Generation of sequence-tagged sites from Xp22.3 by isolating common Alu-PCR products of radiation hybrids retaining overlapping human X chromosome fragments.

Several human diseases have been mapped to Xp22.3 on the distal short arm of the human X chromosome, and many genes in this area have been found to be expressed from the inactive X chromosome. To facilitate physical mapping and characterization of this interesting region, we have constructed a battery of radiation hybrids containing human X chromosomal fragments, and isolated two hybrid clones A with overlapping fragments of Xp22.3. Alu-PCR on these hybrids and identification of sequences common to both hybrids allowed the isolation of six sequences-tagged sites (STSs) from Xp22.3. Five of the STSs were mapped+ to individual YACs comprising a recently constructed contig of this region. These novel STSs are useful markers for further physical characterization of this part of the genome.