Abstract
Under syndrome type Ib, a recessive disorder characterized by deafness, retinitis pigmentosa, and vestibular dysfunction has been mapped to chromosome 11q13. A 3 Mb YAC contig has been constructed covering the critical region of Usher Ib and spanning over eight loci: D11S1321, D11S527, D11S533, OMP, D11S906, D11S911, D11S937, and D11S918. This contig was constructed by PCR screening using the above described DNA markers of the CEPH mega YAC library. Additional YACs were identified by data presented in the Genethon physical map. A long-range restriction map has been constructed from both YAC and genomic DNA using STS markers as probes. Cosmid libraries from a subset of YACs have been screened for the location of CpG islands. In addition, potential transcribed regions have been identified by 3{prime} exon trapping of cosmid pools and placed on the YAC physical map.