YAC STS MAP ACROSS 12 MB OF XQ27 AT 25-KB RESOLUTION, MERGING XQ26-QTER/

A 12-Mb YAC contig has been assembled spanning the Xq27 cytogenetic ba nd with 203 YACs, 121 STSs, and >300 hybridization probes to a resolut ion of 25 lib. At its centromeric end, the contig is merged with a 9-M b contig covering Xq26.1-q26.3 at a point 1 Mb telomeric to the factor IX gene; at its telomeric end, it is merged to 7.5 Mb of contigs fi o m the IDS gene to the Xq28 telomere, Thus, the distal 29 Mb of the Xq arm is available cloned in long-range contiguity. The physical map has been integrated with current genetic data by the localization of 18 m arkers that detect polymorphism. Apparent recombination levels reach > 4.5 cM/Mb near the centromeric border of Xq27. The ratio of cM/Mb corr espondingly delimits the location of several disease genes - including , for trample, X-linked hypoparathyroidism in 3 Mb (6 cM) telomeric to Factor IX. (C) 1996 Academic Press, Inc.