The incidence and origin of segmental aneuploidy in human oocytes and preimplantation embryos

Babariya, D; Fragouli, Elpida; Alfarawati, S; Spath, K; Wells, Dagan

doi:10.1093/humrep/dex324

Cited by 110 publications

(97 citation statements)

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“…In addition to chromosome size, gene density may also play a role. For example, even though chromosomes 18 and 19 are similar in size, they differ dramatically in gene density (Boyle et al 2001, Babariya et al 2017. Chromosome 19 is one of the most gene-rich chromosomes, whereas chromosome 18 is one of the gene poorest chromosomes.…”

Section: Lessons Learned From Meiotic Prophase I Studiesmentioning

confidence: 99%

Meiotic nondisjunction and sperm aneuploidy in humans

2018

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Infertility is relatively common affecting approximately 1-in-6 couples. Although the genetic basis of infertility is increasingly being uncovered, the contribution of male infertility often remains unexplained. The leading cause of pregnancy loss and cognitive impairment in humans is chromosome aneuploidy. Sperm aneuploidy is routinely evaluated by fluorescence in situ hybridization. The majority of studies have reported similar findings, namely: (1) all men produce aneuploid sperm; (2) certain chromosomes are more prone to undergo chromosome nondisjunction; (3) infertile men typically have significantly higher levels of sperm aneuploidy compared to controls and (4) the level of aneuploidy is often correlated with the severity of the infertility. Despite this, sperm aneuploidy screening is rarely evaluated in the infertility clinic. Within recent years, there appears to be renewed interest in the clinical relevance of sperm aneuploidy. We shall examine the gender differences in meiosis between the sexes and explore why less emphasis is placed on the paternal contribution to aneuploidy. Increased sperm aneuploidy is often perceived to be modest and not clinically relevant, compared to the female contribution. However, even small increases in sperm aneuploidy may impact fertility and IVF cycle outcomes. Evidence demonstrating the clinical relevance of sperm aneuploidy will be discussed, as well as some of the challenges precluding widespread clinical implementation. Technological developments that may lead to widespread clinical implementation will be discussed. Recommendations will be suggested for specific patient groups that may benefit from sperm aneuploidy screening and whether preimplantation genetic testing for aneuploidy should be discussed with these patients.

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Section: Lessons Learned From Meiotic Prophase I Studiesmentioning

confidence: 99%

Meiotic nondisjunction and sperm aneuploidy in humans

2018

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“…This does not exclude cases where both blastomeres are not totipotent and the embryo is, therefore, unviable. This can be due to the failure of both blastomeres reflecting errors of chromosome segregation at first zygotic mitosis (most aneuploidies preclude development to term; Rabinowitz et al 2012, Babariya et al 2017 or the lack of developmental competence of some oocytes, i.e. not all of them developed after fertilization because of a deficiency in maternal factors (Christians 2017).…”

Section: Conclusion and Revised Model: Mosaic Construction Of Zygotimentioning

confidence: 99%

Totipotency continuity from zygote to early blastomeres: a model under revision

et al. 2019

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The mammalian zygote is a totipotent cell that generates all the cells of a new organism through embryonic development. However, if one asks about the totipotency of blastomeres after one or two zygotic divisions, opinions differ. As it is impossible to determine the individual developmental potency of early blastomeres in an intact embryo, experiments of blastomere isolation were conducted in various species, showing that two-cell blastomeres could give rise to a new organism when sister cells were separated. A mainstream interpretation was that each of the sister mammalian blastomeres was equally totipotent. However, reevaluation of those experiments raised some doubts about the real prevalence of cases in which this interpretation could truly be validated. We compiled experiments that tested the individual developmental potency of early mammalian blastomeres in a cell-autonomous way (i.e. excluding nuclear transfer and chimera production). We then confronted the developmental abilities with reported molecular differences between sister blastomeres. The reevaluated observations were at odds with the mainstream view: A viable two-cell embryo can already include one non-totipotent blastomere. We were, thus, led to propose a revised model for totipotency continuity based on the construction of the zygote as a mosaic, which accounts for differential inheritance of totipotency-relevant components between sister blastomeres. This takes place with no preordained mechanisms that would ensure a reproducible partition. This model, which is compatible with the body of data on regulative properties of mammalian early embryos, aims at tempering the rigid interpretation that discounted maternal constraints on totipotency.Reproduction (2019) 158 R49-R65

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“…The use of molecular comprehensive cytogenetic methods, such as comparative genomic hybridization (metaphase or array), has provided a wealth of information on the chromosome constitution of oocytes and their polar bodies (4,5). A potential consequence of DNA damage is the generation of double-strand breaks, which would in turn lead to duplications or deletions affecting parts of chromosomes.…”

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confidence: 99%

“…A potential consequence of DNA damage is the generation of double-strand breaks, which would in turn lead to duplications or deletions affecting parts of chromosomes. Partial chromosome abnormalities, also known as segmental aneuploidies, have frequently been observed in oocytes and embryos (4,5). A recent investigation of the incidence of segmental chromosome errors determined that 10% of oocytes carry such aneuploidies after both meiotic divisions have been completed (5).…”

mentioning

confidence: 99%

“…Partial chromosome abnormalities, also known as segmental aneuploidies, have frequently been observed in oocytes and embryos (4,5). A recent investigation of the incidence of segmental chromosome errors determined that 10% of oocytes carry such aneuploidies after both meiotic divisions have been completed (5). These findings are indicative of DNA damage occurring during oocyte ovarian maturation and a possible lack of SAC activity.…”

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confidence: 99%

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