A 4.3 Mb YAC Contig in Human Xp11.2: Long-Range Restriction Mapping and Identification of CpG Islands.

The Xp11.2 region o the human X chromosome contains genes involved in a number of inherited diseased, with at least one locus that escapes X chromosome inactivation, as well as abnormal methylation polymorphism. We isolated a series of yeast artificial chromosome (YAC) clones by hybridization screening with DNA probes localized within this region and assembled them into a 4.3 Mb contig spanning from Xp11.21 to Xp11.23 by a combination of Alu-PCR fingerprinting, STS-PCR and DNA probe cross hybridization. On the basis of these overlapping YAC clones we have constructed the long-range restriction map of this interval and placed exactly some DNA markers. Four CpG-dense regions between ARAF1 and OATL2 were identified based on the long-range restriction mapping, which indicated the distribution of genes within this interval. It should assist in the future nucleic acid sequence analysis and novel gene identification in this region.