Abstract
Abstract: :
Purpose: Mice with a nullizygosity for the gene encoding the Na+-dependent taurine transporter Slc6a6 display a pattern of retinal degeneration resembling forms of human retinitis pigmentosa or an allied disease. To search for a human disease that might correspond to that found in the Slc6a6(-/-) mice, we are screening the human homologue SLC6A6 for possible mutations in patients with autosomal dominant and autosomal recessive retinitis pigmentosa and Leber congenital amaurosis. Methods: Leukocyte DNA samples from 95 unrelated patients with autosomal dominant retinitis pigmentosa (ADRP), 125 unrelated patients with autosomal recessive retinitis pigmentosa (ARRP), and 63 unrelated patients with Leber congenital amaurosis (LCA) are being evaluated for mutations in all coding exons and the flanking intron sequences by direct genomic sequencing. Results: To date, 1 heterozygous missense change, Val128Ile (GTT>ATT), was found in 4 ADRP patients. This change is unlikely to be pathogenic since it was found not to cosegregate with disease in one patient's family. Two isocoding changes were also found. Leu10Leu (CTG>TTG) was found heterozygously in 1 ARRP patient, and Gly56Gly (GCC>GGT) was found heterozygously in 2 ADRP patients and 1 ARRP patient. These isocoding changes were evaluated with splice-site prediction software and were predicted not to alter RNA splicing. Approximately 16% of the gene remains to be evaluated in our set of patients. Conclusions: We have yet to find any variants within the SLC6A6 gene that are convincing causes of dominant or recessive forms of retinitis pigmentosa or Leber congenital amaurosis. The screening of patients with other forms of retinal degeneration is ongoing.
Keywords: candidate gene analysis • retinitis • genetics