Correction of Monogenic and Common Retinal Disorders with Gene Therapy

The past decade has seen major advances in gene-based therapies, many of which show promise for translation to human disease. At the forefront of research in this field is ocular disease, as the eye lends itself to gene-based interventions due to its accessibility, relatively immune-privileged status, and ability to be non-invasively monitored. A landmark study in 2001 demonstrating successful gene therapy in a large-animal model for Leber congenital amaurosis set the stage for translation of these strategies from the bench to the bedside. Multiple clinical trials have since initiated for various retinal diseases, and further improvements in gene therapy techniques have engendered optimism for alleviating inherited blinding disorders. This article provides an overview of gene-based strategies for retinal disease, current clinical trials that engage these strategies, and the latest techniques in genome engineering, which could serve as the next frontline of therapeutic interventions

Hyperautofluorescent Dots are Characteristic in Ceramide Kinase Like-associated Retinal Degeneration.

There is a lack of studies which seek to discern disease expression in patients with mutations that alter retinal ceramide metabolism, specifically in the ceramide kinase like (CERKL) gene. This cross-sectional case series reports a novel phenotypic manifestation of CERKL-associated retinopathy. Four unrelated patients with homozygous CERKL mutations underwent a complete ocular exam, spectral-domain optical coherence tomography, short-wavelength fundus autofluorescence (SW-AF), quantitative autofluorescence (qAF), and full-field electroretinogram (ffERG). Decreased visual acuity and early-onset maculopathy were present in all patients. All four patients had extensive hyperautofluorescent foci surrounding an area of central atrophy on SW-AF imaging, which has not been previously characterized. An abnormal spatial distribution of qAF signal was seen in one patient, and abnormally elevated qA

Patterns and Intensities of Near-Infrared and Short-Wavelength Fundus Autofluorescence in Choroideremia Probands and Carriers

PURPOSE. To ascertain cellular constituents within islands of preserved retina in choroideremia (CHM) by multimodal imaging. METHODS. CHM probands (16) and female carriers (9) of CHM were studied. Near-infrared autofluorescence (NIR-AF; 787-nm excitation; emission, > 830 nm), short-wavelength autofluorescence (SW-AF; 488-nm excitation, 500-to 680-nm emission), and spectral-domain optical coherence tomography (SD-OCT) images were acquired with a confocal scanning laser ophthalmoscope. SW-AF intensities were measured by quantitative fundus autofluorescence (qAF), and NIR-AF intensity profiles were analyzed. Retinal thicknesses and visual acuity were measured. RESULTS. In 19 of 31 eyes of affected males, islands of preserved NIR-AF signal were also visible as fluorescence signal in SW-AF images. Notable in 12 eyes were areas of speckled SW-AF that was hypoautofluorescent in the NIR-AF image. Islands of preserved NIR-AF and SW-AF signal were often associated with the presence of visible but thinned outer nuclear layer and discontinuous interdigitation zone, ellipsoid zone, and external limiting membrane. NIR-AF profiles revealed that even in areas of preserved retina, the NIR-AF signal from retinal pigment epithelium (RPE) melanin is greatly reduced. qAF was reduced overall. The fundus of carriers was characterized by a mosaicism in which patches of reduced NIR-AF colocalized with reduced SW-AF. CONCLUSIONS. In CHM-affected males, the presence of RPE was indicated by an NIR-AF signal and the absence of hypertransmission of OCT signal into the choroid. RPE preservation was associated with better visual acuity. In carriers, patches of reduced SW-AF colocalized with decreased NIR-AF and qAF was severely reduced.Peer reviewe

Electroretinography Reveals Difference in Cone Function between Syndromic and Nonsyndromic USH2A Patients

Usher syndrome is an inherited and irreversible disease that manifests as retinitis pigmentosa (RP) and bilateral neurosensory hearing loss. Mutations in Usherin 2A (USH2A) are not only a frequent cause of Usher syndrome, but also nonsyndromic RP. Although gene-and cell-based therapies are on the horizon for RP and Usher syndrome, studies characterizing natural disease are lacking. In this retrospective analysis, retinal function of USH2A patients was quantified with electroretinography. Both groups had markedly reduced rod and cone responses, but nonsyndromic USH2A patients had 30 Hz-flicker electroretinogram amplitudes that were significantly higher than syndromic patients, suggesting superior residual cone function. There was a tendency for Usher syndrome patients to have a higher distribution of severe mutations, and alleles in this group had a higher odds of containing nonsense or frame-shift mutations. These data suggest that the previously reported severe visual phenotype seen in syndromic USH2A patients could relate to a greater extent of cone dysfunction. Additionally, a genetic threshold may exist where mutation burden relates to visual phenotype and the presence of hearing deficits. The auditory phenotype and allelic hierarchy observed among patients should be considered in prospective studies of disease progression and during enrollment for future clinical trials.National Institute of HealthNational Cancer InstituteResearch to Prevent Blindness (RPB)RPB, New York, NY, USARPBInternational Council of Ophthalmology - Retina Research FoundationNIHTistou and Charlotte Kerstan FoundationSchneeweiss Stem Cell Fund, New York StateFoundation Fighting Blindness New York Regional Research CenterCrowley Family FundGebroe Family FoundationColumbia Univ, Dept Ophthalmol, Med Ctr, Jonas Childrens Vis Care, New York, NY 10027 USAColumbia Univ, Dept Ophthalmol, Med Ctr, Bernard & Shirlee Brown Glaucoma Lab, New York, NY 10027 USANew York Presbyterian Hosp, Edward S Harkness Eye Inst, New York, NY 10034 USASuny Downstate Med Ctr, Brooklyn, NY 11203 USAUniv Fed Espirito Santo, Dept Ophthalmol, Vitoria, BrazilUniv Fed Sao Paulo, Dept Ophthalmol, Sao Paulo, BrazilColumbia Univ, Dept Biostat, New York, NY USAUniv Montreal, Dept Ophthalmol, Montreal, PQ, CanadaShanghai Jiao Tong Univ, Sch Med, Xin Hua Hosp, Dept Ophthalmol, Shanghai, Peoples R ChinaColumbia Univ, Inst Human Nutr, Dept Pathol & Cell Biol, Stem Cell Initiat CSCI,Coll Phys & Surg, New York, NY 10032 USAStanford Univ, Dept Ophthalmol, Om Lab, Byers Eye Inst, Palo Alto, CA 94304 USAUniv Fed Sao Paulo, Dept Ophthalmol, Sao Paulo, BrazilWeb of Scienc

Multimodal imaging and electroretinography analysis of end-stage presentations of X-linked retinoschisis

Purpose : Patients with X-linked retinoschisis (XLRS) presenting at end-stage of disease are difficult to diagnose when severe macular atrophy is present without intraretinal fluid. The purpose of this study is to characterize late presentations of XLRS with retinal imaging and electrophysiology in patients without pathognomonic fundus exam or OCT findings. Methods : Three unrelated male patients presented by referral to the Harkness Eye Institute electrophysiology clinic for evaluation of severe retinal degenerations of unknown etiology. Ocular exam findings, SD-OCT, fundus autofluorescence (FAF), full-field electroretinography (ffERG), and genetic testing results were retrospectively reviewed. Results : All three patients (average age, 62; range, 58-70) described chronic, progressive bilateral vision loss and exhibited decreased visual acuity and central macular atrophy in both eyes on exam. In each patient (6 eyes), SD-OCT confirmed marked atrophy affecting all retinal layers with no evidence of cystoid changes. FAF imaging revealed a hyperautofluorescent ring between the vascular arcades of all eyes, containing an inner region of heterogenous signal and confluent patches of hypoautofluorescence consistent with loss of retinal pigment epithelium. Disease severity and FAF/OCT phenotype was symmetric between eyes of all patients. FfERGs were performed in two patients and both showed decreased scotopic b-wave and photopic 30 Hz-flicker amplitudes, with electronegative maximum scotopic responses. RS1 mutations were identified in each patient: c.286T\u3eC, (p.Trp96Arg), c.416delA (p.Gln139Argfs*10), and c.445A\u3eC (p.Thr149Pro) respectively, confirming the diagnosis of XLRS. Conclusions : Patients with undiagnosed late-stage XLRS may present with profound macular atrophy but without the classic ‘spoke-wheel’ appearance of the fundus or characteristic foveal schisis, thus delaying accurate diagnosis. Patients suspected to have an inherited retinal dystrophy that exhibit severe macular degeneration and electronegative responses on ffERG may warrant screening with candidate RS1 gene testing as a first diagnostic step

Novel Mutation in Retinitis Pigmentosa GTPase Regulator Gene Causes Primary Ciliary Dyskinesia and Retinitis Pigmentosa.

The majority of X-linked retinitis pigmentosa (XLRP) is due to mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene. Determining the pathogenicity of novel variants is important for enrollment of patients into gene therapy trials. Sequencing and analysis of RPGR variants in ORF15 is challenging, as it is highly repetitive and rich in purines. Overlapping reading frames and polymorphic insertions / deletions add further complexity to the detection of mutations. Identifying systemic manifestations in affected males and carrier phenotype in related females expedites confirmation of pathogenic variants. The authors present a 16-year-old boy with a history of primary ciliary dyskinesia presenting with complaints of nyctalopia and visual field constriction. Multimodal imaging found peripheral thinning of the retina and a characteristic foveal hyperautofluorescent ring in the proband, and a carrier phenotype in the asymptomatic mother. A novel c.1059_1059+2delGGT, p.(?) variant in RPGR was identified as hemizygous in the affected boy and heterozygous in his mother. This case study expands the genotypic spectrum of RPGR variants associated with systemic manifestations. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:548-552.]