X-linked retinoschisis: mutation spectrum and genotype-phenotype relationship in an Italian pediatric cohort

A retrospective longitudinal study of 52 Finnish patients with X-linked retinoschisis

PURPOSE

To describe clinical characteristics in Finnish patients with X-linked retinoschisis (XLRS) longitudinally with emphasis on retinal morphology and genotype-phenotype correlations.

METHODS

A retrospective cohort study reviewed medical records from patients with genetically confirmed XLRS from the Department of Ophthalmology, Helsinki University Hospital. Best-corrected visual acuity (BCVA), refraction, colour fundus photography, spectral-domain optical coherence tomography and genetic information were collected.

RESULTS

Fifty-two males were diagnosed at the median age of 7 years (range 1-57) and followed for a median of 8 years (range, 1-49). Baseline findings included macular retinoschisis in 92 (89%), macular atrophy in 25 (24%) and peripheral retinoschisis in 22 (21%) eyes. Vitreous haemorrhage occurred in 10 (10%) eyes, more frequently with peripheral schisis (p < 0.001). Nearly half of the patients, 22 (42%) were classified as visually impaired according to WHO. Median central retinal thickness was similar between initial (355 μm) and latest visits (360 μm) (p = 0.781). Low BCVA was associated with macular atrophy (p < 0.001), ellipsoid zone disruption (p = 0.007) and peripheral retinoschisis (p = 0.006). The three Finnish founder mutations c.214G >A, c.221G >T, and c.325G >C in exon 4 of retinoschisin 1 (RS1) were identified in 40 patients (77%). No associations were found between the genotypes and phenotypes.

CONCLUSION

Three-fourths of the patients carried the Finnish founder mutations in RS1, but we did not detect any genotype-phenotype association. Macular atrophy was associated with the poorest visual acuity. Ocular compilations were associated with peripheral retinoschisis, suggesting that these patients should be followed more frequently.

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

PURPOSE

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.

DESIGN

Retrospective, observational study.

PARTICIPANTS

Data from 83 consecutive male patients with molecularly confirmed XLRS were collected retrospectively.

METHODS

Clinical evaluation included best-corrected visual acuity (BCVA), fundus photography, spectral domain OCT (SD-OCT), and full-field electroretinography (ERG).

MAIN OUTCOME MEASURES

The phenotypic characteristics of a cohort of pediatric Korean patients with XLRS, based on mutation types (truncating vs. missense) and secretory profile (secretion vs. nonsecretion), were assessed.

RESULTS

A total of 166 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 ± standard deviation, 0.75 ± 0.59 and 0.82 ± 0.65, respectively). No significant differences were observed 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). Clinical parameters from fundus photography, SD-OCT, and ERG showed no differences. However, BCVA was better for the secretion group (0.51 ± 0.24 and 0.61 ± 0.30) than for the nonsecretion group (0.65 ± 0.71 and 0.87 ± 0.81), with a significant difference in the last BCVA (P = 0.021). OCT revealed a higher frequency of ellipsoid zone disruption in the nonsecretion group (P = 0.030), with no significant differences in other parameters.

CONCLUSIONS

The secretion profile of Retinoschisin 1 (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-nonsecreted group. This data provide insights for studying genotype and phenotype correlations in both clinical and research fields.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any materials discussed in this article.

Efficacy of Carbonic Anhydrase Inhibitors on Cystoid Fluid Collections and Visual Acuity in Patients with X-Linked Retinoschisis

PURPOSE

To date, there is no standard treatment regimen for carbonic anhydrase inhibitors (CAIs) in X-linked retinoschisis (XLRS) patients. This retrospective study aims to evaluate the efficacy of CAIs on visual acuity and cystoid fluid collections (CFC) in XRLS patients in Dutch and Belgian tertiary referral centers.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Forty-two patients with XLRS.

METHODS

In total, 42 patients were enrolled. To be included, patients had to have previous treatment with an oral CAI (acetazolamide), a topical CAI (brinzolamide/dorzolamide), or a combination of an oral and a topical CAI for at least 4 consecutive weeks. We evaluated the effect of the CAI on best-corrected visual acuity (BCVA) and central foveal thickness (CFT) on OCT.

MAIN OUTCOME MEASURES

Central foveal thickness and BCVA.

RESULTS

The median age at the baseline visit of the patients in this cohort study was 14.7 (range, 43.6) years, with a median (interquartile range [IQR]) follow-up period of 4.0 (2.2-5.2) years. During the follow-up period, 25 patients were treated once with an oral CAI (60%), 24 patients were treated once with a topical CAI (57%), and 11 patients were treated once with a combination of both topical and oral CAI (26%). We observed a significant reduction of CFT for oral CAI by 14.37 μm per 100 mg per day (P < 0.001; 95% confidence interval [CI], -19.62 to -9.10 μm) and for topical CAI by 7.52 μm per drop per day (P = 0.017; 95% CI, -13.67 to -1.32 μm). The visual acuity changed significantly while on treatment with oral CAI by -0.0059 logMAR per 100 mg (P = 0.008; 95% CI, -0.010 to -0.0013 logMAR). Seven patients (17%) had side effects leading to treatment discontinuation.

CONCLUSIONS

Our data indicate that treatment with (oral) CAI may be beneficial for short-term management of CFC in patients with XLRS. Despite a significant reduction in CFT, the change in visual acuity was modest and not of clinical significance. Nonetheless, the anatomic improvement of the central retina in these patients may be of value to create an optimal retinal condition for future potential treatment options such as gene therapy.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any materials discussed in this article.