Abigail Teich Fahim

Background: The prevalence of foveal hypoplasia in different inherited retinal diseases (IRDs) has not been compared in a large patient cohort. We aimed to investigate the prevalence and visual significance of foveal hypoplasia in IRDs. Methods: Participants included patients with IRDs and control subjects. All patients had macular optical coherence tomography (OCT). Results: Among our 357 patients, 123 had rod-cone dystrophy (34.5%), 22 had cone/cone-rod dystrophy (6.2%), 30 had macular dystrophy (8.4%), and 182 (51%) were controls. Having a phenotype of rod-cone (OR = 12.9, p < 0.001) or cone/cone-rod dystrophy (OR = 10.2, p < 0.001) was associated with higher odds of having foveal hypoplasia. Males had higher odds of having foveal hypoplasia (OR = 2.4, p = 0.006). The prevalence of foveal hypoplasia in the retinitis pigmentosa GTPase regulator (RPGR) group (8/15 (53.3%)) was significantly higher than in matched controls (0/15, 0.0%) (p = 0.002). Atypical foveal hypoplasia had the highest LogMAR of 0.50 (±0.37), which was higher than grade one 0.16 (±0.17) (p = 0.038). Grade one LogMAR was not different from normal fovea 0.20 (±0.28) (p = 0.572). Conclusions: We report that rod-cone and cone/cone-rod IRDs are associated with foveal hypoplasia. Based on our findings, detection of foveal hypoplasia in a patient with reduced vision should prompt consideration of an IRD.

Introduction: X-linked inherited retinal dystrophies (IRDs) lead to progressive vision loss in affected males and include choroideremia (CHM), X-linked retinitis pigmentosa (XLRP), and X-linked cone-rod dystrophy (XLCORD). Female carriers may be asymptomatic or manifest disease ranging from mild to severe. Due to the variable manifestation of disease in females, some pedigrees can appear autosomal dominant. However, female carriers presenting as simplex probands are rare and X-linked disease may not be suspected in these cases without genetic testing. Case Presentations: Three affected simplex CHM carriers and six affected simplex XLRP or XLCORD carriers due to variants in RPGR (n = 5) or RP2 (n = 1) were included. Best corrected visual acuity, color fundus photos, fundus autofluorescence (FAF), optical coherence tomography, electroretinography, and Goldmann visual fields were collected. X-chromosome inactivation (XCI) ratios were determined for 4 cases. Age of onset ranged from infancy to 43 years, with nyctalopia as the most common presenting symptom. 4 out of 5 cases with RPGR variants presented with cone or cone-rod dystrophies, while the remaining cases presented with rod-cone dystrophy. XCI analysis revealed extreme skewing in 2 cases who both presented with severe disease. 4 out of 7 cases with FAF demonstrated autofluorescence patterns classic for carrier status. The remaining 3 cases had severe disease and corresponding FAF patterns consistent with their severity. Conclusion: The absence of family history does not preclude X-linked inheritance in females with retinal dystrophies. Multimodal imaging such as FAF and red-free photos should be included in the workup. As new therapeutic strategies are developed for CHM and RPGR-associated retinal degeneration, including gene therapy, it may become increasingly more important to diagnose symptomatic carriers, as it has been previously shown that earlier intervention is more effective in IRD populations.

Choroideremia is an X-linked chorioretinal dystrophy caused by mutations in CHM, encoding Rab escort protein 1 (REP-1), leading to under-prenylation of Rab GTPases (Rabs). Despite ubiquitous expression of CHM, the phenotype is limited to degeneration of the retina, retinal pigment epithelium (RPE), and choroid, with evidence for primary pathology in RPE cells. However, the spectrum of under-prenylated Rabs in RPE cells and how they contribute to RPE dysfunction remain unknown. A CRISPR/Cas-9-edited CHM^−/− iPSC-RPE model was generated with isogenic control cells. Unprenylated Rabs were biotinylated in vitro and identified by tandem mass tag (TMT) spectrometry. Rab12 was one of the least prenylated and has an established role in suppressing mTORC1 signaling and promoting autophagy. CHM^−/− iPSC-RPE cells demonstrated increased mTORC1 signaling and reduced autophagic flux, consistent with Rab12 dysfunction. Autophagic flux was rescued in CHM^−/− cells by transduction with gene replacement (ShH10-CMV-CHM) and was reduced in control cells by siRNA knockdown of Rab12. This study supports Rab12 under-prenylation as an important cause of RPE cell dysfunction in choroideremia and highlights increased mTORC1 and reduced autophagy as potential disease pathways for further investigation.

Acute exudative polymorphous vitelliform maculopathy (AEPVM) has recently been identified as a paraneoplastic manifestation of various cancers. Yet, the first reported cases of AEPVM in the literature were reported in seemingly healthy individuals. It is not clear whether those individuals harbored unidentified mutations or occult cancers, or truly represented a separate subset of AEPVM. Here, we report two cases of mutationnegative, autoantibody-positive non-paraneoplastic AEPVM. We present multimodal ocular imaging to demonstrate the presentation of this subset of AEPVM. [Ophthalmic Surg Lasers Imaging Retina 2024;55:51-54.]

The retinal pigment epithelium (RPE) is a polarized monolayer that secretes growth factors and cytokines towards the retina apically and the choroid basolaterally. Numerous RPE secreted proteins have been linked to the pathogenesis of age-related macular degeneration (AMD). The purpose of this study was to determine the differential apical and basolateral secretome of RPE cells, and the effects of oxidative stress on directional secretion of proteins linked to AMD and angiogenesis. Tandem mass tag spectrometry was used to profile proteins in human iPSC-RPE apical and basolateral conditioned media. Changes in secretion after oxidative stress induced by H₂O₂ or tert-butyl hydroperoxide (tBH) were investigated by ELISA and western analysis. Out of 926 differentially secreted proteins, 890 (96%) were more apical. Oxidative stress altered the secretion of multiple factors implicated in AMD and neovascularization and promoted a pro-angiogenic microenvironment by increasing the secretion of pro-angiogenic molecules (VEGF, PTN, and CRYAB) and decreasing the secretion of anti-angiogenic molecules (PEDF and CFH). Apical secretion was impacted more than basolateral for PEDF, CRYAB and CFH, while basolateral secretion was impacted more for VEGF, which may have implications for choroidal neovascularization. This study lays a foundation for investigations of dysfunctional RPE polarized protein secretion in AMD and other chorioretinal degenerative disorders.