Homozygosity and physical mapping of the autosomal recessive retinitis pigmentosa locus (RP14) on chromosome 6p21.3

Retinitis pigmentosa (RP) is a heterogeneous genetic disorder with autosomal dominant, autosomal recessive, and X-linked forms. We previously mapped an additional arRP locus to chromosome 6p21 (RP14) in a single extended kinship from the Dominican Republic. Aided by a second linked RP pedigree from the same region of the Dominican Republic, we have refined the disease locus to a 2-cM region that is homozygous-by-descent in both pedigrees. A complete YAC, and a partial BAC, contig of the RP14 locus was constructed between the markers D6S1560 and D6S291, encompassing approximately 2.1 Mb. The contig contains 12 YACs and 31 BACs and is characterized by 45 markers including 8 microsatellite markers, 6 gene- derived sequences/ESTs obtained from the databases, and 28 new STSs and 4 new ESTs obtained by BLAST search using DNA sequence the ends of the BAC and YAC inserts. With a density of approximately 1 every 20 kilobases, this contig significantly enhances available maps of the region.