Sharon B Schwartz

University of Pennsylvania, Filadelfia, Pennsylvania, United States

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Publications (60)394.9 Total impact

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    ABSTRACT: Retinal gene therapy for Leber’s congenital amaurosis, an autosomal recessive childhood blindness, has been widely considered to be safe and efficacious. Three years after therapy, improvement in vision was maintained, but the rate of loss of photoreceptors in the treated retina was the same as that in the untreated retina. Here we describe long-term follow-up data from three treated patients. Topographic maps of visual sensitivity in treated regions, nearly 6 years after therapy for two of the patients and 4.5 years after therapy for the third patient, indicate progressive diminution of the areas of improved vision.
    New England Journal of Medicine 05/2015; DOI:10.1056/NEJMoa1412965 · 54.42 Impact Factor
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    PLoS ONE 04/2015; 10(4):e0125700. DOI:10.1371/journal.pone.0125700 · 3.53 Impact Factor
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    ABSTRACT: Mutations in the ABCA4 gene are a common cause of autosomal recessive retinal degeneration. All mouse models to date are based on knockouts of Abca4, even though the disease is often caused by missense mutations such as the complex allele L541P;A1038V (PV). We now show that the PV mutation causes severe human disease whereas the V mutation alone causes mild disease. Mutant ABCA4 proteins expressed heterologously in mammalian cells retained normal cellular localization. However, basal and all-trans-retinal-stimulated ATPase activities were reduced substantially for P and PV but only mildly for V. Electron microscopy revealed marked structural changes and misfolding for the P and PV mutants but few changes for the V mutant, consistent with the disease severity difference in patients. We generated Abca4(PV/PV) knock-in mice homozygous for the complex PV allele to investigate the effects of this misfolding mutation in vivo. Mutant ABCA4 RNA approximated WT ABCA4 RNA levels but, surprisingly, only trace amounts of mutant ABCA4 protein were noted in the retina. RNA sequencing of WT, Abca4(-/-) and Abca4(PV/PV) mice revealed gene expression alterations in the retina and RPE. Similar to Abca4(-/-) mice, Abca4(PV/PV) mice showed substantial A2E and lipofuscin accumulation in their RPE cells but no retinal degeneration up to 12 months of age. Thus, rapid degradation of this large misfolded mutant protein in mouse retina caused little detectable photoreceptor degeneration. These findings suggest likely differences in the unfolded protein response between murine and human photoreceptors, and clinical treatments directed at increasing this capability. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
    Human Molecular Genetics 02/2015; 24(11). DOI:10.1093/hmg/ddv073 · 6.68 Impact Factor
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    ABSTRACT: Achromatopsia (ACHM) is a congenital, autosomal recessive retinal disease that manifests cone dysfunction, reduced visual acuity and color vision, nystagmus, and photoaversion. Five genes are known causes of ACHM. The present study took steps toward performing a trial of gene therapy in ACHM by characterizing the genetics of ACHM in Israel and the Palestinian Territories and analyzing retinal function and structure in CNGA3 ACHM patients from the Israeli-Palestinian population and US patients with other origins. Case series study. Patients with clinically suspected ACHM, cone dysfunction phenotypes, and unaffected family members were included. The protocol was approved by the local institutional review board and informed consent was obtained from all participants. Genetic analyses included homozygosity mapping and exome sequencing. Phenotype was assessed with electroretinography (ERG), optical coherence tomography, psychophysics, and photoaversion testing. Single nucleotide polymorphism microarray, exome analysis, DNA sequence analysis, visual function testing including ERG, and photoaversion. We identified 148 ACHM patients from 57 Israeli and Palestinian families; there were 16 CNGA3 mutations (5 novel) in 41 families and 5 CNGB3 mutations (1 novel) in 8 families. Two CNGA3 founder mutations underlie >50% of cases. These mutations lead to a high ACHM prevalence of ∼1:5000 among Arab-Muslims residing in Jerusalem. Rod ERG abnormalities (in addition to cone dysfunction) were detected in 59% of patients. Retinal structure in CNGA3 ACHM patients revealed persistent but abnormal foveal cones. Under dark- and light-adapted conditions, patients use rod-mediated pathways. Photoaversion was readily demonstrated with transition from the dark to a dim light background. Among Israeli and Palestinian patients, CNGA3 mutations are the leading cause of ACHM. Retinal structural results support the candidacy of CNGA3 ACHM for clinical trials for therapy of cone photoreceptors. Efficacy outcome measures would include chromatic light-adapted psychophysics, with attention to the photoreceptor basis of the response, and quantitation of photoaversion. Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.
    Ophthalmology 01/2015; 122(5). DOI:10.1016/j.ophtha.2014.11.025 · 6.17 Impact Factor
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    ABSTRACT: Purpose: To evaluate fixation location and oculomotor characteristics of 15 RPE65-LCA patients undergoing retinal gene therapy. Methods: Eye movements were quantified under infrared imaging of the retina while the subject fixated on a stationary target. In a subset of patients, letter recognition under retinal imaging was performed. Cortical responses to visual stimulation were measured using functional MRI in two patients before and after therapy. Results: All patients could fixate on a 1o diameter visible target in the dark. The preferred retinal locus of fixation could be at the anatomical fovea or at an extra-foveal locus. There was a wide range of oculomotor abnormalities. Natural history showed little change in oculomotor abnormalities if target illuminance was increased to maintain target visibility as the disease progressed. 11/15 study eyes with gene therapy showed no difference from baseline fixation location or instability over an average of 3.5 years followup. 4/15 eyes developed new pseudo-foveas in the treated retinal regions 9 to 12 months following therapy that persisted up to 6 years; patients used their pseudo-foveas for letter identification. fMRI studies demonstrated preservation of light sensitivity was restricted to the cortical projection zone of the pseudo-foveas. Conclusions: The slow emergence of pseudo-foveas many months following the initial increases in light sensitivity point to a substantial plasticity of the adult visual system and a complex interaction between it and the progression of underlying retinal disease. The visual significance of pseudo-foveas suggests careful consideration of treatment zones for future gene therapy trials. Copyright © 2014 by Association for Research in Vision and Ophthalmology.
    Investigative Ophthalmology &amp Visual Science 12/2014; 56(1). DOI:10.1167/iovs.14-15895 · 3.66 Impact Factor
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    ABSTRACT: PURPOSE. To investigate visual function and outer and inner retinal structure in the rare form of retinal degeneration (RD) caused byTULP1 (tubby-like protein 1) mutations. METHODS. RD patients with TULP1 mutations (n=5; age range, 5-36 years) were studied by kinetic and chromatic static perimetry, en face autofluoresence imaging and spectral-domain optical coherence tomography (OCT) scans. Outer and inner retinal laminar thickness were measured and mapped across the central retina. Comparisons were made with results from patients with RD associated with four ciliopathy genotypes (MAK, RPGR, BBS1 and USH2A). RESULTS. The TULP1-RD patients were severely affected already in the first decade of life and there was rapidly progressive visual loss. No evidence of rod function was present at any age. Small central islands showed melanized retinal pigment epithelium by autofluorescence imaging and well-preserved photoreceptor laminar thickness by OCT imaging. There was extracentral loss of laminar architecture and increased inner retinal thickening. Structure-function relationships in residual foveal cone islands were made in TULP1-RD patients and in other retinopathies considered ciliopathies. TULP1-RD patients, unlike the others, had greater dysfunction for the degree of foveal structural preservation. CONCLUSIONS. TULP1-RD leads to a small central island of residual foveal cones at early ages. These cones are less sensitive than expected from the residual structure. The human phenotype is consistent with experimental evidence in the Tulp1 knockout mouse model that visual dysfunction could be complicated by abnormal processes proximal to cone outer segments.
    Investigative Ophthalmology &amp Visual Science 07/2014; 55(8). DOI:10.1167/iovs.14-14570 · 3.66 Impact Factor
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    ABSTRACT: ABSTRACT PURPOSE. To investigate in vivo inner and outer retinal microstructure and effects of structural abnormalities on visual function in patients with retinal degeneration caused by ABCA4 mutations (ABCA4-RD). METHODS. Patients with ABCA4-RD (n=45; age range, 9-71 years) were studied by spectral-domain optical coherence tomography (OCT) scans extending from the fovea to 30 degrees eccentricity along horizontal and vertical meridians. Thicknesses of outer and inner retinal laminae were analyzed. Serial OCT measurements available over a mean period of 4 years (range,2-8) allowed examination of the progression of outer and inner retinal changes. A subset of patients had dark-adapted chromatic static threshold perimetry. RESULTS.There was a spectrum of photoreceptor layer thickness changes from localized central retinal abnormalities to extensive thinning across central and near mid-peripheral retina. The inner retina also showed changes: there was thickening of the inner nuclear layer (INL) that was mainly associated with regions of photoreceptor loss. Serial data documented only limited change in some patients while others showed an increase in ONL thinning accompanied by increased INL thickening in some regions imaged. Visual function in regions with and without INL thickening were both describable with a previously-defined model based on photoreceptor quantum catch. CONCLUSIONS. Inner retinal laminar abnormalities, as in other human photoreceptor diseases, can be a feature of ABCA4-RD. These changes are likely due to the retinal remodeling that accompanies photoreceptor loss. Rod photoreceptor-mediated visual loss in retinal regions with inner laminopathy at the stages studied did not exceed the prediction from photoreceptor loss alone.
    Investigative ophthalmology & visual science 02/2014; 55(3). DOI:10.1167/iovs.13-13768 · 3.66 Impact Factor
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    ABSTRACT: Human X-linked blue-cone monochromacy (BCM), a disabling congenital visual disorder of cone photoreceptors, is a candidate disease for gene augmentation therapy. BCM is caused by either mutations in the red (OPN1LW) and green (OPN1MW) cone photoreceptor opsin gene array or large deletions encompassing portions of the gene array and upstream regulatory sequences that would predict a lack of red or green opsin expression. The fate of opsin-deficient cone cells is unknown. We know that rod opsin null mutant mice show rapid postnatal death of rod photoreceptors. We studied a cohort of 20 BCM patients (ages 5-58) with large deletions in the red/green opsin gene array using in vivo histology with high resolution retinal imaging. Already in the first years of life, retinal structure was not normal: there was partial loss of photoreceptors across the central retina. Remaining cone cells had detectable outer segments that were abnormally shortened. Adaptive optics imaging confirmed existence of inner segments at a spatial density greater than that expected for the residual blue cones. The evidence indicates that human cones in patients with deletions in the red/green opsin gene array can survive in reduced numbers with limited outer segment material, suggesting potential value of gene therapy for BCM.
    Human gene therapy 09/2013; 24(12). DOI:10.1089/hum.2013.153 · 3.62 Impact Factor
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    ABSTRACT: SignificanceThe first retinal gene therapy in human blindness from RPE65 mutations has focused on safety and efficacy, as defined by improved vision. The disease component not studied, however, has been the fate of photoreceptors in this progressive retinal degeneration. We show that gene therapy improves vision for at least 3 y, but photoreceptor degeneration progresses unabated in humans. In the canine model, the same result occurs when treatment is at the disease stage equivalent to humans. The study shows the need for combinatorial therapy to improve vision in the short term but also slow retinal degeneration in the long term.
    Proceedings of the National Academy of Sciences 01/2013; 110(6). DOI:10.1073/pnas.1218933110 · 9.81 Impact Factor
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    ABSTRACT: PURPOSE. To determine the intervisit variability of kinetic visual fields and visual acuity in patients with Leber congenital amaurosis (LCA) caused by mutations in the RPE65 (Retinal Pigment Epithelium-specific Protein 65kDa) gene. METHODS. RPE65-LCA patients (n=20; ages11-40 years) were studied on at least two visits separated by <120 days using Goldmann visual field (GVF) and ETDRS visual acuity (VA) in a retrospective review. GVFs were quantified by computing the spherical coordinates of their vertices and calculating the solid angle subtended, and reported in normalized solid-angle units (nsu) as percent of average normal field extent. Repeatability coefficients were calculated using 95% confidence intervals on log10-converted variables. RESULTS. Visual field extents in RPE65-LCA spanned a wide range from 4 to 95 nsu. The repeatability coefficient was 0.248 (log10nsu) suggesting cutoffs for significant change (in nsu) of +77% for improvement and -44% for worsening. VA in RPE65-LCA ranged from logMAR = 0.14 to 1.96 (20/40 to 20/1250). The repeatability coefficient was 0.170 (logMAR) (±8.5 ETDRS letters). Comparisons with published studies of ungenotyped retinitis pigmentosa (RP) showed that the RPE65-LCA patients had higher variability in kinetic field extent. VA variability in RPE65-LCA fell within reported results for RP. CONCLUSIONS. Variability data for GVF and VA are provided to permit interpretation of the significance of increases and decreases of these functional outcomes in ongoing and planned clinical trials of therapy for LCA caused by RPE65 mutations.
    Investigative ophthalmology & visual science 01/2013; 54(2). DOI:10.1167/iovs.12-11341 · 3.66 Impact Factor
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    ABSTRACT: Congenital stationary night blindness (CSNB) is a clinically and genetically heterogeneous retinal disorder. Two forms can be distinguished clinically: complete CSNB (cCSNB) and incomplete CSNB. Individuals with cCSNB have visual impairment under low-light conditions and show a characteristic electroretinogram (ERG). The b-wave amplitude is severely reduced in the dark-adapted state of the ERG, representing abnormal function of ON bipolar cells. Furthermore, individuals with cCSNB can show other ocular features such as nystagmus, myopia, and strabismus and can have reduced visual acuity and abnormalities of the cone ERG waveform. The mode of inheritance of this form can be X-linked or autosomal recessive, and the dysfunction of four genes (NYX, GRM6, TRPM1, and GPR179) has been described so far. Whole-exome sequencing in one simplex cCSNB case lacking mutations in the known genes led to the identification of a missense mutation (c.983G>A [p.Cys328Tyr]) and a nonsense mutation (c.1318C>T [p.Arg440(∗)]) in LRIT3, encoding leucine-rich-repeat (LRR), immunoglobulin-like, and transmembrane-domain 3 (LRIT3). Subsequent Sanger sequencing of 89 individuals with CSNB identified another cCSNB case harboring a nonsense mutation (c.1151C>G [p.Ser384(∗)]) and a deletion predicted to lead to a premature stop codon (c.1538_1539del [p.Ser513Cysfs(∗)59]) in the same gene. Human LRIT3 antibody staining revealed in the outer plexiform layer of the human retina a punctate-labeling pattern resembling the dendritic tips of bipolar cells; similar patterns have been observed for other proteins implicated in cCSNB. The exact role of this LRR protein in cCSNB remains to be elucidated.
    The American Journal of Human Genetics 12/2012; 92(1). DOI:10.1016/j.ajhg.2012.10.023 · 10.99 Impact Factor
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    ABSTRACT: PURPOSE: To determine the proportion of male patients presenting as simplex retinal degenerative disease (RD) [retinitis pigmentosa (RP) or cone/cone-rod dystrophy (COD/CORD)] with mutations in the X-linked retinal degeneration genes - RPGR and RP2. METHODS: Simplex males were defined as patients with no known affected family members. Patients were excluded if they had a family history of parental consanguinity. Blood samples from a total of 214 simplex males with a diagnosis of retinal degeneration were collected for genetic analysis. The patients were screened for mutations in RPGR and RP2 by direct sequencing of PCR-amplified genomic DNA. RESULTS: We identified pathogenic mutations in 32 of the 214 patients screened (15%). Of the 29 patients with a diagnosis of COD/CORD, four mutations were identified in the ORF15 mutational hotspot of the RPGR gene. Of the 185 RP patients, 3 patients had mutations in RP2 and 25 had RPGR mutations (including 12 in the ORF15 region). CONCLUSIONS: This study represents mutation screening of RPGR and RP2 in the largest cohort, to date, of simplex males affected with RP or COD/CORD. Our results demonstrate a substantial contribution of RPGR mutations to retinal degenerations, and in particular, to simplex RP. Based on our findings, we suggest that RPGR should be considered as a first tier gene for screening isolated males affected with retinal degeneration.
    Investigative ophthalmology & visual science 11/2012; 53(13). DOI:10.1167/iovs.12-11025 · 3.66 Impact Factor
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    ABSTRACT: The GUCY2D gene encodes retinal membrane guanylyl cyclase (RetGC1), a key component of the phototransduction machinery in photoreceptors. Mutations in GUCY2D cause Leber congenital amaurosis type 1 (LCA1), an autosomal recessive human retinal blinding disease. The effects of RetGC1 deficiency on human rod and cone photoreceptor structure and function are currently unknown. To move LCA1 closer to clinical trials, we characterized a cohort of patients (ages 6 months-37 years) with GUCY2D mutations. In vivo analyses of retinal architecture indicated intact rod photoreceptors in all patients but abnormalities in foveal cones. By functional phenotype, there were patients with and those without detectable cone vision. Rod vision could be retained and did not correlate with the extent of cone vision or age. In patients without cone vision, rod vision functioned unsaturated under bright ambient illumination. In vitro analyses of the mutant alleles showed that in addition to the major truncation of the essential catalytic domain in RetGC1, some missense mutations in LCA1 patients result in a severe loss of function by inactivating its catalytic activity and/or ability to interact with the activator proteins, GCAPs. The differences in rod sensitivities among patients were not explained by the biochemical properties of the mutants. However, the RetGC1 mutant alleles with remaining biochemical activity in vitro were associated with retained cone vision in vivo. We postulate a relationship between the level of RetGC1 activity and the degree of cone vision abnormality, and argue for cone function being the efficacy outcome in clinical trials of gene augmentation therapy in LCA1.
    Human Molecular Genetics 10/2012; 22(1). DOI:10.1093/hmg/dds421 · 6.68 Impact Factor
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    ABSTRACT: We investigated the retinal disease due to mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene in human patients and in an Rpgr conditional knockout (cko) mouse model. XLRP patients with RPGR-ORF15 mutations (n = 35, ages at first visit 5-72 years) had clinical examinations, and rod and cone perimetry. Rpgr-cko mice, in which the proximal promoter and first exon were deleted ubiquitously, were back-crossed onto a BALB/c background, and studied with optical coherence tomography and electroretinography (ERG). Retinal histopathology was performed on a subset. Different patterns of rod and cone dysfunction were present in patients. Frequently, there were midperipheral losses with residual rod and cone function in central and peripheral retina. Longitudinal data indicated that central rod loss preceded peripheral rod losses. Central cone-only vision with no peripheral function was a late stage. Less commonly, patients had central rod and cone dysfunction, but preserved, albeit abnormal, midperipheral rod and cone vision. Rpgr-cko mice had progressive retinal degeneration detectable in the first months of life. ERGs indicated relatively equal rod and cone disease. At late stages, there was greater inferior versus superior retinal degeneration. RPGR mutations lead to progressive loss of rod and cone vision, but show different patterns of residual photoreceptor disease expression. Knowledge of the patterns should guide treatment strategies. Rpgr-cko mice had onset of degeneration at relatively young ages and progressive photoreceptor disease. The natural history in this model will permit preclinical proof-of-concept studies to be designed and such studies should advance progress toward human therapy.
    Investigative ophthalmology & visual science 07/2012; 53(9):5594-608. DOI:10.1167/iovs.12-10070 · 3.66 Impact Factor
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    ABSTRACT: To measure macular visual function in patients with unstable fixation, to define the photoreceptor source of this function, and to estimate its test-retest repeatability as a prerequisite to clinical trials. Patients (n = 38) with ABCA4-associated retinal degeneration (RD) or with retinitis pigmentosa (RP) were studied with retina-tracking microperimetry along the foveo-papillary profile between the fovea and the optic nerve head, and point-by-point test-retest repeatability was estimated. A subset with foveal fixation was also studied with dark-adapted projection perimetry using monochromatic blue and red stimuli along the horizontal meridian. Macular function in ABCA4-RD patients transitioned from lower sensitivity at the parafovea to higher sensitivity in the perifovea. RP patients had the inverse pattern. Red-on-red microperimetric sensitivities successfully avoided ceiling effects and were highly correlated with absolute sensitivities. Point-by-point test-retest limits (95% confidence intervals) were ±4.2 dB; repeatability was not related to mean sensitivity, eccentricity from the fovea, age, fixation location, or instability. Repeatability was also not related to the local slope of sensitivity and was unchanged in the parapapillary retina. Microperimetry allows reliable testing of macular function in RD patients without foveal fixation in longitudinal studies evaluating natural disease progression or efficacy of therapeutic trials. A single estimate of test-retest repeatability can be used to determine significant changes in visual function at individual retinal loci within diseased regions that are homogeneous and those that are heterogeneous and also in transition zones at high risk for disease progression.
    Investigative ophthalmology & visual science 02/2012; 53(2):841-52. DOI:10.1167/iovs.11-8415 · 3.66 Impact Factor
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    ABSTRACT: Autosomal recessive retinitis pigmentosa (RP), a heterogeneous group of degenerations of the retina, can be due to mutations in the MFRP (membrane-type frizzled-related protein) gene. A patient with RP with MFRP mutations, one of which is novel and the first splice site mutation reported, was characterized by noninvasive retinal and visual studies. The phenotype, albeit complex, suggested that this retinal degeneration may be a candidate for gene-based therapy. Proof-of-concept studies were performed in the rd6 Mfrp mutant mouse model. The fast-acting tyrosine-capsid mutant AAV8 (Y733F) vector containing the small chicken β-actin promoter driving the wild-type mouse Mfrp gene was used. Subretinal vector delivery on postnatal day 14 prevented retinal degeneration. Treatment rescued rod and cone photoreceptors, as assessed by electroretinography and retinal histology at 2 months of age. This AAV-mediated gene delivery also resulted in robust MFRP expression predominantly in its normal location within the retinal pigment epithelium apical membrane and its microvilli. The clinical features of MFRP-RP and our preliminary data indicating a response to gene therapy in the rd6 mouse suggest that this form of RP is a potential target for gene-based therapy.
    Human gene therapy 12/2011; 23(4):367-76. DOI:10.1089/hum.2011.169 · 3.62 Impact Factor
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    ABSTRACT: To determine the disease expression in autosomal recessive (ar) retinitis pigmentosa (RP) caused by mutations in the MAK (male germ cell-associated kinase) gene. Patients with RP and MAK gene mutations (n = 24; age, 32-77 years at first visit) were studied by ocular examination, perimetry, and optical coherence tomography (OCT). All but one MAK patient were homozygous for an identical truncating mutation in exon 9 and had Ashkenazi Jewish heritage. The carrier frequency of this mutation among 1207 unrelated Ashkenazi control subjects was 1 in 55, making it the most common cause of heritable retinal disease in this population and MAK-associated RP the sixth most common Mendelian disease overall in this group. Visual acuities could be normal into the eighth decade of life. Kinetic fields showed early loss in the superior-temporal quadrant. With more advanced disease, superior and midperipheral function was lost, but the nasal field remained. Only a central island was present at late stages. Pigmentary retinopathy was less prominent in the superior nasal quadrant. Rod-mediated vision was abnormal but detectable in the residual field; all patients had rod>cone dysfunction. Photoreceptor layer thickness was normal centrally but decreased with eccentricity. At the stages studied, there was no evidence of photoreceptor ciliary elongation. The patterns of disease expression in the MAK form of arRP showed some resemblance to patterns described in autosomal dominant RP, especially the form caused by RP1 mutations. The similarity in phenotypes is of interest, considering that there is experimental evidence of interaction between Mak and RP1 in the photoreceptor cilium.
    Investigative ophthalmology & visual science 11/2011; 52(13):9665-73. DOI:10.1167/iovs.11-8527 · 3.66 Impact Factor
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    ABSTRACT: To determine the safety and efficacy of subretinal gene therapy in the RPE65 form of Leber congenital amaurosis using recombinant adeno-associated virus 2 (rAAV2) carrying the RPE65 gene. Open-label, dose-escalation phase I study of 15 patients (range, 11-30 years of age) evaluated after subretinal injection of the rAAV2- RPE65 vector into the worse-functioning eye. Five cohorts represented 4 dose levels and 2 different injection strategies. Primary outcomes were systemic and ocular safety. Secondary outcomes assayed visual function with dark-adapted full-field sensitivity testing and visual acuity with Early Treatment Diabetic Retinopathy Study charts. Further assays included immune responses to the vector, static visual fields, pupillometry, mobility performance, and optical coherence tomography. No systemic toxicity was detected; ocular adverse events were related to surgery. Visual function improved in all patients to different degrees; improvements were localized to treated areas. Cone and rod sensitivities increased significantly in the study eyes but not in the control eyes. Minor acuity improvements were recorded in many study and control eyes. Major acuity improvements occurred in study eyes with the lowest entry acuities and parafoveal fixation loci treated with subretinal injections. Other patients with better foveal structure lost retinal thickness and acuity after subfoveal injections. Gene therapy for Leber congenital amaurosis caused by RPE65 mutations is sufficiently safe and substantially efficacious in the extrafoveal retina. There is no benefit and some risk in treating the fovea. No evidence of age-dependent effects was found. Our results point to specific treatment strategies for subsequent phases. Gene therapy for inherited retinal disease has the potential to become a future part of clinical practice. clinicaltrials.gov Identifier: NCT00481546.
    Archives of ophthalmology 09/2011; 130(1):9-24. DOI:10.1001/archophthalmol.2011.298 · 4.49 Impact Factor
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    ABSTRACT: PURPOSE. To determine the disease course in Usher syndrome type IB (USH1B) caused by myosin 7A (MYO7A) gene mutations. METHODS. USH1B patients (n = 33, ages 2-61) representing 25 different families were studied by ocular examination, kinetic and chromatic static perimetry, dark adaptometry, and optical coherence tomography (OCT). Consequences of the mutant alleles were predicted. RESULTS. All MYO7A patients had severely abnormal ERGs, but kinetic fields revealed regional patterns of visual loss that suggested a disease sequence. Rod-mediated vision could be lost to different degrees in the first decades of life. Cone vision followed a more predictable and slower decline. Central vision ranged from normal to reduced in the first four decades of life and thereafter was severely abnormal. Dark adaptation kinetics was normal. Photoreceptor layer thickness in a wide region of central retina could differ dramatically between patients of comparable ages; and there were examples of severe losses in childhood as well as relative preservation in patients in the third decade of life. Comparisons were made between the mutant alleles in mild versus more severe phenotypes. CONCLUSIONS. A disease sequence in USH1B leads from generally full but impaired visual fields to residual small central islands. At most disease stages, there was preserved temporal peripheral field, a potential target for early phase clinical trials of gene therapy. From data comparing patients' rod disease in this cohort, the authors speculate that null MYO7A alleles could be associated with milder dysfunction and fewer photoreceptor structural losses at ages when other genotypes show more severe phenotypes.
    Investigative ophthalmology & visual science 08/2011; 52(11):7924-36. DOI:10.1167/iovs.11-8313 · 3.66 Impact Factor
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    ABSTRACT: To investigate the human disease due to CRB1 mutations and compare results with the Crb1-mutant rd8 mouse. Twenty-two patients with CRB1 mutations were studied. Function was assessed with perimetry and electroretinography (ERG) and retinal structure with optical coherence tomography (OCT). Cortical structure and function were quantified with magnetic resonance imaging (MRI). Rd8 mice underwent ERG, OCT, and retinal histopathology. Visual acuities ranged from 20/25 to light perception. Rod ERGs were not detectable; small cone signals were recordable. By perimetry, small central visual islands were separated by midperipheral scotomas from far temporal peripheral islands. The central islands were cone mediated, whereas the peripheral islands retained some rod function. With OCT, there were small foveal islands of thinned outer nuclear layer (ONL) surrounded by thick delaminated retina with intraretinal hyperreflective lesions. MRI showed structurally normal optic nerves and only subtle changes to occipital lobe white and gray matter. Functional MRI indicated that whole-brain responses from patients were of reduced amplitude and spatial extent compared with those of normal controls. Rd8 mice had essentially normal ERGs; OCT and histopathology showed patchy retinal disorganization with pseudorosettes more pronounced in ventral than in dorsal retina. Photoreceptor degeneration was associated with dysplastic regions. CRB1 mutations lead to early-onset severe loss of vision with thickened, disorganized, nonseeing retina. Impaired peripheral vision can persist in late disease stages. Rd8 mice also have a disorganized retina, but there is sufficient photoreceptor integrity to produce largely normal retinal function. Differences between human and mouse diseases will complicate proof-of-concept studies intended to advance treatment initiatives.
    Investigative ophthalmology & visual science 07/2011; 52(9):6898-910. DOI:10.1167/iovs.11-7701 · 3.66 Impact Factor

Publication Stats

3k Citations
394.90 Total Impact Points

Institutions

  • 2003–2015
    • University of Pennsylvania
      • Department of Ophthalmology
      Filadelfia, Pennsylvania, United States
  • 2009–2014
    • William Penn University
      Filadelfia, Pennsylvania, United States
  • 2010–2011
    • Hebrew University of Jerusalem
      • Department of Ophthalmology
      Jerusalem, Jerusalem District, Israel
  • 2008–2011
    • University of Florida
      • Department of Ophthalmology
      Gainesville, FL, United States
  • 2007
    • University of Iowa
      Iowa City, Iowa, United States