CONSTRUCTION OF A YAC CONTIG AND AN STS MAP SPANNING 3.6 MEGABASE PAIRS IN XP22.1

We have constructed a 3.6 Mb sequence tagged sites (STS)-based yeast a rtificial chromosome (YAC) contig, consisting of 58 individual YAC clo nes, spanning the region PDHA1 and DXS451 on Xp22.1. In addition to es tablishing the order of PDHA1, ISPK-1, DXS2504, DXS1528 and the 13 kno wn polymorphic loci as Xpter - PDHA1 DXS443 - DXS3424 - ISPK-1 - DXS12 29 - DXS2504 - DXS1528 - DXS365 - DXS7101 - DXS1683 - DXS1052 - DXS274 - DXS92 - DXS1226 - DXS41 - DXS989 DXS451 - Xcen, we have also develo ped 35 novel STSs from YAC end clones. These results provide a high de nsity of STS markers (approximately 1 per 70 kb). Furthermore, a detai led long-range restriction map of the contig has been constructed with rare-cutter enzymes and this has refined and verified the physical di stances between markers inferred from YAC sizes and their STS content. The integration of the physical mapping data with previous genetic ma pping data and the use of STSs and non-chimeric YAC clones reported he re should facilitate the construction of a transcript map of this regi on and the positional cloning of disease genes in this portion of Xp22 .1.