CHARACTERIZING THE NATURAL HISTORY OF FOVEAL-SPARING ATROPHIC LATE-ONSET RETINAL DEGENERATION

Treatment Strategy With Gene Editing for Late-Onset Retinal Degeneration Caused by a Founder Variant in C1QTNF5

Purpose

Genome editing is an emerging group of technologies with the potential to ameliorate dominant, monogenic human diseases such as late-onset retinal degeneration (L-ORD). The goal of this study was to identify disease stages and retinal locations optimal for evaluating the efficacy of a future genome editing trial.

Methods

Twenty five L-ORD patients (age range, 33-77 years; median age, 59 years) harboring the founder variant S163R in C1QTNF5 were enrolled from three centers in the United Kingdom and United States. Patients were examined with widefield optical coherence tomography (OCT) and chromatic perimetry under dark-adapted and light-adapted conditions to derive phenomaps of retinal disease. Results were analyzed with a model of a shared natural history of a single delayed exponential across all subjects and all retinal locations.

Results

Critical age for the initiation of photoreceptor loss ranged from 48 years at the temporal paramacular retina to 74 years at the inferior midperipheral retina. Subretinal deposits (sRET-Ds) became more prevalent as critical age was approached. Subretinal pigment epithelial deposits (sRPE-Ds) were detectable in the youngest patients showing no other structural or functional abnormalities at the retina. The sRPE-D thickness continuously increased, reaching 25 µm in the extrafoveal retina and 19 µm in the fovea at critical age. Loss of light sensitivity preceded shortening of outer segments and loss of photoreceptors by more than a decade.

Conclusions

Retinal regions providing an ideal treatment window exist across all severity stages of L-ORD.

Longitudinal Changes of Retinal Structure in Molecularly Confirmed C1QTNF5 Patients With Late-Onset Retinal Degeneration

Purpose

The purpose of this study was to present our findings on the natural history of late-onset retinal degeneration (LORD) in patients with molecularly confirmed C1QTNF5 heterozygous pathogenic variants and assess suitability of retinal structure parameters for disease monitoring.

Methods

Sixteen patients with C1QTNF5-LORD were retrospectively identified from Moorfields Eye Hospital, UK. Fundus autofluorescence (FAF), optical coherence tomography (OCT) scans, and best-corrected visual acuity (BCVA) were collected. Area of atrophy (AA) was manually drawn in FAF images. Ellipsoid zone (EZ) width and foveal retinal thickness of the whole retina and outer retina were extracted from OCT scans. Age-related changes were tested with linear-mixed models.

Results

Patients had median age of 62.3 years (interquartile range [IQR] = 58.8-65.4 years) at baseline, and median follow-up of 5.1 years (IQR = 2.6-7.6 years). AA, EZ width, and retinal thickness parameters remained unchanged until age 50 years, but showed significant change with age thereafter (all P < 0.0001). AA and EZ width progressed rapidly (dynamic range normalized rates = 4.3-4.5%/year) from age 53.9 and 50.8 years (estimated inflection points), respectively. Retinal thickness parameters showed slower progression rates (range = 1.6-2.5%/year) from age 60 to 62.3. BCVA (median = 0.3 LogMAR, IQR = 0.0-1.0 at baseline) showed a rapid decline (3.3%) from age 70 years. Findings from patients with earlier disease showed FAF atrophy manifests in the temporal retina initially, and then progresses nasally.

Conclusions

Patients with LORD remained asymptomatic until age 50 years, before suffering rapid outer retinal degeneration. EZ width and AA showed rapid progression and high interocular correlation, representing promising outcome metrics. Clinical measures also capturing the temporal retina may be preferable, enabling earlier detection and better disease monitoring.

Translational Relevance

Area of atrophy in FAF images and OCT-measured EZ width represent promising outcome metrics for disease monitoring in patients with C1QTNF5-LORD.

MICROPERIMETRY IN FOVEAL-SPARING ATROPHIC LATE-ONSET RETINAL DEGENERATION

PURPOSE

To understand the baseline and longitudinal microperimetry characteristics in foveal-sparing atrophic late-onset retinal degeneration.

METHOD

Prospective, cross-sectional, longitudinal study in which patients from the retina clinics of two academic teaching hospitals were included. Mesopic microperimetry was performed using a Nidek MP-1 micro-perimeter. Mean total, foveal, inner ring, and outer ring sensitivities were analyzed.

RESULTS

A total of 20 eyes from 10 patients had baseline data. The subset of 10 eyes from five patients had follow-up data. The mean baseline macular sensitivity was 10.02 dB (± 5.26) with findings showing symmetry between both eyes. In the follow-up cohort, there was a significant loss of outer ring (0.83 dB per year; P = 0.0001), inner ring (0.67 dB per year; P = 0.034), and foveal sensitivity (0.92 dB loss per year; P = 0.015), whereas the mean sensitivity decreased significantly (0.66 dB per year; P = 0.0008) at 4-year follow-up. The drop in mean sensitivity was associated with significant increases in the number of deep scotoma points (6.20, P = 0.037) and a decrease in the number of normal points (-6.30, P = 0.022).

CONCLUSION

Microperimetry is a useful tool for macular function follow-up to measure disease progression in late-onset retinal degeneration.

Anterior segment phenotypic changes in late-onset retinal degeneration with Ser163Arg mutation in CTRP5/C1QTNF5

PURPOSE

Late-onset retinal degeneration (L-ORD) is a rare retinal dystrophy with anterior segment (AS) abnormalities, including long anterior zonules (LAZ) and iris atrophy. This investigation evaluates AS changes in a L-ORD cohort.

METHODS

Prospective, longitudinal study including L-ORD individuals (Ser163Arg) with ocular exam and standard slit-lamp photographs between 2011 and 2022. AS images were merged and assessed for LAZ number and zonule-free zone (ZFZ) radius. Further clinical findings such as iris atrophy patterns were reported descriptively.

RESULTS

Twelve eyes of 6 patients (4 males, median age = 60.5 years) were included, showing a median of 160 (11-372) LAZs, mainly localized superiorly (39%) and inferiorly (24%). There was a high inter-ocular correlation (rs = 0.94, p < 0.01), no difference in LAZ count between eyes (p = 0.82), and an inverse relationship between LAZ and age (r =  - 0.82; p < 0.05). The ZFZ had median 2.1 mm (1.3-5.4), with no inter-ocular difference (p = 0.31). Iris transillumination defects occurred in 11/12 eyes, with 4 major patterns identified: pupillary ruff rarefaction (10/12), patchy atrophy (6/12), notched defects (6/12), and radial streaks (2/12). In a short-term follow-up of 5.9 years, 4 eyes showed a reduction in LAZ count to median 139.5 (67-169) (p = 0.50) and a concomitant increase in ZFZ measurement to median 2.2 (1.7-2.6) (p = 0.17).

CONCLUSION

This study confirms symmetric LAZs count and ZFZ in L-ORD, with ZFZ measurements smaller than in previous cohorts. A reduction in LAZs count and an increase in ZFZ with age were suggested longitudinally, yet findings need further evaluation as follow-up was limited to two cases.

Late-Onset Retinal Degeneration: Clinical Perspectives

Late-onset retinal degeneration (L-ORD) is a type of retinal dystrophy marked by nyctalopia and subretinal pigment epithelium deposits, which eventually promote retinal atrophy with final visual compromise. L-ORD may also present with changes in the anterior segment, notably long anterior zonules and iris atrophy, distinguishing it from other inherited eye conditions. Although it can clinically simulate age-related macular degeneration, L-ORD has a different course of progression and prognosis, requiring adequate diagnosis for patient counseling. This review summarizes the main clinical, genetic, pathophysiological, diagnostic, and therapeutic aspects of L-ORD to help ophthalmologists identify and manage this rare ocular disease.

Autosomal Dominant Gyrate Atrophy-Like Choroidal Dystrophy Revisited: 45 Years Follow-Up and Association with a Novel C1QTNF5 Missense Variant

We present a long-term follow-up in autosomal dominant gyrate atrophy-like choroidal dystrophy (adGALCD) and propose a possible genotype/phenotype correlation. Ophthalmic examination of six patients from two families revealed confluent areas of choroidal atrophy resembling gyrate atrophy, starting in the second decade of life. Progression continued centrally, reaching the fovea at about 60 years of age. Subretinal deposits, retinal pigmentation or choroidal neovascularization as seen in late-onset retinal degeneration (LORD) were not observed. Whole genome sequencing revealed a novel missense variant in the C1QTNF5 gene (p.(Q180E)) which was found in heterozygous state in all affected subjects. Haplotype analysis showed that this variant found in both families is identical by descent. Three-dimensional modeling of the possible supramolecular assemblies of C1QTNF5 revealed that the p.(Q180E) variant led to the destabilization of protein tertiary and quaternary structures, affecting both the stability of the single protomer and the entire globular head, thus exerting detrimental effects on the formation of C1QTNF5 trimeric globular domains and their interaction. In conclusion, we propose that the p.(Q180E) variant causes a specific phenotype, adGALCD, that differs in multiple clinical aspects from LORD. Disruption of optimal cell-adhesion mechanisms is expected when analyzing the effects of the point mutation at the protein level.