Elsevier

Genomics

Volume 1, Issue 4, December 1987, Pages 297-306
Genomics

Physical mapping studies on the human X chromosome in the region Xq27-Xqter

https://doi.org/10.1016/0888-7543(87)90028-0Get rights and content

Abstract

We have characterized three terminal deletions of the long arm of the X chromosome. Southern analysis using Xq27q28 probes suggests that two of the deletions have breakpoints near the fragile site at Xq27.3. Flow karyotype analysis provides an estimate of 12 × 106 bp for the size of the deleted region. We have not detected the deletion breakpoints by pulsed-field gel electrophoresis (PFGE) using the closest DNA probes, proximal to the fragile site. The physical distance between the breakpoints and the probes may therefore be several hundred kilobases. The use of the deletion patients has allowed a preliminary physical map of Xq2728 to be constructed. Our data suggest that the closest probes to the fragile site on the proximal side are 4D-8 (DXS98), cX55.7 (DXS105), and cX33.2 (DXS152). PFGE studies provide evidence for the physical linkage of 4D-8, cX55.7, and cX33.2. We have also found evidence for the physical linkage of F8C, G6PD, and 767 (DXS115), distal to the fragile site.

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    Present address: Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada.

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