Genotype–Phenotype Correlations in 83 Korean X-linked Retinoschisis Patients: Impact of Retinoschisin 1 Secretion Profiles on Clinical Phenotypes

Abstract

To assess the correlation between genotype and phenotype severity in X-linked juvenile retinoschisis (XLRS) by examining clinical and genetic features of a cohort of Korean XLRS patients. Retrospective, observational study. Data from 83 consecutive male patients with molecularly confirmed XLRS were collected retrospectively. Clinical evaluation included best-corrected visual acuity (BCVA), fundus photography, spectral-domain optical coherence tomography (SD-OCT), and full-field electroretinography (ERG). The phenotypic characteristics of a cohort of pediatric Korean XLRS patients, based on mutation types (truncating versus missense) and secretory profile (secretion versus non-secretion), were assessed. One hundred sixty-six eyes of 83 patients were included. The mean age at diagnosis was 6.1 ± 8.8 years (range, 0.5-20.7 years), with a mean follow-up time of 9.2 ± 7.0 years (range, 0.6-24.3 years). The BCVA at first and last examination ranged from light perception to 0.1 logarithm of the minimum angle of resolution (mean ± SD, 0.75 ± 0.59 and 0.82 ± 0.65, respectively). There were no significant differences in the first and last BCVA measurements between the truncating (0.71 ± 0.51 and 0.75 ± 0.44) and missense (0.77 ± 0.59 and 0.84 ± 0.66) variants (P = 0.678 and 0.551, respectively). Additionally, there were no differences in clinical parameters from fundus photography, SD-OCT, and full-field ERG. However, the BCVA at the first and last measurement were better for patients in the secretion group (0.51 ± 0.24 and 0.61 ± 0.30) compared to patients in the non-secretion group (0.65 ± 0.71 and 0.87 ± 0.81). The last BCVA showed a statistically significant difference between the two groups (P = 0.021). In OCT findings, the frequency of ellipsoid zone disruption was higher in patients with non-secretion variants than those with secretion variants (P = 0.030), with no significant differences in other parameters. The secretion profile of RS1 could influence the severity of XLRS phenotypes. Patients with RS1-secreted mutants, particularly with intact octamerization, exhibit more homogeneous phenotypes and better visual acuity than the RS1-non-secreted group. This data provides insights for studying genotype and phenotype correlations in both clinical and research fields.