1051
|
|
1052
|
Affiliation(s)
- S M Gartler
- Department of Medicine, University of Washington, Seattle
| | | | | |
Collapse
|
1053
|
Affiliation(s)
- K C Cheng
- Joseph Gottstein Memorial Cancer Research Laboratory, Department of Pathology, University of Washington, Seattle 98195
| | | |
Collapse
|
1054
|
Grompe M, Rao N, Elder FF, Caskey CT, Greenberg F. 45,X/46,X,+r(X) can have a distinct phenotype different from Ullrich-Turner syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS 1992; 42:39-43. [PMID: 1339199 DOI: 10.1002/ajmg.1320420110] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We present a patient with 45,X/46,X,+r(X) mosaicism and lack of inactivation of either the normal or the ring X in the 46,X,+r(X) cells. The patient has mental retardation, syndactyly, minor facial anomalies, and a congenital heart defect. Although most patients with 45,X/46,X,+r(X) have the Ullrich-Turner syndrome, 2 previously described patients with this karyotype also had a distinct phenotype consisting of severe mental retardation, syndactyly, and abnormal face. The unusually severe phenotype in these patients was thought to be due to lack of X-inactivation of the ring X chromosome. The findings in our patient support this hypothesis.
Collapse
Affiliation(s)
- M Grompe
- Institute for Molecular Genetics, Baylor College of Medicine, Houston, Tex 77030
| | | | | | | | | |
Collapse
|
1055
|
Affiliation(s)
- S D Brown
- Department of Biochemistry and Molecular Genetics, St Mary's Hospital Medical School, London, UK
| |
Collapse
|
1056
|
Takagi N. Abnormal X-Chromosome Dosage Compensation as a Possible Cause of Early Developmental Failure in Mice. (X-chromosome inactivation/trophectoderm/imprinting/embryonic development). Dev Growth Differ 1991. [DOI: 10.1111/j.1440-169x.1991.00429.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
1057
|
Lafrenière RG, Brown CJ, Powers VE, Carrel L, Davies KE, Barker DF, Willard HF. Physical mapping of 60 DNA markers in the p21.1----q21.3 region of the human X chromosome. Genomics 1991; 11:352-63. [PMID: 1685139 DOI: 10.1016/0888-7543(91)90143-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Using a panel of human/rodent somatic cell hybrids and human lymphoblast lines segregating 18 different human X-chromosome rearrangements and deletions, we have assigned 60 DNA markers to the physical map of the X chromosome from Xp21.1 to Xq21.3. Data from Southern blot hybridization and polymerase chain reaction (PCR) amplification assign these markers to 15 primary map intervals. This provides a basis for further long-range cloning and mapping of the pericentromeric region of the X chromosome.
Collapse
Affiliation(s)
- R G Lafrenière
- Department of Genetics, Stanford University School of Medicine, California 94305
| | | | | | | | | | | | | |
Collapse
|
1058
|
Raman R, Das P. Mammalian sex chromosomes. III. Activity of pseudoautosomal steroid sulfatase enzyme during spermatogenesis in Mus musculus. SOMATIC CELL AND MOLECULAR GENETICS 1991; 17:429-33. [PMID: 1763383 DOI: 10.1007/bf01233166] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Parallel to the inactivation of the X chromosome in somatic cells of female, the male X in mammals is rendered inactive during spermatogenesis. Pseudoautosomal genes, those present on the X-Y meiotically pairable region of male, escape inactivation in female soma. It is suggested, but not demonstrated, that they may also be refractory to the inactivation signal in male germ cells. We have assayed activity of the enzyme steroid sulfatase, product of a pseudoautosomal gene, in testicular cells of the mouse and shown its presence in premeiotic, meiotic (pachytene), and postmeiotic (spermatid) cell types. It appears that, as in females, pseudoautosomal genes may escape inactivation in male germ cells also.
Collapse
Affiliation(s)
- R Raman
- Department of Zoology, Banaras Hindu University, Varanasi, India
| | | |
Collapse
|
1059
|
Abstract
Imprinting results in the preferential expression of either the maternal or the paternal allele of certain genes, and has a critical influence on the regulation of mammalian development. The identification of specific imprinted chromosomal regions and genes is being used to unravel the molecular mechanism of imprinting and the developmental significance of the non-random expression of parental alleles.
Collapse
Affiliation(s)
- M A Surani
- Department of Molecular Embryology, AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, UK
| |
Collapse
|
1060
|
Shao CS, Takagi N. Karyotypes and X chromosome inactivation in segregants of a murine X-autosome translocation, T(X;4)37H. IDENGAKU ZASSHI 1991; 66:433-47. [PMID: 1954036 DOI: 10.1266/jjg.66.433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Karyotypes and X chromosome inactivation were studied in embryos obtained from female mice carrying T(X;4)37H translocation on day 6 to 8 of gestation by a BrdU-acridine orange method. A total of 18 different karyotypes were found in 477 embryos examined: 90.0% embryos were products expected from 2:2 alternate or adjacent 1 disjunction. 3:1 and adjacent 2 disjunctions accounted for approximately 8.0% and 0.7% conceptuses, respectively. In the embryo proper of balanced T37H/ + conceptuses, inactivation was random with respect to the normal X and the larger translocation X (4x) chromosome. In all the cells with the 4x inactive, the late replication apparently did not spread to the attached autosomal portion, although black/brown coat variegation implies spreading of inactivation into the autosomal region. The X chromosome segment deprived of the inactivation center remained active in all the cells examined and it exerted deleterious effects on embryonic or fetal development. Observation in embryos having two maternally derived X chromosomes showed that they were indeed resistant to inactivation in early extraembryonic cell lineages, and two copies of active X chromosomes in the trophectoderm fatally affected embryonic development due to inability to form the extraembryonic ectoderm and ectoplacental cone from the polar trophectoderm. In unbalanced X aneuploids the X chromosomes with the deletion were preferentially inactivated due to strong selection against nullisomy X.
Collapse
Affiliation(s)
- C S Shao
- Research Center for Molecular Genetics, Hokkaido University, Sapporo, Japan
| | | |
Collapse
|
1061
|
|
1062
|
Lovell-Badge R. X marks the spot. Curr Biol 1991; 1:168-70. [PMID: 15336156 DOI: 10.1016/0960-9822(91)90222-i] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- R Lovell-Badge
- National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| |
Collapse
|
1063
|
Brockdorff N, Ashworth A, Kay GF, Cooper P, Smith S, McCabe VM, Norris DP, Penny GD, Patel D, Rastan S. Conservation of position and exclusive expression of mouse Xist from the inactive X chromosome. Nature 1991; 351:329-31. [PMID: 2034279 DOI: 10.1038/351329a0] [Citation(s) in RCA: 473] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
X-chromosome inactivation in mammals is a regulatory phenomenon whereby one of the two X chromosomes in female cells is genetically inactivated, resulting in dosage compensation for X-linked genes between males and females. In both man and mouse, X-chromosome inactivation is thought to proceed from a single cis-acting switch region or inactivation centre (XIC/Xic). In the human, XIC has been mapped to band Xq13 (ref. 6) and in the mouse to band XD (ref. 7), and comparative mapping has shown that the XIC regions in the two species are syntenic. The recently described human XIST gene maps to the XIC region and seems to be expressed only from the inactive X chromosome. We report here that the mouse Xist gene maps to the Xic region of the mouse X chromosome and, using an interspecific Mus spretus/Mus musculus domesticus F1 hybrid mouse carrying the T(X;16)16H translocation, show that Xist is exclusively expressed from the inactive X chromosome. Conservation between man and mouse of chromosomal position and unique expression exclusively from the inactive X chromosome lends support to the hypothesis that XIST and its mouse homologue are involved in X-chromosome inactivation.
Collapse
Affiliation(s)
- N Brockdorff
- Section of Comparative Biology, MRC Clinical Research Centre, Harrow, UK
| | | | | | | | | | | | | | | | | | | |
Collapse
|
1064
|
Borsani G, Tonlorenzi R, Simmler MC, Dandolo L, Arnaud D, Capra V, Grompe M, Pizzuti A, Muzny D, Lawrence C, Willard HF, Avner P, Ballabio A. Characterization of a murine gene expressed from the inactive X chromosome. Nature 1991; 351:325-9. [PMID: 2034278 DOI: 10.1038/351325a0] [Citation(s) in RCA: 414] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In mammals, equal dosage of gene products encoded by the X chromosome in male and female cells is achieved by X inactivation. Although X-chromosome inactivation represents the most extensive example known of long range cis gene regulation, the mechanism by which thousands of genes on only one of a pair of identical chromosomes are turned off is poorly understood. We have recently identified a human gene (XIST) exclusively expressed from the inactive X chromosome. Here we report the isolation and characterization of its murine homologue (Xist) which localizes to the mouse X inactivation centre region and is the first murine gene found to be expressed from the inactive X chromosome. Nucleotide sequence analysis indicates that Xist may be associated with a protein product. The similar map positions and expression patterns for Xist in mouse and man suggest that this gene may have a role in X inactivation.
Collapse
Affiliation(s)
- G Borsani
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
1065
|
Affiliation(s)
- M F Lyon
- MRC Radiobiology Unit, Chilton, Didcot, UK
| |
Collapse
|
1066
|
Brown CJ, Lafreniere RG, Powers VE, Sebastio G, Ballabio A, Pettigrew AL, Ledbetter DH, Levy E, Craig IW, Willard HF. Localization of the X inactivation centre on the human X chromosome in Xq13. Nature 1991; 349:82-4. [PMID: 1985270 DOI: 10.1038/349082a0] [Citation(s) in RCA: 279] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
X-chromosome inactivation results in the strictly cis-limited inactivation of many but not all genes on one of the two X chromosomes during early development in somatic cells of mammalian females. One feature of virtually all models of X inactivation is the existence of an X-inactivation centre (XIC) required in cis for inactivation to occur. This concept predicts that all structurally abnormal X chromosomes capable of being inactivated have in common a defineable region of the X chromosome. Here we report an analysis of several such rearranged human X chromosomes and define a minimal region of overlap. The results are consistent with models invoking a single XIC and provide a molecular foothold for cloning and analysing the XIC region. One of the markers that defines this region is the XIST gene, which is expressed specifically from inactive, but not active, X chromosomes. The localization of the XIST gene to the XIC region on the human X chromosome implicates XIST in some aspect of X inactivation.
Collapse
Affiliation(s)
- C J Brown
- Department of Genetics, Stanford University School of Medicine, California 94305
| | | | | | | | | | | | | | | | | | | |
Collapse
|
1067
|
|
1068
|
Sefton L, Arnaud D, Goodfellow PN, Simmler MC, Avner P. Characterization of the central region containing the X-inactivation center and terminal region of the mouse X chromosome using irradiation and fusion gene transfer hybrids. Mamm Genome 1991; 2:21-31. [PMID: 1543901 DOI: 10.1007/bf00570437] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The irradiation and fusion gene transfer (IFGT) procedure provides a means of isolating subchromosomal fragments for use in the mapping of loci and for cloning probes from a particular area of a chromosome. Using this procedure, two large panels of somatic cell hybrids that contain mouse X Chromosome (Chr) fragments have been generated. These hybrid panels were generated by irradiating the monochromosomal mouse-hamster hybrid HYBX, which retains the mouse X Chr, with either 10 K or 50 K rads of X-irradiation followed by fusion with a recipient Chinese hamster cell line. IFGT hybrids retaining mouse material were generated at high frequency. These hybrids were used to orient loci in the X-inactivation center region that had not been resolvable in our interspecies backcross panel and also to map, within the terminal region of the X Chr, repeat elements detected by the probe p15-4. These hybrids not only complement existing interspecies meiotic mapping panels for the detailed analysis of specific regions of particular chromosomes, but also provide a potential source of material for chromosome-specific probe isolation.
Collapse
Affiliation(s)
- L Sefton
- Human Molecular Genetics Laboratory, Imperial Cancer Research Fund, London, UK
| | | | | | | | | |
Collapse
|