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Human Genome News Archive Edition

Human Genome News, May 1991; 3(1)

Second X Chromosome Workshop

The second X Chromosome Workshop, funded by the U.K. Medical Research Council, was held at St. Catherine's College, Oxford, on January 5-7. Some 70 participants heard short presentations of new mapping data and then divided into four groups to construct physical and genetic maps and to compile a table. The table indicates where contigs are available and which laboratories have yeast artificial chromosome (YAC) clones of interest. Copies of the table, which has been submitted to Genomics, are available on request from Kay Davies.

Although a complete genetic map of the X chromosome has been available for some time, it was based largely on markers with restricted information potential. Several microsatellite markers along the chromosome now indicate that a higher-resolution map will soon be available; 12 Mb of the short-arm telomere have been mapped by pulsed-field electrophoresis [Christine Petit (Institut Pasteur); Andrea Ballabio (Instituto G. Gaslini)], and an equivalent map has been constructed for the long-arm telomere [Anne-Marie Poutska (German Cancer Research Center); Hans Lehrach (Imperial Cancer Research Fund {ICRF})]. Researchers are currently assembling YAC contigs to complement these studies.

Important contributions were made to the characterization of sequences expressed from inactive X chromosomes and mapped in the region containing the putative inactivation center [Ballabio; Huntington Willard (Stanford University School of Medicine); Philip Avner (Institut Pasteur)]. Methylation differences close to the fragile site in individuals expressing the phenotype were separ ately reported by the laboratories of Jean-Louis Mandel (Institute National de la Sante et de la Recherche Medicale) and Davies.

Mapping resources for the X chromosome were discussed. Several groups are screening YAC libraries to complete a contig map of the chromosome [Thomas Caskey (Baylor College of Medicine); Centre d'Etude du Polymorphisme Humain; Lehrach; Robert Nussbaum (University of Pennsylvania School of Medicine); David Schlessinger (Washington University School of Medicine); Michele D'Urso (International Institute of Genetics and Biophysics)]. Ordered cosmid libraries are proving a valuable resource [Lehrach; David Bentley (Guy's Hospital)]. The chromosome was divided into intervals by well-characterized somatic cell hybrid breakpoints, which may be used as common reference points on the map [Peter Goodfellow (ICRF); Willard]. Most chromosome regions are being actively mapped both genetically and physically because a disease locus of interest exists in most intervals.

The Genome Data Base [Peter Pearson (Johns Hopkins University)] was accessible during the meeting so participants could input data and reference the database.

The third X Chromosome Workshop, to be organized by Daniela Toniolo (Consiglio Nazionale delle Richerche) and Michele D'Urso, will be held in Italy in 1992.


X Chromosome contact:

  • Kay Davies
    Molecular Genetics Group
    Institute of Molecular Medicine
    John Radcliffe Hospital
    Headington, Oxford OX3 9DU
    United Kingdom

Reference marker positions based on the X-chromosome committee report from HGM10.5 (Oxford) and modified to include information presented at the workshop. This information concerns physical ordering and map positions for the Xpter region together with the order of markers around the putative inactivation center and the fragile site (contributors acknowledged in text).


Reported by Kay Davies, Institute of Molecular Medicine and Ian Craig, University of Oxford

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Human Genome Project 1990–2003

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