X‐linked juvenile retinoschisis: different mutations – same phenotype

Purpose To describe the phenotype‐genotype correlation of three X‐linked retinoschisis (XLRS) cases in juveniles with different novel mutations from Lithuanian population. Methods Based on clinical symptoms and family history, a preliminary diagnosis of XLRS was established in three adolescent male patients. Comprehensive ophthalmological examinations, including best‐corrected visual acuity (BCVA), slit‐lamp, fundus examination, spectral domain optical coherent tomography (SD‐OCT) and full‐field electroretinography, were performed. RS1 (NM_000330.3) gene coding exons Sanger sequencing was performed. Results At the time of ophtalmic and genetic counselling the patients were 9, 12 and 17 years old. The patients demonstrated macular retinoschisis and typical cyst‐like cavities on SD‐OCT images with logMAR BCVA ranging from 0.5 to 0.2. The mean central foveal thickness was 569.7 μm. Two of the three patients presented with peripheral retinoschisis. Flash‐ERG demonstrated a reduced b/a ratio (T (p.R200L) mutation was detected in one case, in silico analysis showing to be pathogenic. HGMD involves three other different mutations at the same position supporting the pathogenicity of the identified variant. c.(92_97)insC (p.W33 fs) mutation was identified for another proband, in silico analysis indicating the variant is possibly damaging. The third case was identified with a pathogenic mutation c.422C>G (p.R141H), HGMD CM981753. Conclusions These are the first cases of XLRS in the Lithuanian population confirmed by molecular genotyping. Although clinical expression of XLRS is highly variable presented patients had a different genotype but similar phenotypic traits. Functional analysis would be of benefit to characterise the identified variants on the effect of retinoschisin expression.