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PubMed2001

Maternal sex chromosome non-disjunction: evidence for X chromosome-specific risk factors.

Human trisomy is attributable to many different mechanisms and the relative importance of each mechanism is highly chromosome specific. The association between altered recombination and maternal non-disjunction is well documented: reductions in recombination have been reported for maternal meiosis I (MI) errors involving chromosomes 15, 16, 18 and 21 and increased recombination has been reported for meiosis II (MII) errors involving chromosome 21. We therefore investigated maternal X chromosome non-disjunction, to determine whether the effects of recombination are unique to the X chromosome or similar to any of the autosomes thus far studied. We genotyped 45 47,XXX females and 95 47,XXY males of maternal origin. Our results demonstrate that 49% arose during MI, 29% during MII and 16% were postzygotic events; a further 7% were meiotic but could not be assigned as either MI or MII because of recombination at the centromere. Among the MI cases, a majority (56%) had no detectable transitions and so absent recombination is an important factor for X chromosome non-disjunction. However, similar to trisomy 15 and unlike trisomy 21, we observed a significant increase in the mean maternal age of transitional MI errors compared with nullitransitional cases. In our studies of MII errors, recombination appeared normal and there was no obvious effect of maternal age, distinguishing our results from MII non-disjunction of chromosomes 18 or 21. Thus, surprisingly, the risk factors associated with both MI and MII non-disjunction appear to be different for virtually every chromosome that has been adequately studied.

Adult↗
PubMed1994

Integration of physical, genetic and cytogenetic maps of human chromosome 7: isolation and analysis of yeast artificial chromosome clones for 117 mapped genetic markers.

An important goal for the human genome project is to assemble fully integrated physical, genetic and cytogenetic maps for each human chromosome. Towards that end, we have isolated yeast artificial chromosome (YAC) clones containing 117 of the 119 genetic markers that constitute a recently constructed, detailed genetic map of human chromosome 7. Analysis of these clones reveals numerous examples where adjacent genetic markers have been physically connected, either in individual YACs or in multi-YAC contigs. At present, the 117 genetic markers are contained in fewer than 80 YAC contigs, with most of these contigs uniquely ordered relative to one another based on the genetic map positions of the corresponding markers. These YACs and YAC contigs are estimated to contain approximately 60-85% of the DNA from human chromosome 7. YACs representing 36 genetic markers were mapped by fluorescence in situ hybridization (FISH) to metaphase chromosomes, allowing assignment of these genetic markers to cytogenetic bands along chromosome 7 and placement of the centromere within the genetic map. Together, these studies provide genetically and cytogenetically anchored YAC clones covering the majority of chromosome 7 that will be useful both for the positional cloning of genes and as a framework for assembling a complete YAC-based physical map of the chromosome.

Chromosome Mapping↗
PubMed1995

Integration of physical, breakpoint and genetic maps of chromosome 22. Localization of 587 yeast artificial chromosomes with 238 mapped markers.

Detailed physical maps of the human genome are important resources for the identification and isolation of disease genes and for studying the structure and function of the genome. We used data from STS content mapping of YACs and natural and induced chromosomal breakpoints to anchor contigs of overlapping yeast artificial chromosome (YAC) clones spanning extensive regions of human chromosome 22. The STSs were assigned to specific regions (bins) on the chromosome using cell lines from a somatic hybrid mapping panel defining a maximum of 25 intervals. YAC libraries were screened by PCR amplification of hierarchical pools of yeast DNA with 238 markers, and a total of 587 YAC clones were identified. These YACs were assembled into contigs based upon their shared STS content using a simulated annealing algorithm. Fifteen contigs, containing between 2 and 74 STSs were assembled, and ordered along the chromosome based upon the cytogenetic breakpoint, meiotic and PFG maps. Additional singleton YACs were assigned to unique chromosomal bins. These ordered YAC contigs will be useful for identifying disease genes and chromosomal breakpoints by positional cloning and will provide the foundation for higher resolution physical maps for large scale sequencing of the chromosome.

Chromosome Mapping↗
PubMed2006

CGH of microdissected Kaposi's sarcoma lesions reveals recurrent loss of chromosome Y in early and additional chromosomal changes in late tumour stages.

BACKGROUND: It is still unclear if Kaposi's sarcoma (KS) is a monoclonal cell proliferation or a polyclonal, hyperplastic, reactive process. Reports on KS cytogenetics are few and restricted to late stage disease and cell lines. METHOD: We analysed 27 KS, early and late, AIDS related (AKS) and endemic (EKS) by laser microdissection, global DNA amplification and comparative genomic hybridization (CGH). RESULT: Loss of Y chromosome was detected in 20/23 male KS, which was the only recurrent chromosomal aberration in all nine male early (patch) KS. Only one patch EKS showed in addition to the Y loss a loss of Xq. Late (nodular) AKS and EKS showed recurrent copy number changes in chromosomes 16, 17, 21, X and Y, as well as other random changes. The loss of chromosome 16, 17 and Y was confirmed by interphase fluorescence in situ hybridization (FISH) on paraffin sections. EKS showed a higher number of chromosomal abnormalities than AKS, indicating that rapid growth of AKS is less dependent on genetic changes than is EKS, possibly because of the immunosuppressed host environment in AKS. CONCLUSION: Clonal loss of chromosome Y was detected in all early male KS, while additional chromosomal aberrations appeared during development to late KS. This increase in chromosomal abnormalities during tumour growth indicates genetic instability and the selection of survival cell clones establishing late, aggressive sarcoma growth. Our data support the view that KS (in males) develops into a clonal tumour yet initially is a hyperplastic reactive cell proliferation.

Acquired Immunodeficiency Syndrome↗
PubMed1995

A high-fidelity physical map of human chromosome 21q in yeast artificial chromosomes.

Understanding of the human genome has been advanced significantly by the development of large DNA fragment libraries. To create a map of chromosome 21q that integrates the physical, cytogenetic, and linkage maps, we have characterized a subset of 127 chromosome 21 yeast artificial chromosome (YAC) clones for size, by pulsed field gel electrophoresis, for chimerism and cytogenetic location, by fluorescence in situ hybridization (FISH), and for sequence-tagged sites (STS) content, by PCR. It was found that 54% generated unique map locations on chromosome 21, and 45% detected sites on other chromosomes, of which 33% likely represented true chimerism. Using a simple algorithm, the data from nonchimeric clones have been combined to generate a size-corrected minimal tiling pathway including 58 chromosome 21q YACs that represent approximately 33 Mb and include 9 gaps. To confirm the resulting order and relationship to the cytogenetic map, the breakpoints from 23 cell lines partially aneuploid for chromosome 21 have been analyzed by quantitative Southern blot dosage analysis and FISH with a subset of the markers. As one way of investigating the relationship of the genetic to the physical map, the genetic map was superimposed on the physical map using a subset of well-defined markers common to both. The results suggest potential hot spots for recombination and/or gaps in the physical map. This integrated map will facilitate the search for the genes responsible for the Down syndrome phenotypes and provide a better understanding of genome organization and chromosome structure.

Aneuploidy↗
PubMed2004

Comparative mapping of human chromosome 10 to pig chromosomes 10 and 14.

Identification of predictive markers in QTL regions that impact production traits in commercial populations of swine is dependent on construction of dense comparative maps with human and mouse genomes. Chromosomal painting in swine suggests that large genomic blocks are conserved between pig and human, while mapping of individual genes reveals that gene order can be quite divergent. High-resolution comparative maps in regions affecting traits of interest are necessary for selection of positional candidate genes to evaluate nucleotide variation causing phenotypic differences. The objective of this study was to construct an ordered comparative map of human chromosome 10 and pig chromosomes 10 and 14. As a large portion of both pig chromosomes are represented by HSA10, genes at regularly spaced intervals along this chromosome were targeted for placement in the porcine genome. A total of 29 genes from human chromosome 10 were mapped to porcine chromosomes 10 (SSC10) and 14 (SSC14) averaging about 5 Mb distance of human DNA per marker. Eighteen genes were assigned by linkage in the MARC mapping population, five genes were physically assigned with the IMpRH mapping panel and seven genes were assigned on both maps. Seventeen genes from human 10p mapped to SSC10, and 12 genes from human 10q mapped to SSC14. Comparative maps of mammalian species indicate that chromosomal segments are conserved across several species and represent syntenic blocks with distinct breakpoints. Development of comparative maps containing several species should reveal conserved syntenic blocks that will allow us to better define QTL regions in livestock.

Animals↗
PubMed2001

Alteration of chromosome numbers by generation of minichromosomes -- is there a lower limit of chromosome size for stable segregation?

Practical applications of minichromosomes, generated by de novo composition or by truncation of natural chromosomes, rely on stable transmission of these chromosomes. Functional centromeres, telomeres and replication origins are recognized as prerequisites for minichromosome stability. However, it is not yet clear whether, and if yes, to what degree the chromatin content has a qualitative or quantitative impact on stable chromosome transmission. A small translocation chromosome, which arose after X-irradiation of a reconstructed field bean karyotype, comprised approximately 5% of the haploid metaphase complement and was found to consist of three pieces of duplicated chromatin and a wild-type centromere. This chromosome was stably transmitted through all meristematic and pollen grain mitoses but was frequently lost during meiosis (66% loss in hemizygous and 33% in homozygous condition). This minichromosome was only a little smaller than stably segregating translocation chromosomes (comprising approximately 6% of the genome) of a euploid field bean karyotype. The duplications specific for this minichromosome did not influence meiotic segregation when associated with non-duplicated chromatin of other chromosomes. In comparison with minichromosomes of other species, the possibility of a lower size limit for a stable chromosome transmission must therefore be considered which might be based, for instance, on insufficient lateral support of centromeres or on insufficient bivalent stability due to the incapability of chiasma formation.

Animals↗
PubMed2002

Molecular-cytogenetic analysis reveals sequence differences between the sex chromosomes of Oreochromis niloticus: evidence for an early stage of sex-chromosome differentiation.

Sex determination in the Nile tilapia, Oreochromis niloticus, is primarily genetic, with XX females and XY males. A candidate sex-determining region in the terminal region of the largest chromosome pair has been identified by analysis of meiotic chromosomes. This region shows an inhibition of pairing and synapsis in the XY genotype, but not in XX or YY genotypes, suggesting that recombination is inhibited. Here we show that chromosome microdissection and subsequent amplification by degenerate oligonucleotide-primed PCR (DOP-PCR) can be used to produce in situ hybridization probes to this largest pair of O. niloticus chromosomes. Furthermore, analysis of the comparative hybridization of X and Y chromosome-derived probes to different genotypes provides the first demonstration that sequence differences exist between the sex chromosomes of O. niloticus. This provides further support for the theory that this chromosome pair is related to sex determination and further suggests that the sex chromosomes are at a very early stage of divergence.

Animals↗
PubMed2001

Role of chromosomal passenger complex in chromosome segregation and cytokinesis.

Chromosomal passenger proteins associate with chromosomes early in mitosis and transfer to the spindle at ana/telophase. Recent results show that aurora B/AIM-1 (aurora and Ipl1-like midbody-associated protein kinase), which is responsible for mitotic histone H3 phosphorylation, INCENP (Inner Centromere protein) and Survivin/BIR are in a macromolecular complex as novel chromosomal passenger proteins. Aurora B/AIM-1 can bind to Survivin and the C-terminal region of INCENP, respectively, and colocalizes with both proteins to the centromeres, midzone and midbody. Disruption of either aurora B/AIM-1 or INCENP function leads to sever defects in chromosome segregation and cytokinesis. Moreover, the formation of the central spindle through anaphase to cytokinesis is also disrupted severely. These data suggest that chromosomal passenger complex is required for proper chromosome segregation by phosphorylating histone H3, and cytokinesis by ensuring the correct assembly of the midzone and midbody microtubule. Chromosomal passenger protein complex may couple chromosome segregation with cytokinesis.

Animals↗
PubMed1985

Consistent deficiencies of chromosome 18 and of the short arm of chromosome 17 in eleven cases of human large bowel cancer: a possible recessive determinism.

Cytogenetic study of 11 cases of colorectal carcinoma was performed after R-banding. In all instances, there was a rearrangement involving chromosome 17 in its juxtacentromeric region, leading to the loss of its short arm. There was also a relative lack of chromosome 18, unrelated to a rearrangement of this chromosome in all but one case. Other anomalies, involving chromosomes 1 and 8 among others, were frequently but not systematically observed. The consistent lack of chromosome 18 and of the short arm of chromosome 17, leading to a complete or partial monosomy of these chromosomes in near diploid cells suggests that the passage to the hemizygous status of recessive genes carried by these chromosomes may play an important role in the development of colorectal carcinoma.

Adult↗
PubMed1993

Schizophrenia-associated chromosome 11q21 translocation: identification of flanking markers and development of chromosome 11q fragment hybrids as cloning and mapping resources.

Genetic linkage, molecular analysis, and in situ hybridization have identified TYR and D11S388 as markers flanking the chromosome 11 breakpoint in a large pedigree where a balanced translocation, t(1;11)(q43;q21), segregates with schizophrenia and related affective disorders. Somatic cell hybrids, separating the two translocation chromosomes from each other and from the normal homologues, have been produced with the aid of immunomagnetic sorting for chromosome 1- and chromosome 11-encoded cell-surface antigens. The genes for two of these antigens map on either side of the 11q breakpoint. Immunomagnetic bead sorting was also used to isolate two stable X-irradiation hybrids for each cell-surface antigen. Each hybrid carries only chromosome 11 fragments. Translocation and X-irradiation hybrids were analyzed, mainly by PCR, for the presence of 19 chromosome 11 and 4 chromosome 1 markers. Ten newly designed primers are reported. The X-irradiation hybrids were also studied cytogenetically, for human DNA content, by in situ Cot1 DNA hybridization and by painting the Alu-PCR products from these four lines back onto normal human metaphases. The generation of the translocation hybrids and of the chromosome 11q fragment hybrids is a necessary preliminary to determining whether a schizophrenia-predisposition gene SCZD2 is encoded at this site.

Animals↗
PubMedDate not supplied

[Cytogenetic analysis of sister chromosome sets in the second polar body and in pronuclei of unicellular mouse embryos. I. Frequency and origin of aneuploidy in embryos heterozygous for the reciprocal chromosome translocation T[14;15]6Ca].

We carried out a cytogenetic study of ovulating oocytes and unicellular embryos, heterozygous by reciprocal chromosomal translocation T[14;15]6Ca. Okadaic acid was used to induce premature condensation of the interphase chromosomes in the embryos, and the number of G1 chromosomes was counted in the second polar body and pronuclei. It was shown that cytogenetic analysis of the sister chromosomal sets adequately determines the frequency of chromosomal segregation errors during oocyte meioses I and II. Trisomy and monosomy were observed in 36.2% embryos, while 2.2% featured tetrasomy or double monosomy. Errors of the first meiotic division caused aneuploidy in 28.5% embryos; trisomy and monosomy resulted from the homologs non-disjunction and chromatid presegregation in 17.6 and 10.9%, respectively. Numeral chromosomal aberrations in 4.1% of the embryos resulted from abnormal chromosomal segregation during oocyte meiosis II, while paternal chromosomal aberrations were found in 5.8% embryos. The main advantage of the proposed method is not only the higher accuracy in estimating the meiotic error frequency, but also the possibility to trace the origin of aneuploidy in mammalian embryos.

Aneuploidy↗
PubMed2005

A high-resolution comparative map between pig chromosome 17 and human chromosomes 4, 8, and 20: identification of synteny breakpoints.

We report on the construction of a high-resolution comparative map of porcine chromosome 17 (SSC17) focusing on evolutionary breakpoints with human chromosomes. The comparative map shows high homology with human chromosome 20 but suggests more limited homologies with other human chromosomes. SSC17 is of particular interest in studies of chromosomal organization due to the presence of QTLs that affect meat quality and carcass composition. A total of 158 pig ESTs available in databases or developed by the Sino-Danish Pig Genome Sequencing Consortium were mapped using the INRA-University of Minnesota porcine radiation hybrid panel. The high-resolution map was further anchored by fluorescence in situ hybridization. This study confirmed the extensive conservation between SSC17 and HSA20 and enabled the gene order to be determined. The homology of the SSC17 pericentromeric region was extended to other human chromosomes (HSA4, HSA8) and the chromosomal breakpoint boundaries were accurately defined. In total 15 breakpoints were identified.

Animals↗
PubMed1988

Complex chromosomal rearrangement involving chromosomes 11, 13 and 21.

In the present report we describe a complex chromosomal rearrangement, resulting in a distal 11p monosomy, in a 7-month-old severely retarded girl with a non-specific phenotype. In this complex chromosomal rearrangement chromosomes 11, 13 and 21 are involved in the translocation of the long arm of chromosome 21 on the short arm of chromosome 13 and translocation of the short arm and satellites of chromosome 21 on the short arm of chromosome 11.

Chromosome Aberrations↗