CHARACTERIZATION OF A YAC CONTIG SPANNING THE PSEUDOAUTOSOMAL REGION

Due to its unique biology of partial sex linkage and high recombinatio n rates, the pseudoautosomal region (PAR1) on both X and Y chromosomes has attracted considerable interest. In addition, an extremely high l evel of YAC instability has been observed in this region. We have deri ved 82 YAC clones from six different YAC libraries mapping to this 2.6 -Mb region. Of these a subset of 22 YACs was analyzed in detail. YAC c ontigs were assembled using 67 pseudo autosomal probes, of which 64 we re unambiguously ordered. All markers are well distributed over the en tire region, including the middle part of the region, which has previo usly been found difficult to contig. Two gaps of less than 50 kb withi n the genomic locus of CSF2RA and around XE7 remain, which could not b e covered with YACs, cosmids, or phages. This YAC contig anchored on t he physical map of PAR1 represents one of the best characterized large regions of the human genome with a map completion greater than 90% at 100-kb resolution and has permitted the accurate localization of all known genes within this region. (C) 1995 Academic Press, Inc.