AN 8TH LOCUS FOR AUTOSOMAL-DOMINANT RETINITIS-PIGMENTOSA IS LINKED TOCHROMOSOME-17Q

Retinitis pigmentosa is one of the most common causes of severe visual handicap in middle to late life, Prior to this report, seven loci had previously been mapped for the autosomal dominant form of this disord er (adRP), We now report the identification of a novel adRP locus on c hromosome 17q. To map the new locus, we performed linkage analysis wit h microsatellite markers in a large South African kindred. After exclu sion of 13 RP candidate gene loci (including rhodopsin and peripherin- RDS), we obtained significant positive lod scores at zero recombinatio n fraction (theta = 0) for D17S808 (Z = 4.63) and D17S807 (Z = 5.69), Multipoint analysis gave a maximum lod score of 8.28 between these two markers. From haplotype analysis, the disease locus lies in the inter val between markers D17S809 and D17S942. Three candidate genes for ret inal dystrophies map to this chromosomal region and these genes are cu rrently being investigated for possible involvement with adRP in this family.