Purpose: We have collected DNAs from 29 small families showing presumed autosomal recessive inheritance of either typical (17) or atypical RP (12). Our purpose is to determine the genetic lesion responsible for disease in each of these families by screening candidate genes first by haplotype analysis and then, if appropriate, by exon analysis and sequencing. To date the genes PDE6B, MYL5, PDE6C, CNCG, ROM1, RDS-peripherin, RHO and GNAG8 have been screened. Methods: Haplotype analysis was performed with simple sequence repeat markers (SSRs) that closely flank or are in or adjacent to seven of the candidate gene loci. In families where a candidate gene could not be ruled out from segregating with disease, the exons of the proband from the family were screened for point mutations in that gene by DGGE and SSCPE. The three exons of the GNAG8 gene were screened directly without haplotyping. Any DGGE or SSCPE variants were sequenced. Results: We previously reported two of these 29 families in which compound heterozygous mutations in the PDE6B gene were associated with RP(Genomics 30:1-7, 1995). Several of the remaining 27 families could not be ruled out from segregating with disease for each of the gene loci, and several sequence variants have been found for each of the gene loci except MYL5. However, so far, no sequence variants have been associated with disease. Sequence variants were also found in the GNAG8 gene, but none of these could be associated with disease either. Conclusions: Haplotype screening of small RP families followed by DGGE and SSCPE studies of exons from genes found to segregate with disease is an effective way to find recessive mutations in candidate genes (for example, PDE6B). This approach can also provide an estimate of the frequency of RP cases caused by defects in a particular gene (for example, 2/17 typical RP families with PDE6B mutations ≈ 12%).
|Original language||English (US)|
|Journal||Investigative Ophthalmology and Visual Science|
|State||Published - Feb 15 1996|
ASJC Scopus subject areas
- Sensory Systems
- Cellular and Molecular Neuroscience