2 were euploid (46,XY) and 1 did not amplify. Here, we expand on a previously published technique which disassociates biopsied sections of the blastocyst into individual cells. Since the blastocyst sections were biopsied in regard to the position of the ICM, it was possible to reconstruct a virtual image of the blastocyst while presenting each cell's individual CCS results.
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11
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Hochstenbach R, Nowakowska B, Volleth M, Ummels A, Kutkowska-Kaźmierczak A, Obersztyn E, Ziemkiewicz K, Gerloff C, Schanze D, Zenker M, Muschke P, Schanze I, Poot M, Liehr T. Multiple Small Supernumerary Marker Chromosomes Resulting from Maternal Meiosis I or II Errors. Mol Syndromol 2016; 6:210-21. [PMID: 26997941 PMCID: PMC4772618 DOI: 10.1159/000441408] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2015] [Indexed: 01/11/2023] Open
Abstract
We present 2 cases with multiple de novo supernumerary marker chromosomes (sSMCs), each derived from a different chromosome. In a prenatal case, we found mosaicism for an sSMC(4), sSMC(6), sSMC(9), sSMC(14) and sSMC(22), while a postnatal case had an sSMC(4), sSMC(8) and an sSMC(11). SNP-marker segregation indicated that the sSMC(4) resulted from a maternal meiosis II error in the prenatal case. Segregation of short tandem repeat markers on the sSMC(8) was consistent with a maternal meiosis I error in the postnatal case. In the latter, a boy with developmental/psychomotor delay, autism, hyperactivity, speech delay, and hypotonia, the sSMC(8) was present at the highest frequency in blood. By comparison to other patients with a corresponding duplication, a minimal region of overlap for the phenotype was identified, with CHRNB3 and CHRNA6 as dosage-sensitive candidate genes. These genes encode subunits of nicotinic acetylcholine receptors (nAChRs). We propose that overproduction of these subunits leads to perturbed component stoichiometries with dominant negative effects on the function of nAChRs, as was shown by others in vitro. With the limitation that in each case only one sSMC could be studied, our findings demonstrate that different meiotic errors lead to multiple sSMCs. We relate our findings to age-related aneuploidy in female meiosis and propose that predivision sister-chromatid separation during meiosis I or II, or both, may generate multiple sSMCs.
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Affiliation(s)
- Ron Hochstenbach
- Division of Biomedical Genetics, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Beata Nowakowska
- Department of Medical Genetics, Institute of the Mother and Child, Warsaw, Poland
| | | | - Amber Ummels
- Division of Biomedical Genetics, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Ewa Obersztyn
- Department of Medical Genetics, Institute of the Mother and Child, Warsaw, Poland
| | - Kamila Ziemkiewicz
- Department of Medical Genetics, Institute of the Mother and Child, Warsaw, Poland
| | - Claudia Gerloff
- University Women's Clinic, Otto-von-Guericke University, Magdeburg, Germany
| | | | | | | | - Ina Schanze
- Department of Human Genetics, Magdeburg, Germany
| | - Martin Poot
- Division of Biomedical Genetics, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Thomas Liehr
- Department of Human Genetics, University Clinic, Jena, Germany
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12
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Abstract
The paternal contribution to fertilization and embryogenesis is frequently overlooked as the spermatozoon is often considered to be a silent vessel whose only function is to safely deliver the paternal genome to the maternal oocyte. In this article, we hope to demonstrate that this perception is far from the truth. Typically, infertile men have been unable to conceive naturally (or through regular IVF), and therefore, a perturbation of the genetic integrity of sperm heads in infertile males has been under-considered. The advent of intracytoplasmic sperm injection (ICSI) however has led to very successful treatment of male factor infertility and subsequent widespread use in IVF clinics worldwide. Until recently, little concern has been raised about the genetic quality of sperm in ICSI patients or the impact genetic aberrations could have on fertility and embryogenesis. This review highlights the importance of chromatin packaging in the sperm nucleus as essential for the establishment and maintenance of a viable pregnancy.
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Gollo Dantas A, Bortolai A, Moysés-Oliveira M, Takeno Herrero S, Azoubel Antunes A, Tavares Costa-Carvalho B, Ayres Meloni V, Melaragno MI. 22q11.2 Deletion Syndrome due to a Translocation t(6;22) in a Patient Conceived via in vitro Fertilization. Mol Syndromol 2015; 6:242-7. [PMID: 26997945 DOI: 10.1159/000441243] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2015] [Indexed: 11/19/2022] Open
Abstract
We report on a patient conceived via in vitro fertilization (IVF) with a 22q11.2 deletion due to an unusual unbalanced translocation involving chromosomes 6 and 22 in a karyotype with 45 chromosomes. Cytogenomic studies showed that the patient has a 3.3-Mb deletion of chromosome 22q and a 0.4-Mb deletion of chromosome 6p, which resulted in haploinsufficiency of the genes responsible for the 22q11.2 deletion syndrome and also of the IRF4 gene, a member of the interferon regulatory factor family of transcription factors, which is expressed in the immune system cells. The rearrangement could be due to the manipulation of the embryo or as a sporadic event unrelated to IVF. Translocation involving chromosome 22 in a karyotype with 45 chromosomes is a rare event, with no previous reports involving chromosomes 6p and 22q.
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Affiliation(s)
- Anelisa Gollo Dantas
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, Brazil
| | - Adriana Bortolai
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, Brazil; Cytogenetics Division, Hospital do Servidor Público do Estado de São Paulo, São Paulo, Brazil
| | - Mariana Moysés-Oliveira
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, Brazil
| | - Sylvia Takeno Herrero
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, Brazil
| | | | | | - Vera Ayres Meloni
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, Brazil
| | - Maria Isabel Melaragno
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, Brazil
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Ioannou D, Kandukuri L, Simpson JL, Tempest HG. Chromosome territory repositioning induced by PHA-activation of lymphocytes: A 2D and 3D appraisal. Mol Cytogenet 2015; 8:47. [PMID: 26146516 PMCID: PMC4490598 DOI: 10.1186/s13039-015-0146-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 05/14/2015] [Indexed: 11/26/2022] Open
Abstract
Background Genomes and by extension chromosome territories (CTs) in a variety of organisms exhibit nonrandom organization within interphase nuclei. CTs are susceptible to movement upon induction by a variety of stimuli, including: cell differentiation, growth factors, genotoxic agents, proliferating status, and stimulants that induce novel transcription profiles. These findings suggest nuclear architecture can undergo reorganization, providing support for a functional significance of CT organization. The effect of the initiation of transcription on global scale chromatin architecture has been underexplored. This study investigates the organization of all 24 human chromosomes in lymphocytes from two individuals in resting and phytohaemagglutinin activated lymphocytes using 2D and 3D approaches. Results The radial organization of CTs in lymphocytes in both resting and activated lymphocytes follows a gene-density pattern. However, CT organization in activated nuclei appears less constrained exhibiting a more random organization. We report differences in the spatial relationship between homologous and heterologous CTs in activated nuclei. In addition, a reproducible radial hierarchy of CTs was identified and evidence of a CT repositioning was observed in activated nuclei using both 2D and 3D approaches. Conclusions Alterations between resting and activated lymphocytes could be adaptation of CTs to the new transcription profile and possibly the formation of new neighborhoods of interest or interaction of CTs with nuclear landmarks. The increased distances between homologous and heterologous CTs in activated lymphocytes could be a reflection of a defensive mechanism to reduce potential interaction to prevent any structural chromosome abnormalities (e.g. translocations) as a result of DNA damage that increases during lymphocyte activation.
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Affiliation(s)
- Dimitrios Ioannou
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199 USA
| | - Lakshmi Kandukuri
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199 USA ; Present address Centre for Cellular and Molecular Biology (CCMB), Council of Scientific and Industrial Research (CSIR) Uppal Road, Hyderabad, 500 007 India
| | - Joe Leigh Simpson
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199 USA
| | - Helen Ghislaine Tempest
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199 USA ; Biomolecular Sciences Institute, Florida International University, Miami, FL 33199 USA
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15
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A high incidence of chromosome abnormalities in two-cell stage porcine IVP embryos. J Appl Genet 2015; 56:515-523. [PMID: 25801469 DOI: 10.1007/s13353-015-0280-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 01/09/2015] [Accepted: 03/04/2015] [Indexed: 10/23/2022]
Abstract
In pigs, in vitro production is difficult with a high occurrence of polyspermy and low blastocyst formation rates. To test the hypothesis that this may, at least in part, be due to chromosomal errors, we employed whole genome amplification and comparative genomic hybridization, performing comprehensive chromosome analysis to assess both cells of the two-cell stage in vitro porcine embryos. We thus described the incidence, nature and origin of chromosome abnormalities, i.e. whether they derived from incorrect meiotic division during gametogenesis or aberrant mitotic division in the zygote. We observed that 19 out of 51 (37%) of two-cell stage early pig IVP embryos had a chromosome abnormality, mostly originating from an abnormal division in the zygote. Moreover, we frequently encountered multiple aneuploidies and segmental chromosome aberrations. These results indicate that the pig may be particularly sensitive to in vitro production, which may, in turn, be due to incorrect chromosome segregations during meiosis and early cleavage divisions. We thus accept our hypothesis that chromosome abnormality could explain poor IVP outcomes in pigs.
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Fernández SF, Toro E, Colomar A, López-Teijón M, Velilla E. A 24-chromosome FISH technique in preimplantation genetic diagnosis: validation of the method. Syst Biol Reprod Med 2015; 61:171-7. [PMID: 25582218 DOI: 10.3109/19396368.2014.1002869] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Embryo screening for aneuploidy (AS) is part of preimplantation genetic diagnostics (PGD) and is aimed at improving the efficiency of assisted reproduction. Currently, several technologies, including the well-established fluorescence in situ hybridization (FISH) technique, cover the screening of all chromosomes in a single cell. This study evaluates a novel 24-chromosome FISH technique protocol (FISH-24). A total of 337 embryos were analyzed using the traditional 9-chromosome FISH technique (FISH-9) while 251 embryos were evaluated using the new FISH-24 technique. Embryos deemed nontransferable on Day 3 were cultured in vitro to Day 5 of development, then fixed and reanalyzed according to the technique allocated to each treatment cycle (107 embryos analyzed by FISH-9 and 111 by FISH-24). The global error rate (discrepancy between Day 3 and Day 5 results for a single embryo) was 2.8% after FISH-9 and 3.6% after FISH-24, with a p value of 0.95. Thus, we have established and validated a 24-chromosome FISH-based single cell aneuploidy screening technique, showing that the error rate obtained for FISH-24 is independent of the number of chromosomes analyzed and equivalent to the error rate observed for FISH-9, as a useful tool for chromosome segregation studies and clinical use.
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17
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Meiotic Nondisjunction: Insights into the Origin and Significance of Aneuploidy in Human Spermatozoa. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 868:1-21. [DOI: 10.1007/978-3-319-18881-2_1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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18
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Chow JFC, Yeung WSB, Lau EYL, Lee VCY, Ng EHY, Ho PC. Array comparative genomic hybridization analyses of all blastomeres of a cohort of embryos from young IVF patients revealed significant contribution of mitotic errors to embryo mosaicism at the cleavage stage. Reprod Biol Endocrinol 2014; 12:105. [PMID: 25420429 PMCID: PMC4256731 DOI: 10.1186/1477-7827-12-105] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 09/01/2014] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Embryos produced by in vitro fertilization (IVF) have a high level of aneuploidy, which is believed to be a major factor affecting the success of human assisted reproduction treatment. The aneuploidy rate of cleavage stage embryos based on 1-2 biopsied blastomeres has been well-reported, however, the true aneuploidy rate of whole embryos remain unclear because of embryo mosaicism. To study the prevalence of mosaicism in top quality IVF embryos, surplus embryos donated from young patients (aged 28-32) in the assisted reproduction program at Queen Mary Hospital, Hong Kong were used. METHODS Thirty-six good quality day 2 embryos were thawed. Out of the 135 blastomeres in these embryos, 121 (89.6%) survived thawing. Twelve of these embryos without lysed blastomeres and which cleaved to at least seven cells after a 24-h culture were dissembled into individual blastomeres, which were analysed by array comparative genomic hybridization and microsatellite marker analysis by fluorescent PCR. RESULTS Out of 12 day-3 embryos, 2 (16.7%) were normal, 3 (25%) were diploid/aneuploidy with <38% abnormality, 4 (33.3%) were diploid/aneuploidy mosaic with > =38% abnormality, and three (25%) were mosaic aneuploids. Conclusive chromosomal data were obtained from a high percentage of blastomeres (92.8%, 90/97). Microsatellite marker analysis performed on blastomeres in aneuploid embryos enabled us to reconstruct the chromosomal status of the blastomeres in each cleavage division. The results showed the occurrence of meiotic errors in 3 (25%) of the studied embryos. There were 16 mitotic errors (18.8%, 16/85) in the 85 mitotic divisions undertaken by the studied embryos. The observed mitotic errors were mainly contributed by endoreduplication (31.3%, 5/16), non-disjunction (25%, 4/16) and anaphase lagging (25%, 4/16). Chromosome breakages occurred in 6 divisions (7.1%, 6/85). CONCLUSIONS Mosaicism occurs in a high percentage of good-quality cleavage stage embryos and mitotic errors contribute significantly to the abnormality.
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Affiliation(s)
- Judy FC Chow
- Department of Obstetrics and Gynaecology, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong
| | - William SB Yeung
- Department of Obstetrics and Gynaecology, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong
| | - Estella YL Lau
- Department of Obstetrics and Gynaecology, Queen Mary Hospital, Pokfulam, Hong Kong
| | - Vivian CY Lee
- Department of Obstetrics and Gynaecology, Queen Mary Hospital, Pokfulam, Hong Kong
| | - Ernest HY Ng
- Department of Obstetrics and Gynaecology, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong
| | - Pak-Chung Ho
- Department of Obstetrics and Gynaecology, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong
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19
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Taylor TH, Gitlin SA, Patrick JL, Crain JL, Wilson JM, Griffin DK. The origin, mechanisms, incidence and clinical consequences of chromosomal mosaicism in humans. Hum Reprod Update 2014; 20:571-81. [PMID: 24667481 DOI: 10.1093/humupd/dmu016] [Citation(s) in RCA: 244] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Chromosomal mosaicism, the presence of two or more distinct cell lines, is prevalent throughout human pre- and post-implantation development and can lead to genetic abnormalities, miscarriages, stillbirths or live births. Due to the prevalence and significance of mosaicism in the human species, it is important to understand the origins, mechanisms and incidence of mosaicism throughout development. METHODS Literature searches were conducted utilizing Pubmed, with emphasis on human pre- and post-implantation mosaicism. RESULTS Mosaicism persists in two separate forms: general and confined. General mosaicism is routine during human embryonic growth as detected by preimplantation genetic screening at either the cleavage or blastocyst stage, leading to mosaicism within both the placenta and fetus proper. Confined mosaicism has been reported in the brain, gonads and placenta, amongst other places. Mosaicism is derived from a variety of mechanisms including chromosome non-disjunction, anaphase lagging or endoreplication. Anaphase lagging has been implicated as the main process by which mosaicism arises in the preimplantation embryo. Furthermore, mosaicism can be caused by any one of numerous factors from paternal, maternal or exogenous factors such as culture media or possibly controlled ovarian hyperstimulation during in vitro fertilization (IVF). Mosaicism has been reported in as high as 70 and 90% of cleavage- and blastocyst-stage embryos derived from IVF, respectively. CONCLUSIONS The clinical consequences of mosaicism depend on which chromosome is involved, and when and where an error occurs. Mitotic rescue of a meiotic error or a very early mitotic error will typically lead to general mosaicism while a mitotic error at a specific cell lineage point typically leads to confined mosaicism. The clinical consequences of mosaicism are dependent on numerous aspects, with the consequences being unique for each event.
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Affiliation(s)
- Tyl H Taylor
- Reproductive Endocrinology Associates of Charlotte, 1524 E Morehead St., Charlotte, 28207 NC, USA Department of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
| | - Susan A Gitlin
- Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Jones Institute for Reproductive Medicine, 601 Colley Avenue #316, Norfolk, 23507 VA, USA
| | - Jennifer L Patrick
- Reproductive Endocrinology Associates of Charlotte, 1524 E Morehead St., Charlotte, 28207 NC, USA
| | - Jack L Crain
- Reproductive Endocrinology Associates of Charlotte, 1524 E Morehead St., Charlotte, 28207 NC, USA
| | - J Michael Wilson
- Reproductive Endocrinology Associates of Charlotte, 1524 E Morehead St., Charlotte, 28207 NC, USA
| | - Darren K Griffin
- Department of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
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20
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Handyside AH. 24-chromosome copy number analysis: a comparison of available technologies. Fertil Steril 2013; 100:595-602. [DOI: 10.1016/j.fertnstert.2013.07.1965] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 07/08/2013] [Accepted: 07/15/2013] [Indexed: 12/21/2022]
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21
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Hierarchical radial and polar organisation of chromosomes in human sperm. Chromosome Res 2012; 20:875-87. [DOI: 10.1007/s10577-012-9323-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Revised: 10/29/2012] [Accepted: 10/31/2012] [Indexed: 01/06/2023]
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