A novel mutation in the RS1 gene in a Chinese family with X-linked congenital retinoschisis.

Abstract

The purpose of the present study was to assess the clinical characteristics of X-linked retinoschisis (XLRS) in a Chinese family over a 7-year period with the aim of identifying possible genetic mutations associated with this disease. A total of 2 male siblings from a family with XLRS were followed up for 7 years and the best-corrected visual acuity and data obtained using slit-lamp microscopy, indirect ophthalmoscopy, fundus photography, spectral domain-optical coherence tomography (OCT), fundus autofluorescence and fundus fluorescence (FFA) and multifocal electroretinograms (ERG) were examined. The coding regions of the retinoschisin 1 (RS1) gene were amplified by PCR and sequenced directly. The proband exhibited blurred vision at 12 years old and was indicated to exhibit a typical phenotype of XLRS at 30 years old. The elder brother exhibited blurred vision at 11 years old and was diagnosed with XLRS at 33 years old. There was no change in the best-corrected visual acuities in the two patients over the 7 years. The OCT results suggested that there were intraretinal cysts and macular atrophy in the eyes of the older sibling, whilst a ‘spoke-wheel’ pattern was present in the macula of the younger sibling. In addition, OCT examination revealed foveal schisis. FFA analysis indicated a hyperfluorescent signal in the central macula. Multifocal ERG recordings indicated that responses were markedly reduced in the central and outer rings bilaterally. The central retinal thickness of the younger sibling increased but the central retinal thickness of the older sibling was not changed during the 7 years. Sequencing analysis revealed that the mutation was c.366G>A (p.Trp122*) in exon 5 of Xp22.1. Gene mutation analysis indicated that the affected male siblings harbored a Trp122* (c.366G>A) mutation, while the patients' mother was demonstrated to be a heterozygous carrier of the pathogenic mutation. To conclude, the present study discovered a novel XLRS mutation in a Chinese family, where the Trp122* mutation caused a significant change in the function of the RS1 protein. Over the 7 years of observation, although the vision was not significantly impaired in the two patients examined, the central retinal thickness of the younger sibling increased but the central retinal thickness of the older sibling was not altered.