The RS-KO mouse mimics structural features of human X-linked juvenile retinoschisis with dissection through, and disorganization of, multiple retinal layers. The Rs1h-KO functional deficit results in an electronegative ERG waveform that is characteristic of human retinoschisis disease and that implicates a synaptic transmission deficit in the absence of retinoschisin protein. Replacement therapy by supplementing normal Rs1h protein in the adult Rs1h-KO mouse restored the normal ERG configuration. This indicates that gene therapy is a viable strategy of therapeutic intervention even in the postdevelopmental adult stage of XLRS disease.

. Sieving. Primate retinal signaling pathways: suppressing ON-pathway activity in monkey with glutamate analogues mimics human CSNB1-NYX genetic night blindness.

To describe the clinical phenotype of juvenile X-linked retinoschisis in patients with different mutations in the XLRS1 gene. Methods: Thirty patients with 7 different XLRS1 mutations were examined. The genotype was determined by molecular genetics, which identified 6 known and 1 novel mutation (exon 5, 489 G→T). Ophthalmologic examination included full-field electroretinogram (ERG) recordings. Results: The fundus appearance showed marked variations between, as well as within, families with different XLRS1 mutations. The ERG demonstrated typical reduction of B-wave amplitude, with relative A-wave preservation, causing a reduced B-A ratio in all affected males. The implicit time of the 30-Hz flicker ERG was prolonged in all patients examined. In a large family with a deletion of exon 1 and the promoter region, 12 affected males showed a phenotype ranging from moderate to severe vision impairment and a broad range of ERG abnormality , suggesting that additional factors may contribute to the disease severity. Conclusions: Juvenile retinoschisis shows a wide variability in the phenotype between, as well as within, families with different genotypes. The ERG findings show reduced B-A ratios of dark-adapted recordings and prolonged implicit times of 30-Hz flicker response, which provide a useful clinical marker to confirm the clinical diagnosis. Clinical Relevance: This study describes the wide variability in the phenotype in patients with juvenile retinoschisis and different mutations in the XLRS1 gene. The study emphasizes the importance of complementing the ophthalmologic examination with full-field ERG and molecular genetics in boys with visual failure of unknown etiology to determine the diagnosis early in the course of the disease.

No abstract

Juvenile retinoschisis is an X-linked recessive disease caused by mutations in the XLRS1 gene. We screened 31 new unrelated patients and families for XLRS1 mutations in addition to previously reported mutations for 60 of our families (Retinoschisis Consortium, Hum Mol Genet 1998;7:1185-1192). Twenty-three different mutations including 12 novel ones were identified in 28 patients. Mutations identified in this study include 19 missense mutations, two nonsense mutations, one intragenic deletion, four microdeletions, one insertion, and one intronic sequence substitution that is likely to result in a splice site defect. Two novel mutations, c.38T®C (L13P) and c.667T®C (C223R), respectively, present the first genetic evidence for the functional significance of the putative leader peptide sequence and for the functional significance at the carboxyl terminal of the XLRS1 protein beyond the discoidin domain. Mutations in 25 of the families were localized to exons 4-6, emphasizing the critical functional significance of the discoidin domain of the XLRS1 protein. Hum Mutat 14:423-427, 1999.