Genetic and physical mapping of a novel region close to the fragile X site on the human X chromosome

M. N. Patterson, M. V. Bell, J. Bloomfield, T. Flint, H. Dorkins, S. N. Thibodeau, D. Schaid, G. Bren, C. E. Schwartz, b. Wieringa, H. H. Ropers, D. F. Callen, G. Sutherland, U. Froster-Iskenius, H. Vissing, K. E. Davies

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


We report the isolation and characterization of a novel DNA marker (1A1) in Xqter in the region of the fragile X. Genetic studies in families segregating for the fragile X syndrome suggest that 1A1 lies between the disease mutation and the distal locus, DXS52. Studies in normal and fragile X families show that 1A1 is tightly linked to DXS52 (Zmax = 17.20; θmax = 0.03) and F8 (Zmax = 7.01; θmax = 0.08). Multipoint mapping of families supports the order Xcen-DXS105-FRAXA-1A1-DXS52-(F8, DXS115)-Xqter. Pulsed-field gel electrophoresis (PFGE) studies demonstrate that 1A1 defines a new region of at least 2 Mb of DNA not physically linked to DXS52 or F8, thus extending the physical map of Xq27-qter to over 4 Mb. Complex partial digestion PFGE patterns, probably due to differing degrees of methylation, are observed with 1A1 in unrelated normal and fragile-X-positive individuals, whereas other distal markers give uniform digestion profiles. Physical data suggest that 1A1 lies in a region less CpG rich than other distal markers in Xq27-qter.

Original languageEnglish (US)
Pages (from-to)570-578
Number of pages9
Issue number4
StatePublished - May 1989

ASJC Scopus subject areas

  • Genetics


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