caa a22 4500 469044748 CHVBK 20180323132821.0 cr unu---uuuuu 170328e19920701xx s 000 0 eng 10.1007/BF01799608 doi (NATIONALLICENCE)springer-10.1007/BF01799608 Monk M. MRC Mammalian Development Unit, 4 Stephenson Way, NW1 2HE, London, UK aut The X chromosome in development in mouse and man [Elektronische Daten] [M. Monk] Summary: In mammals, dosage compensation for X-linked genes between males and females is achieved by the inactivation of one of the X chromosomes in females. The inactivation event occurs early in development in all cells of the female mouse embryo and is stable and heritable in somatic cells. However, in the primordial germ cells, reactivation occurs around the time of meiosis. Owing to random inactivation in somatic cells, all female mice and humans are mosaic for X-linked gene function. Variable mosaicism can result in expression of disease in human females heterozygous for an X-linked gene defect. In the extra-embryonic lineages of female mouse embryos, and in the somatic cells of female marsupials, the paternally inherited X chromosome is preferentially inactivated. The X chromosomes in the egg and sperm must be differentially marked or imprinted, so that they are distinguished by the inactivation mechanism in these tissues. Initiation of inactivation of an entire X chromosome appears to spread from a single X-inactivation centre and may involve the recently discovered gene,XIST, which is expressed only from the inactive X chromosome. The maintenance of inactivation of certain household genes on the inactive X chromosome involves methylation of CpG islands in their 5' regions. Critical CpG sites are methylated at, or very close to, the time of inactivation in development. The mouse and the human X chromosomes carry the same genes but their arrangement is different and there are some genes in the pairing segment and elsewhere on the human X chromosome which can escape inactivation. Regions of homology between the mouse and human X chromosomes allow prediction of the map positions of homologous genes and provide mouse models of genetic disease in the human. SSIEM and Kluwer Academic Publishers, 1992 Journal of Inherited Metabolic Disease Kluwer Academic Publishers 15/4(1992-07-01), 499-513 0141-8955 15:4<499 1992 15 10545 https://doi.org/10.1007/BF01799608 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF01799608 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Monk M. MRC Mammalian Development Unit, 4 Stephenson Way, NW1 2HE, London, UK aut NATIONALLICENCE 773 0- Journal of Inherited Metabolic Disease Kluwer Academic Publishers 15/4(1992-07-01), 499-513 0141-8955 15:4<499 1992 15 10545 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer