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V. Vaclavik, S. H. Tsang, A. C. Bird, A. R. Robson, A. R. Webster, G. E. Holder; Phenotypic and Genotypic Findings in Atypical Cases of X-Linked Retinoschisis (XLRS). Invest. Ophthalmol. Vis. Sci. 2007;48(13):3685.
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To describe atypical clinical manifestations of genetically confirmed XLRS and to compare retinal function in those patients with a cohort having a more typical fundus phenotype.
Seven patients, without the typical fundus features of XLRS, were referred for investigation of reduced visual acuity. All patients underwent ISCEV-standard full-field electroretinography (ERG) and pattern ERG (PERG). Patients also underwent optical coherence tomography (OCT) and fundus autofluorescence (AF) imaging. Molecular genetic analysis was used to confirm the diagnosis of XLRS. The genetic and ERG findings were compared with those from 9 patients having a typical XLRS phenotype.
Visual acuities ranged from 6/9 to hand movements. Retinal examination revealed fine, intraretinal white dots within the macula, sometimes associated with localized retinal pigment epithelium abnormalities (5 cases). One case had an isolated unilateral retinal fold and one an isolated, unilateral small parafoveal lesion. All patients had an electronegative dark adapted bright flash ERG, consistent with generalized inner retinal dysfunction. Pattern ERGs were undetectable or subnormal in all cases indicating macular dysfunction. The full-field ERG abnormality directed mutational screening and all patients had mutation in RS1, including one case with a novel Leu69Pro mutation in exon 4. Fundus AF revealed a parafoveal ring of high density in three out of 6 eyes tested, one patient showed foci of high density corresponding to the white dots. OCT did not show foveal schisis in five out of eight eyes tested. There was no consistent difference in electrophysiology between this group and 9 patients with typical XLRS. Some RS1 mutations were common to both groups.
Fine white dots in the macula may be the first manifestation of X-linked retinoschisis, unaccompanied by the typical stellate lesions or foveal schisis. Electrophysiology is important to direct mutational screening. Abnormalities on AF imaging suggest RPE involvement in this disorder.
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