| 1. |
- Castiglione, Alessandro, 1976-, et al.
(författare)
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Karyotype-phenotype correlation in partial trisomies of the short arm of chromosome 6 : a family case report and review of the literature
- 2013
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Ingår i: Cytogenetic and Genome Research. - Basel : S. Karger. - 1424-8581 .- 1424-859X. ; 141:4, s. 243-259
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Forskningsöversikt (refereegranskat)abstract
- The first child (proband) of nonconsanguineous Caucasian parents underwent genetic investigation because she was affected with congenital choanal atresia, heart defects and kidney hyposplasia with mild transient renal insufficiency. The direct DNA sequencing after PCR of the CHD7 gene, which is thought to be responsible for approximately 60-70% of the cases of CHARGE syndrome/association, found no mutations. The cytogenetic analysis (standard GTG banding karyotype) revealed the presence of extrachromosomal material on 10q. The chromosome analysis was completed with array CGH (30 kb resolution), MLPA and FISH, which allowed the identification of three 6p regions (6p.25.3p23 × 3): 2 of these regions are normally located on chromosome 6, and the third region is translocated to the long arm of chromosome 10. The same chromosomal rearrangement was subsequently found in the father, who was affected with congenital ptosis and progressive hearing loss, and in the proband's sister, the second child, who presented at birth with choanal atresia and congenital heart defects. The mutated karyotypes, which were directly inherited, are thought to be responsible for a variable phenotype, including craniofacial dysmorphisms, choanal atresia, congenital ptosis, sensorineural hearing loss, heart defects, developmental delay, and renal dysfunction. Nevertheless, to achieve a complete audiological assessment of the father, he underwent further investigation that revealed an increased level of the coagulation factor XIII (300% increased activity), fluctuating levels of fibrin D-dimer degradation products (from 296 to 1,587 ng/ml) and a homoplasmic mitochondrial DNA mutation: T961G in the MTRNR1 (12S rRNA) gene. He was made a candidate for cochlear implantation. Preoperative high-resolution computed tomography and magnetic resonance imaging of the temporal bone revealed the presence of an Arnold-Chiari malformation type I. To the best of our knowledge, this study is the second report on partial 6p trisomy that involves the 10q terminal region. Furthermore, we report the first case of documented Arnold-Chiari malformation type I and increased factor XIII activity associated with 6p trisomy. We present a comprehensive report of the familial cases and an exhaustive literature review.
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| 2. |
- Gisselsson Nord, David
(författare)
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Mechanisms of Whole Chromosome Gains in Tumors - Many Answers to a Simple Question.
- 2011
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Ingår i: Cytogenetic and Genome Research. - : S. Karger AG. - 1424-859X .- 1424-8581. ; 133, s. 190-201
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Tidskriftsartikel (refereegranskat)abstract
- Whole chromosome gain is the most common type of gross genomic abnormality observed in human tumors. It is particularly frequent in lympho-haematopoietic and embryonic neoplasms, where trisomies and tetrasomies are typically present together with few or no other cytogenetic imbalances, resulting in hyperdiploid chromosome numbers. Despite the high prevalence of whole chromosome gains in neoplastic cells, their mechanism of origin remains disputed. Here, 4 potential models for the generation of whole chromosome gains are reviewed: (1) loss of chromosomes from the tetraploid level, (2) sequential sister chromatid non-disjunction, (3) multipolar mitosis coupled to sister chromatid non-disjunction, and (4) multipolar mitosis coupled to incomplete cytokinesis. Each of these mechanisms may in theory result in the generation of hyperdiploid neoplastic clones, but none of them were single-handedly able to reproduce the scenario of chromosome copy number alterations in tumors when cell populations resulting from these models were simulated in silico and compared to published cytogenetic data. To develop models for the generation of whole chromosome gains further, it is critical to improve our knowledge of the principles of clonal selection in tumors and of the baseline rate of chromosome segregation errors in human cells. To illustrate this, a model combining multipolar mitosis coupled to incomplete cytokinesis with a low rate of baseline sister chromatid non-disjunction was shown readily to reproduce copy number distributions in hyperdiploid karyotypes from human tumors.
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| 3. |
- Hulten, M A., et al.
(författare)
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Trisomy 21 Mosaicism: We May All Have a Touch of Down Syndrome
- 2013
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Ingår i: Cytogenetic and Genome Research. - : Karger. - 1424-8581 .- 1424-859X. ; 139:3, s. 189-192
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Tidskriftsartikel (refereegranskat)abstract
- Ever increasing sophistication in the application of new analytical technology has revealed that our genomes are much more fluid than was contemplated only a few years ago. More specifically, this concerns interindividual variation in copy number (CNV) of structural chromosome aberrations, i.e. microdeletions and microduplications. It is important to recognize that in this context, we still lack basic knowledge on the impact of the CNV in normal cells from individual tissues, including that of whole chromosomes (aneuploidy). Here, we highlight this challenge by the example of the very first chromosome aberration identified in the human genome, i.e. an extra chromosome 21 (trisomy 21, T21), which is causative of Down syndrome (DS). We consider it likely that most, if not all, of us are T21 mosaics, i.e. everyone carries some cells with an extra chromosome 21, in some tissues. In other words, we may all have a touch of DS. We further propose that the occurrence of such tissue-specific T21 mosaicism may have important ramifications for the understanding of the pathogenesis, prognosis and treatment of medical problems shared between people with DS and those in the general non-DS population.
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| 4. |
- Moreno Romero, Jordi, et al.
(författare)
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Changes in Histone Methylation and Acetylation during Microspore Reprogramming to Embryogenesis Occur Concomitantly with BnHKMT and BnHAT Expression and Are Associated with Cell Totipotency, Proliferation, and Differentiation in Brassica napus
- 2014
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Ingår i: Cytogenetic and Genome Research. - : S. Karger AG. - 1424-8581 .- 1424-859X. ; 143, s. 209-218
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Tidskriftsartikel (refereegranskat)abstract
- In response to stress treatments, microspores can be reprogrammed to become totipotent cells that follow an embryogenic pathway producing haploid and double-haploid embryos which are important biotechnological tools in plant breeding. Recent studies have revealed the involvement of DNA methylation in regulating this process, but no information is available on the role of histone modifications in microspore embryogenesis. Histone modifications are major epigenetic marks controlling gene expression during plant development and in response to environmental changes. Lysine methylation of histones, accomplished by histone lysine methyltransferases (HKMTs), can occur on different lysine residues, with histone H3K9 methylation being mainly associated with transcriptionally silenced regions. In contrast, histone H3 and H4 acetylation is carried out by histone acetyltransferases (HATs) and is associated with actively transcribed genes. In this work, we analyzed 3 different histone epigenetic marks: dimethylation of H3K9 (H3K9me2) and acetylation of H3 and H4 (H3Ac and H4Ac) during microspore embryogenesis in Brassica napus by Western blot and immunofluorescence assays. The expression patterns of histone methyltransferase BnHKMT and histone acetyltransferase BnHAT genes have also been analyzed by qPCR. Our results revealed different spatial and temporal distribution patterns for methylated and acetylated histone variants during microspore embryogenesis and their similarity with the expression profiles of BnHKMT and BnHAT, respectively. The data presented suggest the participation of H3K9me2 and HKMT in embryo cell differentiation and heterochromatinization events, whereas H3Ac, H4Ac, and HAT would be involved in transcriptional activation, totipotency, and proliferation events during cell reprogramming and embryo development. (C) 2014 S. Karger AG, Basel
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| 5. |
- Paulsson, Kajsa
(författare)
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Genomic Heterogeneity in Acute Leukemia.
- 2013
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Ingår i: Cytogenetic and Genome Research. - : S. Karger AG. - 1424-859X .- 1424-8581. ; 139:3, s. 174-180
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Tidskriftsartikel (refereegranskat)abstract
- Acquired genetic aberrations are the underlying cause of leukemogenesis in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). The karyotypes of AML and ALL cases are generally quite simple as seen by chromosome banding analysis, with few genetic changes and a limited number of subclones. However, investigations using fluorescence in situ hybridization, loss of heterozygosity analysis, single-nucleotide polymorphism arrays, and, most recently, massively parallel sequencing have challenged this view. In particular, comparison of diagnostic and relapse samples, modeling in transgenic mice, and whole-exome and whole-genome sequencing have indicated that widespread genomic heterogeneity, which is masked by a dominant clone, may be present in AML and ALL. In the present review, our current knowledge of genomic heterogeneity in acute leukemia is summarized.
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| 6. |
- Stenberg, Per, et al.
(författare)
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Meiosis and Its Deviations in Polyploid Animals
- 2013
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Ingår i: Cytogenetic and Genome Research. - : S. Karger AG. - 1424-8581 .- 1424-859X. ; 140:2-4, s. 185-203
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Tidskriftsartikel (refereegranskat)abstract
- We review the different modes of meiosis and its deviations encountered in polyploid animals. Bisexual reproduction involving normal meiosis occurs in some allopolyploid frogs with variable degrees of polyploidy. Aberrant modes of bisexual reproduction include gynogenesis, where a sperm stimulates the egg to develop. The sperm may enter the egg but there is no fertilization and syngamy. In hybridogenesis, a genome is eliminated to produce haploid or diploid eggs or sperm. Ploidy can be elevated by fertilization with a haploid sperm in meiotic hybridogenesis, which elevates the ploidy of hybrid offspring such that they produce diploid gametes. Polyploids are then produced in the next generation. In kleptogenesis, females acquire full or partial genomes from their partners. In pre-equalizing hybrid meiosis, one genome is transmitted in the Mendelian fashion, while the other is transmitted clonally. Parthenogenetic animals have a very wide range of mechanisms for restoring or maintaining the mother's ploidy level, including gamete duplication, terminal fusion, central fusion, fusion of the first polar nucleus with the product of the first division, and premeiotic duplication followed by a normal meiosis. In apomictic parthenogenesis, meiosis is replaced by what is effectively mitotic cell division. The above modes have different evolutionary consequences, which are discussed. See also the sister article by Grandont et al. in this themed issue.
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| 7. |
- Werlemark, Gun, et al.
(författare)
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High Penetrance of a Pan-Canina Type rDNA Family in Intersection Rosa Hybrids Suggests Strong Selection of Bivalent Chromosomes in the Section Caninae
- 2014
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Ingår i: Cytogenetic and Genome Research. - : S. Karger AG. - 1424-8581 .- 1424-859X. ; 143, s. 104-113
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Tidskriftsartikel (refereegranskat)abstract
- All dogroses (Rosa sect. Caninae) are characterized by the peculiar canina meiosis in which genetic material is unevenly distributed between female and male gametes. The pan-canina rDNA family (termed beta) appears to be conserved in all dogroses analyzed so far. Here, we have studied rDNAs in experimental hybrids obtained from open pollination of F1 plants derived from 2 independent intersectional crosses between the pentaploid dogrose species (2n = 5x = 35) Rosa rubiginosa as female parent (producing 4x egg cells due to the unique asymmetrical canina meiosis) and the tetraploid (2n = 4x = 28) garden rose R. hybrida 'Andre Brichet' as male parent (producing 2x pollen after normal meiosis). We analyzed the structure of rDNA units by molecular methods [CAPS and extensive sequencing of internal transcribed spacers (ITS)] and determined the number of loci on chromosomes by FISH. FISH showed that R. rubiginosa and 'Andre Brichet' harbored 5 and 4 highly heteromorphic rDNA loci, respectively. In the second generation of hybrid lines, we observed a reduced number of loci (4 and 5 instead of the expected 6). In R. rubiginosa and 'Andre Brichet', 2-3 major ITS types were found which is consistent with a weak homogenization pressure maintaining high diversity of ITS types in this genus. In contrast to expectation (the null hypothesis of Mendelian inheritance of ITS families), we observed reduced ITS diversity in some individuals of the second generation which might derive from self-fertilization or from a backcross to R. rubiginosa. In these individuals, the pan-canina beta family appeared to be markedly enriched, while the paternal families were lost or diminished in copies. Although the mechanism of biased meiotic transmission of certain rDNA types is currently unknown, we speculate that the bivalent-forming chromosomes carrying the beta rDNA family exhibit extraordinary pairing efficiency and/or are subjected to strong selection in Caninae polyploids. (C) 2014 S. Karger AG, Basel
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