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Journal articles on the topic 'Chromosomal rearrangements'
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1
Schoen, Daniel J. "Comparative Genomics, Marker Density and Statistical Analysis of Chromosome Rearrangements." Genetics 154, no. 2 (February 1, 2000): 943–52. http://dx.doi.org/10.1093/genetics/154.2.943.
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Abstract Estimates of the number of chromosomal breakpoints that have arisen (e.g., by translocation and inversion) in the evolutionary past between two species and their common ancestor can be made by comparing map positions of marker loci. Statistical methods for doing so are based on a random-breakage model of chromosomal rearrangement. The model treats all modes of chromosome rearrangement alike, and it assumes that chromosome boundaries and breakpoints are distributed randomly along a single genomic interval. Here we use simulation and numerical analysis to test the validity of these model assumptions. Mean estimates of numbers of breakpoints are close to those expected under the random-breakage model when marker density is high relative to the amount of chromosomal rearrangement and when rearrangements occur by translocation alone. But when marker density is low relative to the number of chromosomes, and when rearrangements occur by both translocation and inversion, the number of breakpoints is underestimated. The underestimate arises because rearranged segments may contain markers, yet the rearranged segments may, nevertheless, be undetected. Variances of the estimate of numbers of breakpoints decrease rapidly as markers are added to the comparative maps, but are less influenced by the number or type of chromosomal rearrangement separating the species. Variances obtained with simulated genomes comprised of chromosomes of equal length are substantially lower than those obtained when chromosome size is unconstrained. Statistical power for detecting heterogeneity in the rate of chromosomal rearrangement is also investigated. Results are interpreted with respect to the amount of marker information required to make accurate inferences about chromosomal evolution.
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Donaldson, Brendan, Daniel A. F. Villagomez, Tamas Revay, Samira Rezaei, and W. Allan King. "Non-Random Distribution of Reciprocal Translocation Breakpoints in the Pig Genome." Genes 10, no. 10 (September 30, 2019): 769. http://dx.doi.org/10.3390/genes10100769.
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Balanced chromosome rearrangements are one of the main etiological factors contributing to hypoprolificacy in the domestic pig. Amongst domestic animals, the pig is considered to have the highest prevalence of chromosome rearrangements. To date over 200 unique chromosome rearrangements have been identified. The factors predisposing pigs to chromosome rearrangements, however, remain poorly understood. Nevertheless, here we provide empirical evidence which sustains the notion that there is a non-random distribution of chromosomal rearrangement breakpoints in the pig genome. We sought to establish if there are structural chromosome factors near which rearrangement breakpoints preferentially occur. The distribution of rearrangement breakpoints was analyzed across three level, chromosomes, chromosome arms, and cytogenetic GTG-bands (G-banding using trypsin and giemsa). The frequency of illegitimate exchanges (e.g., reciprocal translocations) between individual chromosomes and chromosome arms appeared to be independent of chromosome length and centromere position. Meanwhile chromosome breakpoints were overrepresented on some specific G-bands, defining chromosome hotspots for ectopic exchanges. Cytogenetic band level factors, such as the length of bands, chromatin density, and presence of fragile sites, were associated with the presence of translocation breakpoints. The characteristics of these bands were largely similar to that of hotspots in the human genome. Therefore, those hotspots are proposed as a starting point for future molecular analyses into the genomic landscape of porcine chromosome rearrangements.
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Ostevik, Kate L., Kieran Samuk, and Loren H. Rieseberg. "Ancestral Reconstruction of Karyotypes Reveals an Exceptional Rate of Nonrandom Chromosomal Evolution in Sunflower." Genetics 214, no. 4 (February 7, 2020): 1031–45. http://dx.doi.org/10.1534/genetics.120.303026.
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Mapping the chromosomal rearrangements between species can inform our understanding of genome evolution, reproductive isolation, and speciation. Here, we present a novel algorithm for identifying regions of synteny in pairs of genetic maps, which is implemented in the accompanying R package syntR. The syntR algorithm performs as well as previous ad hoc methods while being systematic, repeatable, and applicable to mapping chromosomal rearrangements in any group of species. In addition, we present a systematic survey of chromosomal rearrangements in the annual sunflowers, which is a group known for extreme karyotypic diversity. We build high-density genetic maps for two subspecies of the prairie sunflower, Helianthus petiolaris ssp. petiolaris and H. petiolaris ssp. fallax. Using syntR, we identify blocks of synteny between these two subspecies and previously published high-density genetic maps. We reconstruct ancestral karyotypes for annual sunflowers using those synteny blocks and conservatively estimate that there have been 7.9 chromosomal rearrangements per million years, a high rate of chromosomal evolution. Although the rate of inversion is even higher than the rate of translocation in this group, we further find that every extant karyotype is distinguished by between one and three translocations involving only 8 of the 17 chromosomes. This nonrandom exchange suggests that specific chromosomes are prone to translocation and may thus contribute disproportionately to widespread hybrid sterility in sunflowers. These data deepen our understanding of chromosome evolution and confirm that Helianthus has an exceptional rate of chromosomal rearrangement that may facilitate similarly rapid diversification.
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Stern, MH, S. Lipkowitz, A. Aurias, C. Griscelli, G. Thomas, and IR Kirsch. "Inversion of chromosome 7 in ataxia telangiectasia is generated by a rearrangement between T-cell receptor beta and T-cell receptor gamma genes." Blood 74, no. 6 (November 1, 1989): 2076–80. http://dx.doi.org/10.1182/blood.v74.6.2076.2076.
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Abstract Specific and recurrent chromosomal rearrangements are often observed in the karyotypes of phytohemagglutinin-stimulated lymphocytes. The percentage of cells demonstrating these rearrangements is dramatically increased in the genetic disease ataxia telangiectasia. Inversion of chromosome 7 represents approximately half of the chromosomal rearrangements in this disease. Because the chromosomal locations of the inv(7) breakpoints coincide precisely with those of the T-cell antigen receptor (TCR) beta and gamma genes, it has been hypothesized that this rearrangement may occur by recombination between those two loci. Here, we present direct evidence that inversion of chromosome 7 in ataxia telangiectasia is generated by site-specific recombination between a TCR gamma variable segment and a TCR beta joining segment.
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Stern, MH, S. Lipkowitz, A. Aurias, C. Griscelli, G. Thomas, and IR Kirsch. "Inversion of chromosome 7 in ataxia telangiectasia is generated by a rearrangement between T-cell receptor beta and T-cell receptor gamma genes." Blood 74, no. 6 (November 1, 1989): 2076–80. http://dx.doi.org/10.1182/blood.v74.6.2076.bloodjournal7462076.
Full textAbstract:
Specific and recurrent chromosomal rearrangements are often observed in the karyotypes of phytohemagglutinin-stimulated lymphocytes. The percentage of cells demonstrating these rearrangements is dramatically increased in the genetic disease ataxia telangiectasia. Inversion of chromosome 7 represents approximately half of the chromosomal rearrangements in this disease. Because the chromosomal locations of the inv(7) breakpoints coincide precisely with those of the T-cell antigen receptor (TCR) beta and gamma genes, it has been hypothesized that this rearrangement may occur by recombination between those two loci. Here, we present direct evidence that inversion of chromosome 7 in ataxia telangiectasia is generated by site-specific recombination between a TCR gamma variable segment and a TCR beta joining segment.
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Villa, Nicoletta, Serena Redaelli, Stefania Farina, Donatella Conconi, Elena Maria Sala, Francesca Crosti, Silvana Mariani, et al. "Genomic Complexity and Complex Chromosomal Rearrangements in Genetic Diagnosis: Two Illustrative Cases on Chromosome 7." Genes 14, no. 9 (August 27, 2023): 1700. http://dx.doi.org/10.3390/genes14091700.
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Complex chromosomal rearrangements are rare events compatible with survival, consisting of an imbalance and/or position effect of one or more genes, that contribute to a range of clinical presentations. The investigation and diagnosis of these cases are often difficult. The interpretation of the pattern of pairing and segregation of these chromosomes during meiosis is important for the assessment of the risk and the type of imbalance in the offspring. Here, we investigated two unrelated pediatric carriers of complex rearrangements of chromosome 7. The first case was a 2-year-old girl with a severe phenotype. Conventional cytogenetics evidenced a duplication of part of the short arm of chromosome 7. By array-CGH analysis, we found a complex rearrangement with three discontinuous trisomy regions (7p22.1p21.3, 7p21.3, and 7p21.3p15.3). The second case was a newborn investigated for hypodevelopment and dimorphisms. The karyotype analysis promptly revealed a structurally altered chromosome 7. The array-CGH analysis identified an even more complex rearrangement consisting of a trisomic region at 7q11.23q22 and a tetrasomic region of 4.5 Mb spanning 7q21.3 to q22.1. The mother’s karyotype examination revealed a complex rearrangement of chromosome 7: the 7q11.23q22 region was inserted in the short arm at 7p15.3. Finally, array-CGH analysis showed a trisomic region that corresponds to the tetrasomic region of the son. Our work proved that the integration of several technical solutions is often required to appropriately analyze complex chromosomal rearrangements in order to understand their implications and offer appropriate genetic counseling.
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Xie, Songlin, Nadeem Khan, M. S. Ramanna, Lixin Niu, Agnieszka Marasek-Ciolakowska, Paul Arens, and Jaap M. van Tuyl. "An assessment of chromosomal rearrangements in neopolyploids of Lilium hybrids." Genome 53, no. 6 (June 2010): 439–46. http://dx.doi.org/10.1139/g10-018.
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Two types of newly induced polyploids (neopolyploids) of Lilium hybrids were monitored for the occurrence of chromosomal rearrangements through genomic in situ hybridization (GISH) technique. One of the populations was obtained through crossing an allotriploid Longiflorum × Oriental hybrid (LLO) with an allotetraploid Longiflorum × Trumpet hybrid (LLTT), both of which were derived from somatic chromosome doubling. The other type of allopolyploid population was derived from meiotic chromosome doubling in which numerically unreduced (2n) gametes from two different interspecific hybrids, namely, Longiflorum × Asiatic (LA) and Oriental × Asiatic (OA), were used to get backcross progeny with the Asiatic parents. GISH clearly discriminated the three constituent genomes (L, T, and O) in the complements of the progeny obtained from mitotic chromosome doubling. A total of 26 individuals were analyzed from this population and there was no evidence of chromosomal rearrangements. However, in the case of meiotically doubled allopolyploid progeny, considerable frequencies of chromosomal rearrangements were observed through GISH. The so-called chromosomal rearrangements in meiotic polyploids are the result of homoeologous recombination rather than translocations. Furthermore, evidence for the occurrence of meiotic recombination in the LA hybrids has been confirmed with GISH on meiotic chromosomes. Thus, there was evidence that neopolyploids of Lilium hybrids did not possess any noticeable chromosome rearrangements.
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Marder, B. A., and W. F. Morgan. "Delayed chromosomal instability induced by DNA damage." Molecular and Cellular Biology 13, no. 11 (November 1993): 6667–77. http://dx.doi.org/10.1128/mcb.13.11.6667-6677.1993.
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DNA damage induced by ionizing radiation can result in gene mutation, gene amplification, chromosome rearrangements, cellular transformation, and cell death. Although many of these changes may be induced directly by the radiation, there is accumulating evidence for delayed genomic instability following X-ray exposure. We have investigated this phenomenon by studying delayed chromosomal instability in a hamster-human hybrid cell line by means of fluorescence in situ hybridization. We examined populations of metaphase cells several generations after expanding single-cell colonies that had survived 5 or 10 Gy of X rays. Delayed chromosomal instability, manifested as multiple rearrangements of human chromosome 4 in a background of hamster chromosomes, was observed in 29% of colonies surviving 5 Gy and in 62% of colonies surviving 10 Gy. A correlation of delayed chromosomal instability with delayed reproductive cell death, manifested as reduced plating efficiency in surviving clones, suggests a role for chromosome rearrangements in cytotoxicity. There were small differences in chromosome destabilization and plating efficiencies between cells irradiated with 5 or 10 Gy of X rays after a previous exposure to 10 Gy and cells irradiated only once. Cell clones showing delayed chromosomal instability had normal frequencies of sister chromatid exchange formation, indicating that at this cytogenetic endpoint the chromosomal instability was not apparent. The types of chromosomal rearrangements observed suggest that chromosome fusion, followed by bridge breakage and refusion, contributes to the observed delayed chromosomal instability.
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Marder, B. A., and W. F. Morgan. "Delayed chromosomal instability induced by DNA damage." Molecular and Cellular Biology 13, no. 11 (November 1993): 6667–77. http://dx.doi.org/10.1128/mcb.13.11.6667.
Full textAbstract:
DNA damage induced by ionizing radiation can result in gene mutation, gene amplification, chromosome rearrangements, cellular transformation, and cell death. Although many of these changes may be induced directly by the radiation, there is accumulating evidence for delayed genomic instability following X-ray exposure. We have investigated this phenomenon by studying delayed chromosomal instability in a hamster-human hybrid cell line by means of fluorescence in situ hybridization. We examined populations of metaphase cells several generations after expanding single-cell colonies that had survived 5 or 10 Gy of X rays. Delayed chromosomal instability, manifested as multiple rearrangements of human chromosome 4 in a background of hamster chromosomes, was observed in 29% of colonies surviving 5 Gy and in 62% of colonies surviving 10 Gy. A correlation of delayed chromosomal instability with delayed reproductive cell death, manifested as reduced plating efficiency in surviving clones, suggests a role for chromosome rearrangements in cytotoxicity. There were small differences in chromosome destabilization and plating efficiencies between cells irradiated with 5 or 10 Gy of X rays after a previous exposure to 10 Gy and cells irradiated only once. Cell clones showing delayed chromosomal instability had normal frequencies of sister chromatid exchange formation, indicating that at this cytogenetic endpoint the chromosomal instability was not apparent. The types of chromosomal rearrangements observed suggest that chromosome fusion, followed by bridge breakage and refusion, contributes to the observed delayed chromosomal instability.
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Swenson, Krister M., and Mathieu Blanchette. "Large-scale mammalian genome rearrangements coincide with chromatin interactions." Bioinformatics 35, no. 14 (July 2019): i117—i126. http://dx.doi.org/10.1093/bioinformatics/btz343.
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Abstract Motivation Genome rearrangements drastically change gene order along great stretches of a chromosome. There has been initial evidence that these apparently non-local events in the 1D sense may have breakpoints that are close in the 3D sense. We harness the power of the Double Cut and Join model of genome rearrangement, along with Hi-C chromosome conformation capture data to test this hypothesis between human and mouse. Results We devise novel statistical tests that show that indeed, rearrangement scenarios that transform the human into the mouse gene order are enriched for pairs of breakpoints that have frequent chromosome interactions. This is observed for both intra-chromosomal breakpoint pairs, as well as for inter-chromosomal pairs. For intra-chromosomal rearrangements, the enrichment exists from close (<20 Mb) to very distant (100 Mb) pairs. Further, the pattern exists across multiple cell lines in Hi-C data produced by different laboratories and at different stages of the cell cycle. We show that similarities in the contact frequencies between these many experiments contribute to the enrichment. We conclude that either (i) rearrangements usually involve breakpoints that are spatially close or (ii) there is selection against rearrangements that act on spatially distant breakpoints. Availability and implementation Our pipeline is freely available at https://bitbucket.org/thekswenson/locality. Supplementary information Supplementary data are available at Bioinformatics online.
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Zheng, Binhai, Marijke Sage, Elizabeth A. Sheppeard, Vesna Jurecic, and Allan Bradley. "Engineering Mouse Chromosomes with Cre-loxP: Range, Efficiency, and Somatic Applications." Molecular and Cellular Biology 20, no. 2 (January 15, 2000): 648–55. http://dx.doi.org/10.1128/mcb.20.2.648-655.2000.
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ABSTRACT Chromosomal rearrangements are important resources for genetic studies. Recently, a Cre-loxP-based method to introduce defined chromosomal rearrangements (deletions, duplications, and inversions) into the mouse genome (chromosome engineering) has been established. To explore the limits of this technology systematically, we have evaluated this strategy on mouse chromosome 11. Although the efficiency of Cre-loxP-mediated recombination decreases with increasing genetic distance when the two endpoints are on the same chromosome, the efficiency is not limiting even when the genetic distance is maximized. Rearrangements encompassing up to three quarters of chromosome 11 have been constructed in mouse embryonic stem (ES) cells. While larger deletions may lead to ES cell lethality, smaller deletions can be produced very efficiently both in ES cells and in vivo in a tissue- or cell-type-specific manner. We conclude that any chromosomal rearrangement can be made in ES cells with the Cre-loxP strategy provided that it does not affect cell viability. In vivo chromosome engineering can be potentially used to achieve somatic losses of heterozygosity in creating mouse models of human cancers.
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Hieber, Ludwig, Reinhard Huber, Verena Bauer, Quirin Schäffner, Herbert Braselmann, Geraldine Thomas, Tatjana Bogdanova, and Horst Zitzelsberger. "Chromosomal Rearrangements in Post-Chernobyl Papillary Thyroid Carcinomas: Evaluation by Spectral Karyotyping and Automated Interphase FISH." Journal of Biomedicine and Biotechnology 2011 (2011): 1–7. http://dx.doi.org/10.1155/2011/693691.
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Structural genomic rearrangements are frequent findings in human cancers. Therefore, papillary thyroid carcinomas (PTCs) were investigated for chromosomal aberrations and rearrangements of the RET proto-oncogene. For this purpose, primary cultures from 23 PTC have been established and metaphase preparations were analysed by spectral karyotyping (SKY). In addition, interphase cell preparations of the same cases were investigated by fluorescencein situhybridisation (FISH) for the presence of RET/PTC rearrangements using RET-specific DNA probes. SKY analysis of PTC revealed structural aberrations of chromosome 11 and several numerical aberrations with frequent loss of chromosomes 20, 21, and 22. FISH analysis for RET/PTC rearrangements showed prevalence of this rearrangement in 72% (16 out of 22) of cases. However, only subpopulations of tumour cells exhibited this rearrangement indicating genetic heterogeneity. The comparison of visual and automated scoring of FISH signals revealed concordant results in 19 out of 22 cases (87%) indicating reliable scoring results using the optimised scoring parameter for RET/PTC with the automated Metafer4 system. It can be concluded from this study that genomic rearrangements are frequent in PTC and therefore important events in thyroid carcinogenesis.
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Kartapradja, Hannie, Nanis Sacharina Marzuki, Mark D. Pertile, David Francis, Lita Putri Suciati, Helena Woro Anggaratri, Debby Dwi Ambarwati, et al. "Exceptional Complex Chromosomal Rearrangements in Three Generations." Case Reports in Genetics 2015 (2015): 1–5. http://dx.doi.org/10.1155/2015/321014.
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We report an exceptional complex chromosomal rearrangement (CCR) found in three individuals in a family that involves 4 chromosomes with 5 breakpoints. The CCR was ascertained in a phenotypically abnormal newborn with additional chromosomal material on the short arm of chromosome 4. Maternal karyotyping indicated that the mother carried an apparently balanced CCR involving chromosomes 4, 6, 11, and 18. Maternal transmission of the derivative chromosome 4 resulted in partial trisomy for chromosomes 6q and 18q and a partial monosomy of chromosome 4p in the proband. Further family studies found that the maternal grandmother carried the same apparently balanced CCR as the proband’s mother, which was confirmed using the whole chromosome painting (WCP) FISH. High resolution whole genome microarray analysis of DNA from the proband’s mother found no evidence for copy number imbalance in the vicinity of the CCR translocation breakpoints, or elsewhere in the genome, providing evidence that the mother’s and grandmother’s CCRs were balanced at a molecular level. This structural rearrangement can be categorized as an exceptional CCR due to its complexity and is a rare example of an exceptional CCR being transmitted in balanced and/or unbalanced form across three generations.
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Yen, Jui-Hung, Shao-Yin Chu, Yann-Jang Chen, Yi-Chieh Su, Chun-Ching Chien, Chun-Ying Weng, and Pei-Yi Chen. "A Maternally Inherited Rare Case with Chromoanagenesis-Related Complex Chromosomal Rearrangements and De Novo Microdeletions." Diagnostics 12, no. 8 (August 5, 2022): 1900. http://dx.doi.org/10.3390/diagnostics12081900.
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Chromoanagenesis is a phenomenon of highly complex rearrangements involving the massive genomic shattering and reconstitution of chromosomes that has had a great impact on cancer biology and congenital anomalies. Complex chromosomal rearrangements (CCRs) are structural alterations involving three or more chromosomal breakpoints between at least two chromosomes. Here, we present a 3-year-old boy exhibiting multiple congenital malformations and developmental delay. The cytogenetic analysis found a highly complex CCR inherited from the mother involving four chromosomes and five breakpoints due to forming four derivative chromosomes (2, 3, 6 and 11). FISH analysis identified an ultrarare derivative chromosome 11 containing three parts that connected the 11q telomere to partial 6q and 3q fragments. We postulate that this derivative chromosome 11 is associated with chromoanagenesis-like phenomena by which DNA repair can result in a cooccurrence of inter-chromosomal translocations. Additionally, chromosome microarray studies revealed that the child has one subtle maternal-inherited deletion at 6p12.1 and two de novo deletions at 6q14.1 and 6q16.1~6q16.3. Here, we present a familial CCR case with rare rearranged chromosomal structures and the use of multiple molecular techniques to delineate these genomic alterations. We suggest that chromoanagenesis may be a possible mechanism involved in the repair and reconstitution of these rearrangements with evidence for increasing genomic imbalances such as additional deletions in this case.
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Lukhtanov, Vladimir A., Vlad Dincă, Magne Friberg, Jindra Šíchová, Martin Olofsson, Roger Vila, František Marec, and Christer Wiklund. "Versatility of multivalent orientation, inverted meiosis, and rescued fitness in holocentric chromosomal hybrids." Proceedings of the National Academy of Sciences 115, no. 41 (September 28, 2018): E9610—E9619. http://dx.doi.org/10.1073/pnas.1802610115.
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Chromosomal rearrangements (e.g., fusions/fissions) have the potential to drive speciation. However, their accumulation in a population is generally viewed as unlikely, because chromosomal heterozygosity should lead to meiotic problems and aneuploid gametes. Canonical meiosis involves segregation of homologous chromosomes in meiosis I and sister chromatid segregation during meiosis II. In organisms with holocentric chromosomes, which are characterized by kinetic activity distributed along almost the entire chromosome length, this order may be inverted depending on their metaphase I orientation. Here we analyzed the evolutionary role of this intrinsic versatility of holocentric chromosomes, which is not available to monocentric ones, by studying F1 to F4 hybrids between two chromosomal races of the Wood White butterfly (Leptidea sinapis), separated by at least 24 chromosomal fusions/fissions. We found that these chromosomal rearrangements resulted in multiple meiotic multivalents, and, contrary to the theoretical prediction, the hybrids displayed relatively high reproductive fitness (42% of that of the control lines) and regular behavior of meiotic chromosomes. In the hybrids, we also discovered inverted meiosis, in which the first and critical stage of chromosome number reduction was replaced by the less risky stage of sister chromatid separation. We hypothesize that the ability to invert the order of the main meiotic events facilitates proper chromosome segregation and hence rescues fertility and viability in chromosomal hybrids, potentially promoting dynamic karyotype evolution and chromosomal speciation.
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Zhang, Jianbo, and Thomas Peterson. "Genome Rearrangements by Nonlinear Transposons in Maize." Genetics 153, no. 3 (November 1, 1999): 1403–10. http://dx.doi.org/10.1093/genetics/153.3.1403.
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Abstract Transposable elements have long been considered as potential agents of large-scale genome reorganization by virtue of their ability to induce chromosomal rearrangements such as deletions, duplications, inversions, and reciprocal translocations. Previous researchers have shown that particular configurations of transposon termini can induce chromosome rearrangements at high frequencies. Here, we have analyzed chromosomal rearrangements derived from an unstable allele of the maize P1 (pericarp color) gene. The progenitor allele contains both a full-length Ac (Activator) transposable element and an Ac terminal fragment termed fAc (fractured Ac) inserted in the second intron of the P1-rr gene. Two rearranged alleles were derived from a classical maize ear twinned sector and were found to contain a large inverted duplication and a corresponding deficiency. The sequences at the junctions of the rearrangement breakpoints indicate that the duplication and deletion structures were produced by a single transposition event involving Ac and fAc termini located on sister chromatids. Because the transposition process we describe involves transposon ends located on different DNA molecules, it is termed nonlinear transposition (NLT). NLT can rapidly break and rejoin chromosomes and thus could have played an important role in generating structural heterogeneity during genome evolution.
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Tang, Xing-Xing, Xue-Ping Wen, Lei Qi, Yang Sui, Ying-Xuan Zhu, and Dao-Qiong Zheng. "Origin, Regulation, and Fitness Effect of Chromosomal Rearrangements in the Yeast Saccharomyces cerevisiae." International Journal of Molecular Sciences 22, no. 2 (January 14, 2021): 786. http://dx.doi.org/10.3390/ijms22020786.
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Chromosomal rearrangements comprise unbalanced structural variations resulting in gain or loss of DNA copy numbers, as well as balanced events including translocation and inversion that are copy number neutral, both of which contribute to phenotypic evolution in organisms. The exquisite genetic assay and gene editing tools available for the model organism Saccharomyces cerevisiae facilitate deep exploration of the mechanisms underlying chromosomal rearrangements. We discuss here the pathways and influential factors of chromosomal rearrangements in S. cerevisiae. Several methods have been developed to generate on-demand chromosomal rearrangements and map the breakpoints of rearrangement events. Finally, we highlight the contributions of chromosomal rearrangements to drive phenotypic evolution in various S. cerevisiae strains. Given the evolutionary conservation of DNA replication and recombination in organisms, the knowledge gathered in the small genome of yeast can be extended to the genomes of higher eukaryotes.
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Ganguly, Bani Bandana, Vijay Kadam, and Nitin N. Kadam. "Clinical Expression of an Inherited Unbalanced Translocation in Chromosome 6." Case Reports in Genetics 2011 (2011): 1–6. http://dx.doi.org/10.1155/2011/396450.
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Unbalanced chromosomal rearrangements are not common; however, they have a significant clinical expression. The parental balanced translocation produces unbalanced chromosome, which is transmitted to next generation through fertilization of gametes carrying the derivative chromosome. The carriers of balanced rearrangements mostly do not have recognizable phenotypic expression. We report a family comprising of healthy and non-consanguineous young parents and their preemie newborn severely affected with congenital anomalies and systemic disorders. Conventional Gbanding analysis of somatic chromosomes identified a balanced translocation, t(6;10)(p23;q24), in mother and an unbalanced rearrangement, der(6)t(6:10)(p23;q24)mat, in the child. The child has inherited a derivative chromosome 6 with partial deletion of 6(p23-pter) and partial trisomy 10(q24-qter), which has resulted in fusion of genes of two different chromosomes. The prominent phenotypic features of del(6p), including high forehead, flat nasal bridge, agenesis of left ear, atrial septal defect (ASD), craniosynostosis, and growth retardation, are overlapping with specific Axenfeld-Reiger-, Larsen-, and Ritscher-Sinzel/3-C syndromes, however, lacking in ocular anomalies, skeletal laxity, or cerebellar malformation. Therefore, this paper rules out the isolated effect of del(6p23) or trisomy 10(q24) on distinct previously reported syndromes and proposes the combined effect of unbalanced chromosomal alteration.
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Martin, C., S. Mackay, and R. Carpenter. "Large-scale chromosomal restructuring is induced by the transposable element tam3 at the nivea locus of antirrhinum majus." Genetics 119, no. 1 (May 1, 1988): 171–84. http://dx.doi.org/10.1093/genetics/119.1.171.
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Abstract The transposable element, Tam3, gives rise to large-scale (greater than 1 kb) chromosomal rearrangements at a low frequency, when it is inserted at the nivea locus of Antirrhinum majus. Although some deletions may result from imprecise excision of Tam3, rearrangements involving deletion, dispersion and inverted duplication of flanking sequences, where Tam3 remains in situ, have also been identified. These rearrangements have been mapped at the molecular level, and the behavior of Tam3 following rearrangement has been observed. It is clear that Tam3 has enormous potential to restructure chromosomes through successive rounds of large-scale rearrangements. The mechanisms by which such rearrangements might arise are discussed.
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Unger, Kristian, Johannes Wienberg, Andrew Riches, Ludwig Hieber, Axel Walch, Andreas Brown, Patricia C. M. O'Brien, et al. "Novel gene rearrangements in transformed breast cells identified by high-resolution breakpoint analysis of chromosomal aberrations." Endocrine-Related Cancer 17, no. 1 (March 2010): 87–98. http://dx.doi.org/10.1677/erc-09-0065.
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Chromosomal copy number alterations and chromosomal rearrangements are frequent mutations in human cancer. Unlike copy number alterations, little is known about the role and occurrence of chromosomal rearrangements in breast cancer. This may be due to the fact that chromosome-based breakpoint analysis is widely restricted to cultured cells. In order to identify gene rearrangements in breast cancer, we studied the chromosomal breakpoints in radiation-transformed epithelial breast cell lines using a high-resolution array-based approach using 1 Mb bacterial artificial chromosome (BAC) arrays. The breakpoints were further narrowed down by fluorescence in situ hybridisation (FISH) with clones from the 32 k BAC library. The analysis of the cell lines B42-11 and B42-16 revealed rearrangements of chromosomes 7, 8, 10 and 12. We identified the genes Has2, Grid1, Ret, Cpm, Tbx3, Tbx5, Tuba1a, Wnt1 and Arf3 within the breakpoint regions. Quantitative RT-PCR showed a deregulated expression of all of these candidate genes except for Tbx5 and Tbx3. This is the first study demonstrating gene rearrangements and their deregulated mRNA expression in radiation-transformed breast cells. Since the gene rearrangements occurred in the transformed and tumourigenic cell lines only, it is likely that these were generated in conjunction with malignant transformation of the epithelial breast cells and therefore might reflect early molecular events in breast carcinogenesis. Initial studies indicate that these gene alterations are also found in sporadic breast cancers.
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Yu, Veronica P. C. C., Michael Koehler, Claus Steinlein, Michael Schmid, Leslyn A. Hanakahi, Alain J. van Gool, Stephen C. West, and Ashok R. Venkitaraman. "Gross chromosomal rearrangements and genetic exchange between nonhomologous chromosomes following BRCA2 inactivation." Genes & Development 14, no. 11 (June 1, 2000): 1400–1406. http://dx.doi.org/10.1101/gad.14.11.1400.
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Cancer-causing mutations often arise from gross chromosomal rearrangements (GCRs) such as translocations, which involve genetic exchange between nonhomologous chromosomes. Here we show that murineBrca2 has an essential function in suppressing GCR formation after chromosome breakage. Cells that harbor truncated Brca2spontaneously incur GCRs and genomic DNA breaks during division. They exhibit hypersensitivity to DNA damage by interstrand cross-linkers, which even at low doses trigger aberrant genetic exchange between nonhomologous chromosomes. Therefore, genetic instability in Brca2-deficient cells results from the mutagenic processing of spontaneous or induced DNA damage into gross chromosomal rearrangements, providing a mechanistic basis for cancer predisposition.
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Mirzaei, Golrokh. "GraphChrom: A Novel Graph-Based Framework for Cancer Classification Using Chromosomal Rearrangement Endpoints." Cancers 14, no. 13 (June 22, 2022): 3060. http://dx.doi.org/10.3390/cancers14133060.
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Chromosomal rearrangements are generally a consequence of improperly repaired double-strand breaks in DNA. These genomic aberrations can be a driver of cancers. Here, we investigated the use of chromosomal rearrangements for classification of cancer tumors and the effect of inter- and intrachromosomal rearrangements in cancer classification. We used data from the Catalogue of Somatic Mutations in Cancer (COSMIC) for breast, pancreatic, and prostate cancers, for which the COSMIC dataset reports the highest number of chromosomal aberrations. We developed a framework known as GraphChrom for cancer classification. GraphChrom was developed using a graph neural network which models the complex structure of chromosomal aberrations (CA) and provides local connectivity between the aberrations. The proposed framework illustrates three important contributions to the field of cancers. Firstly, it successfully classifies cancer types and subtypes. Secondly, it evolved into a novel data extraction technique which can be used to extract more informative graphs (informative aberrations associated with a sample); and thirdly, it predicts that interCAs (rearrangements between two or more chromosomes) are more effective in cancer prediction than intraCAs (rearrangements within the same chromosome), although intraCAs are three times more likely to occur than intraCAs.
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Mokroš, P. "Chromosomal rearrangements in Arabidopsis mutants revealed by repeated FISH." Plant, Soil and Environment 53, No. 7 (January 7, 2008): 325–28. http://dx.doi.org/10.17221/2206-pse.
Full textAbstract:
The stability of plant nuclear genome is a necessary condition for the faithful transmission of genetic information through cell lineages. When DNA damage occurs due to various impairments, cells start a number of repair processes including ligation of broken chromosomes. As a result, dicentric chromosomes can be formed. Dicentrics are easily detectable as anaphase bridges during following mitosis. Using <i>Arabidopsis</i> as a model plant, we developed a sensitive cytogenetic assay to identify specific chromosomal rearrangements. Here we show <i>Arabidopsis</i> <i>tert<sup>−/−</sup></i> and <i>atm<sup>−/−</sup></i> mutants and their chromosome rearrangements and fusions analysed by fluorescence in situ hybridization (FISH). The method is based on successive rounds of FISH with chromosome-specific probes and the comparison of resulting FISH images.
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Eberl, Daniel F., Arthur J. Hilliker, Cecil B. Sharp, and Silvija N. Trusis-Coulter. "Further observations on the nature of radiation-induced chromosomal interchanges recovered from Drosophila sperm." Genome 32, no. 5 (October 1, 1989): 847–55. http://dx.doi.org/10.1139/g89-521.
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The induction and analysis of numerous translocations (identified genetically and characterized cytologically) between chromosomes 2 and 3 of Drosophila melanogaster have allowed us to reexamine three issues concerning the nature of radiation-induced interchanges in spermatozoa. First, our results support the idea that, relative to their mitotic metaphase length, all major chromosomal regions are similar in their breakability, whether euchromatic (proximal or distal) or heterochromatic. Second, analysis of all our reciprocal exchanges between the two chromosomes shows a statistically significant dependence of the position of the chromosome 2 breakpoint on that of the chromosome 3 breakpoint. Thirdly, our combined cytological and genetic approach strengthens the results of previous analyses, which suggested a strong tendency for chromosomal interchanges to be of the reciprocal type in multiple-break rearrangements. This indicates that if radiation induces chromosome breaks, then the resulting broken ends tend to rejoin in pairs rather than independently.Key words: Drosophila melanogaster, radiation mutagenesis, chromosomal rearrangements, heterochromatin, intercalary heterochromatin.
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Migliazza, A., L. Lombardi, M. Rocchi, D. Trecca, CC Chang, R. Antonacci, NS Fracchiolla, P. Ciana, AT Maiolo, and A. Neri. "Heterogeneous chromosomal aberrations generate 3' truncations of the NFKB2/lyt-10 gene in lymphoid malignancies." Blood 84, no. 11 (December 1, 1994): 3850–60. http://dx.doi.org/10.1182/blood.v84.11.3850.bloodjournal84113850.
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The NFKB2(lyt-10) gene codes for a protein that is a member of the NK- kappa B/rel family of transcription factors containing a DNA-binding rel domain and a carboxy-terminal ankyrin-like domain. The NFKB2 gene represents a candidate proto-oncogene, since it has been found to be involved in a chromosomal translocation t(10;14)(q24;q32) in one case of B-cell lymphoma and in gene rearrangements in various types of lymphoid malignancies. To elucidate the structural and functional consequences of NFKB2 rearrangements, we report the molecular characterization of three novel rearranged NFKB2 genes in lymphoid tumors. In one case of multiple myeloma (MM), cloning and sequencing analysis of reciprocal breakpoint sites showed that they occurred within intron 15 of the NFKB2 gene and led to the complete deletion of the 32 portion of the gene coding for the ankyrin domain. Fluorescent in situ hybridization (FISH) analysis showed that the novel regions involved in the NFKB2 rearrangement originated from chromosome 7q34, thus implying the occurrence of a t(7;10)(q34;q24) reciprocal chromosomal translocation. In one case of T-cell cutaneous lymphoma (CTCL) and in one of B-cell chronic lymphocytic leukemia (B-CLL), NFKB2 rearrangements occurred, respectively, within exons 18 and 20 of the gene and involved recombinations with distinct regions of chromosome 10q24. Molecular analysis suggested that these rearrangements may occur as a consequence of small internal chromosomal deletions. In both of these cases, the rearrangements led to specific carboxy-terminal truncations of NFKB2 generating abnormal transcripts that coded for proteins lacking portions of the ankyrin domain. These proteins localize in the nucleus, suggesting their constitutive activation in vivo. Overall, our results indicate that NFKB2 rearrangements in lymphoid neoplasia may occur by heterogeneous mechanisms, including internal chromosomal deletion or chromosomal translocation. The common consequence of these rearrangements appears to be the deletion of 32 sequences of NFKB2 leading to the production of carboxy-truncated constitutively nuclear proteins that may be involved in tumorigenesis.
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Dahiya, Rashmi, and Peter Ly. "Abstract A014: Modeling recurrent chromosomal alterations in renal cell carcinoma evolution." Cancer Research 83, no. 16_Supplement (August 15, 2023): A014. http://dx.doi.org/10.1158/1538-7445.kidney23-a014.
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Abstract The loss of one copy of chromosome 3p represents an early truncal genetic event in the majority of clear cell renal cell carcinoma (ccRCC) tumors. Chromosome 3p loss can be initiated by chromothripsis, a process in which mis-segregated chromosomes entrapped within abnormal nuclear structures called micronuclei become pulverized into small genomic fragments. These fragments are then re-stitched together to form complex rearrangements that are accompanied by extensive segmental deletions that inactivate critical tumor suppressor genes located on chromosome 3p. Despite being a driver of ccRCC development, the mechanism(s) that initiate chromosome 3p chromothripsis followed by pressures that select for specific rearrangement patterns are poorly understood. To recapitulate early genetic events arising throughout ccRCC evolution, here we developed chromosome 3p-specific micronuclei models in non-transformed human renal proximal tubule epithelial cells (RPTECs) to interrogate recurrent patterns of chromosomal alterations that promote renal cell tumorigenesis. To do so, we used CRISPR/Cas9 to induce a DNA double-strand break on chromosome 3p, which generates chromosome 3p-specific micronuclei when the acentric arm is left unrepaired into the subsequent mitosis. DNA fluorescence in situ hybridization revealed that mis-segregation of chromosome 3p into micronuclei induces chromosome pulverization and rearrangements. Notably, these alterations are sufficient to provide a selective advantage by enabling anchorage-independent growth in vitro. Cytogenetic characterization of partially transformed RPTECs revealed enrichment of chromosome 3p rearrangements, which were gradually lost upon propagation as conventional monolayer cultures. These results provide mechanistic insight into the origins of chromosome 3p alterations in ccRCC and further highlight the role of selection pressure in shaping genome evolution. Citation Format: Rashmi Dahiya, Peter Ly. Modeling recurrent chromosomal alterations in renal cell carcinoma evolution [abstract]. In: Proceedings of the AACR Special Conference: Advances in Kidney Cancer Research; 2023 Jun 24-27; Austin, Texas. Philadelphia (PA): AACR; Cancer Res 2023;83(16 Suppl):Abstract nr A014.
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Ruiz, José F., Belén Gómez-González, and Andrés Aguilera. "Chromosomal Translocations Caused by Either Pol32-Dependent or Pol32-Independent Triparental Break-Induced Replication." Molecular and Cellular Biology 29, no. 20 (August 3, 2009): 5441–54. http://dx.doi.org/10.1128/mcb.00256-09.
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ABSTRACT Double-strand breaks (DSBs) are harmful DNA lesions that can generate chromosomal rearrangements or chromosome losses if not properly repaired. Despite their association with a number of genetic diseases and cancer, the mechanisms by which DSBs cause rearrangements remain unknown. Using a newly developed experimental assay for the analysis of translocations occurring between two chromosomes in S accharomyces cerevisiae, we found that a single DSB located on one chromosome uses a short homologous sequence found in a third chromosome as a bridge to complete DSB repair, leading to chromosomal translocations. Such translocations are dramatically reduced when the short homologous sequence on the third chromosome is deleted. Translocations rely on homologous recombination (HR) proteins, such as Rad51, Rad52, and Rad59, as well as on the break-induced replication-specific protein Pol32 and on Srs2, but not on Ku70. Our results indicate that a single chromosomal DSB efficiently searches for short homologous sequences throughout the genome for its repair, leading to triparental translocations between heterologous chromosomes. Given the abundance of repetitive DNA in eukaryotic genomes, the results of this study open the possibility that HR rather than nonhomologous end joining may be a major source of chromosomal translocations.
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Nascimento, Carolina Gama, Joana Rosa Marques Prota, Ilária Cristina Sgardioli, Samira Spineli-Silva, Nilma Lúcia Viguetti Campos, Vera Lúcia Gil-da-Silva-Lopes, and Társis Paiva Vieira. "Rare 15q21.1q22.31 Duplication Due to a Familial Chromosomal Insertion and Diagnostic Investigation in a Carrier of Balanced Chromosomal Rearrangement and Intellectual Disability." Genes 14, no. 4 (April 9, 2023): 885. http://dx.doi.org/10.3390/genes14040885.
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Insertions are rare balanced chromosomal rearrangements with an increased risk of imbalances for the offspring. Moreover, balanced rearrangements in individuals with abnormal phenotypes may be associated to the phenotype by different mechanisms. This study describes a three-generation family with a rare chromosomal insertion. G-banded karyotype, chromosomal microarray analysis (CMA), whole-exome sequencing (WES), and low-pass whole-genome sequencing (WGS) were performed. Six individuals had the balanced insertion [ins(9;15)(q33;q21.1q22.31)] and three individuals had the derivative chromosome 9 [der(9)ins(9;15)(q33;q21.1q22.31)]. The three subjects with unbalanced rearrangement showed similar clinical features, including intellectual disability, short stature, and facial dysmorphisms. CMA of these individuals revealed a duplication of 19.3 Mb at 15q21.1q22.31. A subject with balanced rearrangement presented with microcephaly, severe intellectual disability, absent speech, motor stereotypy, and ataxia. CMA of this patient did not reveal pathogenic copy number variations and low-pass WGS showed a disruption of the RABGAP1 gene at the 9q33 breakpoint. This gene has been recently associated with a recessive disorder, which is not compatible with the mode of inheritance in this patient. WES revealed an 88 bp deletion in the MECP2 gene, consistent with Rett syndrome. This study describes the clinical features associated with the rare 15q21.1–q22.31 duplication and reinforces that searching for other genetic causes is warranted for individuals with inherited balanced chromosomal rearrangements and abnormal phenotypes.
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Mendez-Rosado, Luis, Araceli Lantigua, Juan Galarza, Ahmed Hamid Al-Rikabi, Monika Ziegler, and Thomas Liehr. "Unusual de novo Partial Trisomy 17p12p11.2 due to Unbalanced Insertion into 5p13.1 in a Severely Affected Boy." Journal of Pediatric Genetics 06, no. 03 (March 7, 2017): 165–68. http://dx.doi.org/10.1055/s-0037-1599195.
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AbstractGain of copy numbers can be due to different chromosomal rearrangements such as direct or indirect duplications, translocations, small supernumerary marker chromosomes, or insertions. In a 3-year-old boy with dysmorphic features and developmental delay, chromosome analyses revealed a derivative chromosome 5. Microdissection and reverse fluorescence in situ hybridization identified the in 5p13.1 inserted part as 17p12-p11.2 material. Thus the patient suffered from a rare combination of genomic disorder, that is, Charcot-Marie-Tooth disease type 1A and Potocki-Lupski syndrome. Parental studies indicated that the abnormality was de novo in origin. As the question how this rearrangement arose cannot be answered conclusively, formal genetic counseling is warranted, which includes a discussion regarding the possibility of gonadal mosaicism. In conclusion, this case highlights that chromosome 17p is genetically relatively instable, and thus it can lead to rare chromosomal conditions.
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Putnam, Christopher D., Vincent Pennaneach, and Richard D. Kolodner. "Saccharomyces cerevisiae as a Model System To Define the Chromosomal Instability Phenotype." Molecular and Cellular Biology 25, no. 16 (August 15, 2005): 7226–38. http://dx.doi.org/10.1128/mcb.25.16.7226-7238.2005.
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ABSTRACT Translocations, deletions, and chromosome fusions are frequent events seen in cancers with genome instability. Here we analyzed 358 genome rearrangements generated in Saccharomyces cerevisiae selected by the loss of the nonessential terminal segment of chromosome V. The rearrangements appeared to be generated by both nonhomologous end joining and homologous recombination and targeted all chromosomes. Fifteen percent of the rearrangements occurred independently more than once. High levels of specific classes of rearrangements were isolated from strains with specific mutations: translocations to Ty elements were increased in telomerase-defective mutants, potential dicentric translocations and dicentric isochromosomes were associated with cell cycle checkpoint defects, chromosome fusions were frequent in strains with both telomerase and cell cycle checkpoint defects, and translocations to homolog genes were seen in strains with defects allowing homoeologous recombination. An analysis of human cancer-associated rearrangements revealed parallels to the effects that strain genotypes have on classes of rearrangement in S. cerevisiae.
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Arya, Priyanka, Jennelle C. Hodge, Peggy A. Matlock, Gail H. Vance, and Amy M. Breman. "Two Patients with Complex Rearrangements Suggestive of Germline Chromoanagenesis." Cytogenetic and Genome Research 160, no. 11-12 (2020): 671–79. http://dx.doi.org/10.1159/000512898.
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Chromoanagenesis, a phenomenon characterized by complex chromosomal rearrangement and reorganization events localized to a limited number of genomic regions, includes the subcategories chromothripsis, chromoanasynthesis, and chromoplexy. Although definitions of these terms are evolving, constitutional chromoanagenesis events have been reported in a limited number of patients with variable phenotypes. We report on 2 cases with complex genomic events characterized by multiple copy number gains and losses confined to a single chromosome region, which are suggestive of constitutional chromoanagenesis. Case 1 is a 43-year-old male with intellectual disability and recently developed generalized tonic-clonic seizures. Chromosomal microarray analysis identified a complex rearrangement involving chromosome region 14q31.1q32.2, consisting of 16 breakpoints ranging in size from 0.2 to 6.2 Mb, with 5 segments of normal copy number present between these alterations. Interestingly, this case represents the oldest known patient with a complex rearrangement indicative of constitutional chromoanagenesis. Case 2 is a 2-year-old female with developmental delay, speech delay, low muscle tone, and seizures. Chromosomal microarray analysis identified a complex rearrangement consisting of 28 breakpoints localized to 18q21.32q23. The size of the copy number alterations ranged from 0.042 to 5.1 Mb, flanked by 12 small segments of normal copy number. These cases add to a growing body of literature demonstrating complex chromosomal rearrangements as a disease mechanism for congenital anomalies.
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Kovaleva, Natalia V., and Philip D. Cotter. "Factors affecting clinical manifestation of chromosomal imbalance in carriers of segmental autosomal mosaicism: differential impact of gender." Journal of Applied Genetics 63, no. 2 (January 1, 2022): 281–91. http://dx.doi.org/10.1007/s13353-021-00673-w.
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Abstract Mosaicism for unbalanced chromosomal rearrangements segmental mosaicism (SM) is rare, both in patients referred for cytogenetic testing and in prenatal diagnoses. In contrast, in preimplantation embryos SM is a frequent finding and, therefore, is even more challenging. However, there is no consistency among results of published studies on the clinical outcomes of embryos with SM, primarily due to the small number of reported cases. Moreover, there is the problem of predicting the potential for the optimal development of a mosaic embryo to a healthy individual. Therefore, we suggested comparing factors predisposing to favorable and poor prognoses, identified in postnatal and prenatal cohorts of SM carriers, with those obtained from studies on preimplantation embryos. We analyzed 580 published cases of SM including (i) postnatally diagnosed affected carriers, (ii) clinically asymptomatic carriers, (iii) prenatally diagnosed carriers, and (iv) miscarriages. We observed a concordance with preimplantation diagnoses regarding the clinical significance of the extent of mosaicism as well as a predominance of deletions over other types of rearrangements. However, there is no concordance regarding excessive involvement of chromosomes 1, 5, and 9 in unbalanced rearrangements and a preferential involvement of larger chromosomes compared to short ones. Paternal age was not found to be associated with SM in postnatally disease-defined individuals. We have identified maternal age and preferential involvement of chromosome 18 in rearrangements associated with clinical manifestations. Male predominance was found among normal pregnancy outcomes and among disease-defined carriers of rearrangements resulting in a gain of genomic material. Female predominance was found among abnormal pregnancy outcomes, among disease-defined carriers of loss and gain/loss rearrangements, and among transmitting carriers of gonadal SM, both affected and asymptomatic. According to data obtained from “post-embryo” studies, clinical manifestations of chromosomal imbalance are associated with a high proportion of abnormal cells, female gender, the type of rearrangement and involved chromosome(s), and maternal age. We believe these data are instructive in the challenging medical genetic counseling of parents faced with no option other than transfer of an embryo with segmental mosaicism.
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Лязина, Л. В., А. С. Уварова, М. В. Смирнова, А. А. Пендина, and О. В. Малышева. "Inherited type of chromosomal microstructural rearrangements." Nauchno-prakticheskii zhurnal «Medicinskaia genetika», no. 3() (March 30, 2020): 32–34. http://dx.doi.org/10.25557/2073-7998.2020.03.32-34.
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Представлены семейные случаи микроструктурных перестроек с вариабельной клинической картиной: синдром микродупликации Xq28 (MECP2) с классическим фенотипом у девочки вследствие несбалансированной транслокации Х-хромосомы и хромосомы 4, унаследованной от матери, имеющей сбалансированный кариотип, и синдром делеции 22q11 (Ди Джорджи) с разной клинической картиной у сестер, у отца которых наблюдался редкий вариант сбалансированной структурной перестройки с маркерной хромосомой. We present cases of chromosomal microstructural rearrangements in families with variable phenotypes: microduplication syndrome Xq28 (MECP2) in a girl with typical dismorphic features as a result of an unbalanced translocation between X-chromosome and chromosome 4 inherited from the mother who had a balanced aberration, and DiGeorgy syndrome with variable features in sisters that was inherited from the father carrying a rare balanced structural rearrangement with a marker chromosome.
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Briscoe, Albert, and John E. Tomkiel. "Chromosomal Position Effects Reveal Different cis-Acting Requirements for rDNA Transcription and Sex Chromosome Pairing in Drosophila melanogaster." Genetics 155, no. 3 (July 1, 2000): 1195–211. http://dx.doi.org/10.1093/genetics/155.3.1195.
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Abstract In Drosophila melanogaster, the rDNA loci function in ribosome biogenesis and nucleolar formation and also as sex chromosome pairing sites in male meiosis. These activities are not dependent on the heterochromatic location of the rDNA, because euchromatic transgenes are competent to form nucleoli and restore pairing to rDNA-deficient X chromosomes. These transgene studies, however, do not address requirements for the function of the endogenous rDNA loci within the heterochromatin. Here we describe two chromosome rearrangements that disrupt rDNA functions. Both rearrangements are translocations that cause an extreme bobbed visible phenotype and XY nondisjunction and meiotic drive in males. However, neither rearrangement interacts with a specific Y chromosome, Ymal+, that induces male sterility in combination with rDNA deletions. Molecular studies show that the translocations are not associated with gross rearrangements of the rDNA repeat arrays. Rather, suppression of the bobbed phenotypes by Y heterochromatin suggests that decreased rDNA function is caused by a chromosomal position effect. While both translocations affect rDNA transcription, only one disrupts meiotic XY pairing, indicating that there are different cis-acting requirements for rDNA transcription and rDNA-mediated meiotic pairing.
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Bastard, C., C. Deweindt, JP Kerckaert, B. Lenormand, A. Rossi, F. Pezzella, C. Fruchart, C. Duval, M. Monconduit, and H. Tilly. "LAZ3 rearrangements in non-Hodgkin's lymphoma: correlation with histology, immunophenotype, karyotype, and clinical outcome in 217 patients." Blood 83, no. 9 (May 1, 1994): 2423–27. http://dx.doi.org/10.1182/blood.v83.9.2423.2423.
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Abstract We have recently shown that an evolutionary conserved gene LAZ3, encoding a zinc finger protein, is disrupted and overexpressed in some B-cell lymphomas (mainly with a large cell component) that show chromosomal rearrangements involving 3q27. Because the breakpoints involved in these rearrangements are focused in a narrow major translocation cluster (MTC) on chromosome 3, we used genomic probes from this region to study the molecular rearrangements of LAZ3 in a large series of patients (217) with non-Hodgkin's lymphoma (NHL). Southern blot analysis showed LAZ3 rearrangement in 43 patients (19.8%). Rearrangement was found in 11 of the 84 patients (13%) with follicular lymphoma but was most frequent in aggressive lymphoma (diffuse mixed, diffuse large cell, and large cell immunoblastic subtypes), in which 31 of the 114 patients (27%) were affected. The highest proportion of LAZ3 alteration was observed in B-cell aggressive lymphoma (26 of 71 cases, 37%). Eleven of the 32 patients with 3q27 chromosomal abnormality had no LAZ3 rearrangement, suggesting the possibility of LAZ3 involvement outside the MTC. On the other hand, 18 of the 39 patients with LAZ3 rearrangement and available cytogenetic results did not have visible chromosomal break at 3q27, suggesting that almost a half of the rearrangements are not detectable by cytogenetic methods. No statistical association could be found between LAZ3 status and initial features of the disease or clinical outcome in either follicular or aggressive lymphomas. We conclude that LAZ3 alteration is a relatively frequent event in B-cell lymphoma, especially in those of aggressive histology. It could be used as a genomic marker of the disease, and further studies are needed to clarify clinical implications of these alterations.
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Bastard, C., C. Deweindt, JP Kerckaert, B. Lenormand, A. Rossi, F. Pezzella, C. Fruchart, C. Duval, M. Monconduit, and H. Tilly. "LAZ3 rearrangements in non-Hodgkin's lymphoma: correlation with histology, immunophenotype, karyotype, and clinical outcome in 217 patients." Blood 83, no. 9 (May 1, 1994): 2423–27. http://dx.doi.org/10.1182/blood.v83.9.2423.bloodjournal8392423.
Full textAbstract:
We have recently shown that an evolutionary conserved gene LAZ3, encoding a zinc finger protein, is disrupted and overexpressed in some B-cell lymphomas (mainly with a large cell component) that show chromosomal rearrangements involving 3q27. Because the breakpoints involved in these rearrangements are focused in a narrow major translocation cluster (MTC) on chromosome 3, we used genomic probes from this region to study the molecular rearrangements of LAZ3 in a large series of patients (217) with non-Hodgkin's lymphoma (NHL). Southern blot analysis showed LAZ3 rearrangement in 43 patients (19.8%). Rearrangement was found in 11 of the 84 patients (13%) with follicular lymphoma but was most frequent in aggressive lymphoma (diffuse mixed, diffuse large cell, and large cell immunoblastic subtypes), in which 31 of the 114 patients (27%) were affected. The highest proportion of LAZ3 alteration was observed in B-cell aggressive lymphoma (26 of 71 cases, 37%). Eleven of the 32 patients with 3q27 chromosomal abnormality had no LAZ3 rearrangement, suggesting the possibility of LAZ3 involvement outside the MTC. On the other hand, 18 of the 39 patients with LAZ3 rearrangement and available cytogenetic results did not have visible chromosomal break at 3q27, suggesting that almost a half of the rearrangements are not detectable by cytogenetic methods. No statistical association could be found between LAZ3 status and initial features of the disease or clinical outcome in either follicular or aggressive lymphomas. We conclude that LAZ3 alteration is a relatively frequent event in B-cell lymphoma, especially in those of aggressive histology. It could be used as a genomic marker of the disease, and further studies are needed to clarify clinical implications of these alterations.
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Queiroz, Marisa V. de, Aline Aparecida Pizzirani-Kleiner, and João Lúcio Azevedo. "Electrophoretic characterization of Aspergillus nidulans strains with chromosomal duplications." Genetics and Molecular Biology 23, no. 2 (June 2000): 293–97. http://dx.doi.org/10.1590/s1415-47572000000200009.
Full textAbstract:
Pulsed-field gel electrophoresis was used to characterize strains of Aspergillus nidulans with a chromosomal duplication Dp(I-II). Morphologically deteriorated and improved variants of these strains were also analyzed. The electrophoretic karyotype demonstrated that in two duplicated strains (A and B) the 4.2 Mb band, which corresponds to chromosome II, was absent and a new band was observed. Hybridization studies using the uapA (chromosome I) and wA (chromosome II) genes demonstrated that the new band corresponded to chromosome II plus the duplicated segment of chromosome I. The size of the chromosomal duplication was approximately 1.0 Mb. Analysis of the chromosomal bands of a morphologically improved strain showed that the duplicated segment of chromosome I was completely lost. The morphologically deteriorated variants V9 and V17 had the same karyotype as the duplicated strains. However, the deteriorated variant V5 lost part of chromosome I and had a rearrangement involving chromosome V. This rearrangement may have resulted from the mutagenic treatment used to obtain the genetic markers. Pulsed-field gel electrophoresis was found to be an excellent tool for locating chromosomal rearrangements.
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Lo, Anthony W. I., Carl N. Sprung, Bijan Fouladi, Mehrdad Pedram, Laure Sabatier, Michelle Ricoul, Gloria E. Reynolds, and John P. Murnane. "Chromosome Instability as a Result of Double-Strand Breaks near Telomeres in Mouse Embryonic Stem Cells." Molecular and Cellular Biology 22, no. 13 (July 1, 2002): 4836–50. http://dx.doi.org/10.1128/mcb.22.13.4836-4850.2002.
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ABSTRACT Telomeres are essential for protecting the ends of chromosomes and preventing chromosome fusion. Telomere loss has been proposed to play an important role in the chromosomal rearrangements associated with tumorigenesis. To determine the relationship between telomere loss and chromosome instability in mammalian cells, we investigated the events resulting from the introduction of a double-strand break near a telomere with I-SceI endonuclease in mouse embryonic stem cells. The inactivation of a selectable marker gene adjacent to a telomere as a result of the I-SceI-induced double-strand break involved either the addition of a telomere at the site of the break or the formation of inverted repeats and large tandem duplications on the end of the chromosome. Nucleotide sequence analysis demonstrated large deletions and little or no complementarity at the recombination sites involved in the formation of the inverted repeats. The formation of inverted repeats was followed by a period of chromosome instability, characterized by amplification of the subtelomeric region, translocation of chromosomal fragments onto the end of the chromosome, and the formation of dicentric chromosomes. Despite this heterogeneity, the rearranged chromosomes eventually acquired telomeres and were stable in most of the cells in the population at the time of analysis. Our observations are consistent with a model in which broken chromosomes that do not regain a telomere undergo sister chromatid fusion involving nonhomologous end joining. Sister chromatid fusion is followed by chromosome instability resulting from breakage-fusion-bridge cycles involving the sister chromatids and rearrangements with other chromosomes. This process results in highly rearranged chromosomes that eventually become stable through the addition of a telomere onto the broken end. We have observed similar events after spontaneous telomere loss in a human tumor cell line, suggesting that chromosome instability resulting from telomere loss plays a role in chromosomal rearrangements associated with tumor cell progression.
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Eldridge, M. D. B., P. G. Johnston, R. L. Close, and P. S. Lowry. "Chromosomal rearrangements in rock wallabies, Petrogale (Marsupialia: Macropodidae). II. G-banding analysis of Petrogale godmani." Genome 32, no. 6 (December 1, 1989): 935–40. http://dx.doi.org/10.1139/g89-534.
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Chromosomal rearrangements in the two currently recognised races of Petrogale godmani were examined using C- and G-banding. The nominate race P. godmani godmani (2n = 20) was found to possess an inverted chromosome 5 and an acrocentric 6–10 fusion, which can be derived from a 6–10 centric fusion by a centromeric transposition. The Cape York race (2n = 22) was found to retain the ancestral submetacentric chromosome 4 and the ancestral chromosome 5. Thus despite their genie similarity, the two races clearly have major chromosomal differences and should be regarded as separate species. Petrogale g. godmani shares two derived chromosomes with another Queensland taxon, the assimilis race of P. assimilis, indicating recent common ancestry. The Cape York race retains characteristics of an ancestral stock of Petrogale and its genic similarity with P. g. godmani could therefore be the result of extensive introgression.Key words: chromosomal rearrangements, G-banding, Marsupialia, Petrogale.
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Quenu, Mathieu, Artemis D. Treindl, Kate Lee, Daigo Takemoto, Torsten Thünen, Samad Ashrafi, David Winter, et al. "Telomere-to-Telomere Genome Sequences across a Single Genus Reveal Highly Variable Chromosome Rearrangement Rates but Absolute Stasis of Chromosome Number." Journal of Fungi 8, no. 7 (June 25, 2022): 670. http://dx.doi.org/10.3390/jof8070670.
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Genome rearrangements in filamentous fungi are prevalent but little is known about the modalities of their evolution, in part because few complete genomes are available within a single genus. To address this, we have generated and compared 15 complete telomere-to-telomere genomes across the phylogeny of a single genus of filamentous fungi, Epichloë. We find that the striking distinction between gene-rich and repeat-rich regions previously reported for isolated species is ubiquitous across the Epichloë genus. We built a species phylogeny from single-copy gene orthologs to provide a comparative framing to study chromosome composition and structural change through evolutionary time. All Epichloë genomes have exactly seven nuclear chromosomes, but despite this conserved ploidy, analyses reveal low synteny and substantial rearrangement of gene content across the genus. These rearrangements are highly lineage-dependent, with most occurring over short evolutionary distances, with long periods of structural stasis. Quantification of chromosomal rearrangements shows they are uncorrelated with numbers of substitutions and evolutionary distances, suggesting that different modes of evolution are acting to create nucleotide and chromosome-scale changes.
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Kim, Jaebum, Marta Farré, Loretta Auvil, Boris Capitanu, Denis M. Larkin, Jian Ma, and Harris A. Lewin. "Reconstruction and evolutionary history of eutherian chromosomes." Proceedings of the National Academy of Sciences 114, no. 27 (June 19, 2017): E5379—E5388. http://dx.doi.org/10.1073/pnas.1702012114.
Full textAbstract:
Whole-genome assemblies of 19 placental mammals and two outgroup species were used to reconstruct the order and orientation of syntenic fragments in chromosomes of the eutherian ancestor and six other descendant ancestors leading to human. For ancestral chromosome reconstructions, we developed an algorithm (DESCHRAMBLER) that probabilistically determines the adjacencies of syntenic fragments using chromosome-scale and fragmented genome assemblies. The reconstructed chromosomes of the eutherian, boreoeutherian, and euarchontoglires ancestor each included >80% of the entire length of the human genome, whereas reconstructed chromosomes of the most recent common ancestor of simians, catarrhini, great apes, and humans and chimpanzees included >90% of human genome sequence. These high-coverage reconstructions permitted reliable identification of chromosomal rearrangements over ∼105 My of eutherian evolution. Orangutan was found to have eight chromosomes that were completely conserved in homologous sequence order and orientation with the eutherian ancestor, the largest number for any species. Ruminant artiodactyls had the highest frequency of intrachromosomal rearrangements, and interchromosomal rearrangements dominated in murid rodents. A total of 162 chromosomal breakpoints in evolution of the eutherian ancestral genome to the human genome were identified; however, the rate of rearrangements was significantly lower (0.80/My) during the first ∼60 My of eutherian evolution, then increased to greater than 2.0/My along the five primate lineages studied. Our results significantly expand knowledge of eutherian genome evolution and will facilitate greater understanding of the role of chromosome rearrangements in adaptation, speciation, and the etiology of inherited and spontaneously occurring diseases.
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Bayani, Jane, Maria Zielenska, Paula Marrano, Yim Kwan Ng, Michael D. Taylor, Venita Jay, James T. Rutka, and Jeremy A. Squire. "Molecular cytogenetic analysis of medulloblastomas and supratentorial primitive neuroectodermal tumors by using conventional banding, comparative genomic hybridization, and spectral karyotyping." Journal of Neurosurgery 93, no. 3 (September 2000): 437–48. http://dx.doi.org/10.3171/jns.2000.93.3.0437.
Full textAbstract:
Object. Medulloblastomas and related primitive neuroectodermal tumors (PNETs) of the central nervous system are malignant, invasive embryonal tumors with predominantly neuronal differentiation that comprise 20% of pediatric brain tumors. Cytogenetic analysis has shown that alterations in chromosome 17, particularly the loss of 17p and the formation of isochromosome 17q, as well as the gain of chromosome 7 are the most common changes among this group of tumors. Comparative genomic hybridization (CGH) studies have largely confirmed these cytogenetic findings and have also identified novel regions of gain, loss, and amplification. The advent of more sophisticated multicolored fluorescence in situ hybridization (FISH) procedures such as spectral karyotyping (SKY) now permits complete recognition of all aberrations including extremely complex rearrangements. The authors report a retrospective analysis of 19 medulloblastoma and five PNET cases studied using combinations of classic banding analysis, FISH, CGH, and SKY to examine comprehensively the chromosomal aberrations present in this tumor group and to attempt to identify common structural rearrangement(s).Methods. The CGH data demonstrate gains of chromosomes 17q and 7 in 60% of the tumors studied, which confirms data reported in the current literature. However, the authors have also combined the results of all three molecular cytogenetic assays (Giemsa banding, CGH, and SKY) to reveal the frequency of chromosomal rearrangement (gained, lost, or involved in structural rearrangement).Conclusions. The combined results indicate that chromosomes 7 and 17 are the most frequently rearranged chromosomes (10.1% and 8.9%, respectively, in all rearrangements detected). Furthermore, chromosomes 3 (7.8%), 14 (7%), 10 (6.7%), and 22 (6.5%) were also found to be frequently rearranged, followed by chromosomes 6 (6.5%), 13 (6.2%), and 18 (6.2%). Eight (33%) of 24 tumors exhibited high-level gains or gene amplification. Amplification of MYCN was identified in four tumors, whereas amplification of MYCC was identified in one tumor. One tumor exhibited a high-level gain of chromosome 9p. Additionally, desmoplastic medulloblastomas and large-cell medulloblastomas exhibited higher karyotype heterogeneity, amplification, and aneusomy than classic medulloblastomas.
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Baik, Jong Youn, Hye Jin Han, and Kelvin H. Lee. "DNA Double-Strand Breaks Affect Chromosomal Rearrangements during Methotrexate-Mediated Gene Amplification in Chinese Hamster Ovary Cells." Pharmaceutics 13, no. 3 (March 12, 2021): 376. http://dx.doi.org/10.3390/pharmaceutics13030376.
Full textAbstract:
Methotrexate (MTX)-mediated gene amplification has been widely used in Chinese hamster ovary (CHO) cells for the biomanufacturing of therapeutic proteins. Although many studies have reported chromosomal instability and extensive chromosomal rearrangements in MTX-mediated gene-amplified cells, which may be associated with cell line instability issues, the mechanisms of chromosomal rearrangement formation remain poorly understood. We tested the impact of DNA double-strand breaks (DSBs) on chromosomal rearrangements using bleomycin, a DSB-inducing reagent. Bleomycin-treated CHO-DUK cells, which are one of the host cell lines deficient in dihydrofolate reductase (Dhfr) activity, exhibited a substantial number of cells containing radial formations or non-radial formations with chromosomal rearrangements, suggesting that DSBs may be associated with chromosomal rearrangements. To confirm the causes of DSBs during gene amplification, we tested the effects of MTX treatment and the removal of nucleotide base precursors on DSB formation in Dhfr-deficient (i.e., CHO-DUK) and Dhfr-expressing (i.e., CHO-K1) cells. Immunocytochemistry demonstrated that MTX treatment did not induce DSBs per se, but a nucleotide shortage caused by the MTX-mediated inhibition of Dhfr activity resulted in DSBs. Our data suggest that a nucleotide shortage caused by MTX-mediated Dhfr inhibition in production cell lines is the primary cause of a marked increase in DSBs, resulting in extensive chromosomal rearrangements after gene amplification processes.
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Vanjari, Neelam, Guilin Tang, Gokce A. Toruner, Wei Wang, Beenu Thakral, Ming Zhao, Bhavana J. Dave, Joseph D. Khoury, L. Jeffrey Medeiros, and Zhenya Tang. "Optical Genome Mapping Helps to Identify BCR::JAK2 Rearrangement Arising from Cryptic Complex Chromosomal Aberrations: A Case Report and Literature Review." Genes 14, no. 12 (December 8, 2023): 2188. http://dx.doi.org/10.3390/genes14122188.
Full textAbstract:
We report a case of myeloproliferative neoplasm, not otherwise specified (MPN-NOS)-transformed AML with BCR::JAK2 rearrangement. Chromosomal analysis indicated a simple abnormal karyotype 46,XY,t(7;17)(q21;q24),t(9;22)(p24;q11.2). Fluorescence in situ hybridization (FISH) using a BCR/ABL1/ASS1 probe set suggested a possible BCR rearrangement and a reflex JAK2 breakapart probe indicated JAK2 rearrangement, most likely partnered with BCR. Optical genome mapping (OGM) analysis confirmed BCR::JAK2 derived through an inv(9)(p24p13) after a t(9;22)(p13;q11.2) in this case. Due to the complexity of chromosomal aberrations, disruption and/or rearrangement of other genes such as KIF24::BCR, JAK2::KIF24/UBAP1, and CDK6:SOX9 were also identified by OGM. Although the functionality and clinical importance of these novel rearrangements were unknown, disruption of these genes might be associated with a poorer response to chemotherapy and disease progression. We also reviewed all cases with BCR::JAK2 rearrangement reported in the literature. In conclusion, a suspected t(9;22)/BCR::JAK2 rearrangement warrants further characterization with genomic assays such as OGM, whole chromosome sequencing, and RNA sequencing to explore other gene disruptions and/or rearrangements.
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Son, Han Joon, and Jong Ho Lee. "Novel Four-Way Variant Translocation, t(1;9;22;16)(q21;q34;q11.2;q24), in a Patient with Chronic Myeloid Leukemia." Diagnostics 14, no. 3 (January 30, 2024): 303. http://dx.doi.org/10.3390/diagnostics14030303.
Full textAbstract:
Chronic myeloid leukemia (CML) is characterized by the Philadelphia (Ph) chromosome resulting from the translocation of t(9;22)(q34;q11), producing the BCR::ABL1 fusion gene. Variant Ph chromosome translocations, involving rearrangements in chromosomes other than 9 and 22, occur in 5–10% of CML cases. Herein, we report a unique case of a 36-year-old male with a four-way variant Ph chromosome. Conventional chromosomal analysis performed on bone marrow aspirate samples showed 46, XY, t(1;9;22;16)(q21;q34;q11.2;q24). Nested RT-PCR of the BCR::ABL1 gene revealed a major BCR::ABL rearrangement. The treatment with nilotinib achieved a complete hematologic, cytogenetic, and molecular response after 12 months.
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Mottola, Filomena, Marianna Santonastaso, Valentina Ronga, Renata Finelli, and Lucia Rocco. "Polymorphic Rearrangements of Human Chromosome 9 and Male Infertility: New Evidence and Impact on Spermatogenesis." Biomolecules 13, no. 5 (April 23, 2023): 729. http://dx.doi.org/10.3390/biom13050729.
Full textAbstract:
Chromosomal polymorphisms are structural variations in chromosomes that define the genomic variance of a species. These alterations are recurrent in the general population, and some of them appear to be more recurrent in the infertile population. Human chromosome 9 is highly heteromorphic, and how its rearrangement affects male fertility remains to be fully investigated. In this study, we aimed to investigate the association between the polymorphic rearrangements of chromosome 9 and male infertility via an Italian cohort of male infertile patients. Cytogenetic analysis was carried out, along with Y microdeletion screening, semen analysis, fluorescence in situ hybridization, and TUNEL assays using spermatic cells. Chromosome 9 rearrangements were observed in six patients: three of them showed a pericentric inversion, while the others showed a polymorphic heterochromatin variant 9qh. Of these, four patients exhibited oligozoospermia associated with teratozoospermia, along with a percentage of aneuploidy in the sperm of above 9%, in particular, an increase in XY disomy. Additionally, high values for sperm DNA fragmentation (≥30%) were observed in two patients. None of them had microdeletions to the AZF loci on chromosome Y. Our results suggest that polymorphic rearrangements of chromosome 9 might be associated with abnormalities in sperm quality due to incorrect spermatogenesis regulation.
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Pinheiro, Melquizedec Luiz Silva, Cleusa Yoshiko Nagamachi, Talita Fernanda Augusto Ribas, Cristovam Guerreiro Diniz, Patricia Caroline Mary O´Brien, Malcolm Andrew Ferguson-Smith, Fengtang Yang, and Julio Cesar Pieczarka. "Chromosomal painting in Charadrius collaris Vieillot, 1818 and Vanellus chilensis Molina, 1782 and an analysis of chromosomal signatures in Charadriiformes." PLOS ONE 17, no. 8 (August 10, 2022): e0272836. http://dx.doi.org/10.1371/journal.pone.0272836.
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Charadriiformes represent one of the largest orders of birds; members of this order are diverse in morphology, behavior and reproduction, making them an excellent model for studying evolution. It is accepted that the avian putative ancestral karyotype, with 2n = 80, remains conserved for about 100 million years. So far, only a few species of Charadriiformes have been studied using molecular cytogenetics. Here, we performed chromosome painting on metphase chromosomes of two species of Charadriidae, Charadrius collaris and Vanellus chilensis, with whole chromosome paint probes from Burhinus oedicnemus. Charadrius collaris has a diploid number of 76, with both sex chromosomes being submetacentric. In V. chilensi a diploid number of 78 was identified, and the Z chromosome is submetacentric. Chromosome painting suggests that chromosome conservation is a characteristic common to the family Charadriidae. The results allowed a comparative analysis between the three suborders of Charadriiformes and the order Gruiformes using chromosome rearrangements to understand phylogenetic relationships between species and karyotypic evolution. However, the comparative analysis between the Charadriiformes suborders so far has not revealed any shared rearrangements, indicating that each suborder follows an independent evolutionary path, as previously proposed. Likewise, although the orders Charadriiformes and Gruiformes are placed on sister branches, they do not share any signature chromosomal rearrangements.
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Campos, Ana Eduarda, Carla Rosenberg, Ana Krepischi, Marina França, Vanessa Lopes, Viviane Nakano, Tânia Vertemati, et al. "An Apparently Balanced Complex Chromosome Rearrangement Involving Seven Breaks and Four Chromosomes in a Healthy Female and Segregation/Recombination in Her Affected Son." Molecular Syndromology 12, no. 5 (2021): 312–20. http://dx.doi.org/10.1159/000516323.
Full textAbstract:
Duplication of the distal 1q and 4p segments are both characterized by the presence of intellectual disability/neurodevelopmental delay and dysmorphisms. Here, we describe a male with a complex chromosome rearrangement (CCR) presenting with overlapping clinical findings between these 2 syndromes. In order to better characterize this CCR, classical karyotyping, FISH, and chromosomal microarray analysis were performed on material from the patient and his parents, which revealed an unbalanced karyotype with duplications at 1q41q43 and 4p15.2p14 in the proband. The rearrangements, which were derived from a maternal balanced karyotype, included an insertion of a segment from the long to the short arm of chromosome 1, a balanced translocation involving chromosomes 14 and 18, and an insertion of a segment from the short arm of chromosome 4 into the derived chromosome 14. This study aimed to better define the clinical history and prognosis of a patient with this rare category of chromosomal aberration. Our results suggest that the frequency of CCR in the general population may be underestimated; when balanced, they may not have a phenotypic effect. Moreover, they emphasize the need for cytogenetic techniques complementary to chromosomal microarray for proper genetic counseling.
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Suzuki, Erina, Hirohito Shima, Machiko Toki, Kunihiko Hanew, Keiko Matsubara, Hiroki Kurahashi, Satoshi Narumi, Tsutomu Ogata, Tsutomu Kamimaki, and Maki Fukami. "Complex X-Chromosomal Rearrangements in Two Women with Ovarian Dysfunction: Implications of Chromothripsis/Chromoanasynthesis-Dependent and -Independent Origins of Complex Genomic Alterations." Cytogenetic and Genome Research 150, no. 2 (2016): 86–92. http://dx.doi.org/10.1159/000455026.
Full textAbstract:
Our current understanding of the phenotypic consequences and the molecular basis of germline complex chromosomal rearrangements remains fragmentary. Here, we report the clinical and molecular characteristics of 2 women with germline complex X-chromosomal rearrangements. Patient 1 presented with nonsyndromic ovarian dysfunction and hyperthyroidism; patient 2 exhibited various Turner syndrome- associated symptoms including ovarian dysfunction, short stature, and autoimmune hypothyroidism. The genomic abnormalities of the patients were characterized by array-based comparative genomic hybridization, high-resolution karyotyping, microsatellite genotyping, X-inactivation analysis, and bisulfite sequencing. Patient 1 carried a rearrangement of unknown parental origin with a 46,X,der(X)(pter→ p22.1::p11.23→q24::q21.3→q24::p11.4→pter) karyotype, indicative of a catastrophic chromosomal reconstruction due to chromothripsis/chromoanasynthesis. Patient 2 had a paternally derived isochromosome with a 46,X,der(X)(pter→ p22.31::q22.1→q10::q10→q22.1::p22.31→pter) karyotype, which likely resulted from 2 independent, sequential events. Both patients showed completely skewed X inactivation. CpG sites at Xp22.3 were hypermethylated in patient 2. The results indicate that germline complex X-chromosomal rearrangements underlie nonsyndromic ovarian dysfunction and Turner syndrome. Disease-causative mechanisms of these rearrangements likely include aberrant DNA methylation, in addition to X-chromosomal mispairing and haploinsufficiency of genes escaping X inactivation. Notably, our data imply that germline complex X-chromosomal rearrangements are created through both chromothripsis/chromoanasynthesis-dependent and -independent processes.
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Badaeva, E. D., O. S. Dedkova, G. Gay, V. A. Pukhalskyi, A. V. Zelenin, S. Bernard, and M. Bernard. "Chromosomal rearrangements in wheat: their types and distribution." Genome 50, no. 10 (October 2007): 907–26. http://dx.doi.org/10.1139/g07-072.
Full textAbstract:
Four hundred and sixty polyploid wheat accessions and 39 triticale forms from 37 countries of Europe, Asia, and USA were scored by C-banding for the presence of translocations. Chromosomal rearrangements were detected in 70 of 208 accessions of tetraploid wheat, 69 of 252 accessions of hexaploid wheat, and 3 of 39 triticale forms. Altogether, 58 types of major chromosomal rearrangements were identified in the studied material; they are discussed relative to 11 additional translocation types described by other authors. Six chromosome modifications of unknown origin were also observed. Among all chromosomal aberrations identified in wheat, single translocations were the most frequent type (39), followed by multiple rearrangements (9 types), pericentric inversions (9 types), and paracentric inversions (3 types). According to C-banding analyses, the breakpoints were located at or near the centromere in 60 rearranged chromosomes, while in 52 cases they were in interstitial chromosome regions. In the latter case, translocation breakpoints were often located at the border of C-bands and the euchromatin region or between two adjacent C-bands; some of these regions seem to be translocation “hotspots”. Our results and data published by other authors indicate that the B-genome chromosomes are involved in translocations most frequently, followed by the A- and D-genome chromosomes; individual chromosomes also differ in the frequencies of translocations. Most translocations were detected in 1 or 2 accessions, and only 11 variants showed relatively high frequencies or were detected in wheat varieties of different origins or from different species. High frequencies of some translocations with a very restricted distribution could be due to a “bottleneck effect”. Other types seem to occur independently and their broad distribution can result from selective advantages of rearranged genotypes in diverse environmental conditions. We found significant geographic variation in the spectra and frequencies of translocation in wheat: the highest proportions of rearranged genotypes were found in Central Asia, the Middle East, Northern Africa, and France. A low proportion of aberrant genotypes was characteristic of tetraploid wheat from Transcaucasia and hexaploid wheat from Middle Asia and Eastern Europe.