Macular Microcysts in Mitochondrial Optic Neuropathies: Prevalence and Retinal Layer Thickness Measurements.

PurposeTo investigate the thickness of the retinal layers and to assess the prevalence of macular microcysts (MM) in the inner nuclear layer (INL) of patients with mitochondrial optic neuropathies (MON).MethodsAll patients with molecularly confirmed MON, i.e. Leber's Hereditary Optic Neuropathy (LHON) and Dominant Optic Atrophy (DOA), referred between 2010 and 2012 were enrolled. Eight patients with MM were compared with two control groups: MON patients without MM matched by age, peripapillary retinal nerve fiber layer (RNFL) thickness, and visual acuity, as well as age-matched controls. Retinal segmentation was performed using specific Optical coherence tomography (OCT) software (Carl Zeiss Meditec). Macular segmentation thickness values of the three groups were compared by one-way analysis of variance with Bonferroni post hoc corrections.ResultsMM were identified in 5/90 (5.6%) patients with LHON and 3/58 (5.2%) with DOA. The INL was thicker in patients with MON compared to controls regardless of the presence of MM [133.1±7μm vs 122.3±9μm in MM patients (p<0.01) and 128.5±8μm vs. 122.3±9μm in no-MM patients (p<0.05)], however the outer nuclear layer (ONL) was thicker in patients with MM (101.4±1mμ) compared to patients without MM [77.5±8mμ (p<0.001)] and controls [78.4±7mμ (p<0.001)]. ONL thickness did not significantly differ between patients without MM and controls.ConclusionThe prevalence of MM in MON is low (5-6%), but associated with ONL thickening. We speculate that in MON patients with MM, vitreo-retinal traction contributes to the thickening of ONL as well as to the production of cystic spaces

Variation in OPA1 does not explain the incomplete penetrance of Leber hereditary optic neuropathy

Purpose: Leber hereditary optic neuropathy (LHON) is a common cause of inherited blindness, primarily due to one of three mitochondrial DNA (mtDNA) mutations. These mtDNA pathogenic mutations have variable clinical penetrance. Recent linkage evidence raised the possibility that the nuclear gene optic atrophy 1 (OPA1) determines whether mtDNA mutation carriers develop blindness. To validate these findings we studied OPA1 in three independent LHON cohorts: sequencing the gene in discordant male sib pairs, carrying out a family-based association study of common functional genetic variants, and carrying out a population-based association study of the same genetic variants.Methods: We tested 3 hypothesis in three separate study groups. Study group 1: Direct sequencing of OPA1 coding regions was performed using sequencing methodologies (Applied Biosystems, Foster City, CA). Chromatograms were compared with the GenBank reference sequence NM_015560.1. Splice-site prediction was performed using GeneSplicer. Study group 2: Genotyping for rs166850 and rs10451941 was performed by restriction fragment length polymorphism (RFLP) analysis with specific primers for both genotypes, using The restriction enzymes RsaI and FspBI to discriminate genotypes. Study group 3: Genotyping for rs166850 and rs10451941 was performed by primer extension of allele-specific extensions products by matrix-associated laser desorption/ionisation time-of-flight (MALDI-TOF, Seqeunom, San Diego, CA) mass spectrometry. Allele and genotype frequencies were compared using Pearson's chi-square test. Multiple logistic regression was performed to look for interactions between the variables. All analyses were performed using SPSS software version 17.0 (SPSS Inc.).Results: In all three groups we were unable to find an association between OPA1 genetic variation and visual failure in LHON mtDNA mutation carriers.Conclusions: Our findings suggest that genetic variation in OPA1 is unlikely to make a major contribution to the risk of blindness in LHON mutation carriers.Medical Research Council (UK)UK Parkinson Disease SocietyUK NIHR Biomedical Research Centre for Aging and AgeTelethon-ItalyNewcastle Univ, Inst Human Genet, Newcastle Upon Tyne NE1 3BZ, Tyne & Wear, EnglandRoyal Victoria Infirm, Dept Ophthalmol, Newcastle Upon Tyne NE1 4LP, Tyne & Wear, EnglandUniv Bologna, Dept Neurol Sci, Bologna, ItalyUniv Fed Sao Paulo, UNIFESP, Dept Oftalmol, Sao Paulo, BrazilFdn Neurol Inst C Besta, Unit Mol Neurogenet, Milan, ItalyUniv Fed Sao Paulo, UNIFESP, Dept Oftalmol, Sao Paulo, BrazilTelethon-Italy: GGP06233Web of Scienc

Retinal function in patients with the neuronal ceroid lipofuscinosis phenotype

Purpose: To analyze the clinical features, visual acuity, and full-field electroretinogram (ERG) findings of 15 patients with the neuronal ceroid lipofuscinosis (NCL) phenotype and to establish the role of ERG testing in NCL diagnosis. Methods: The medical records of five patients with infantile NCL, five with Jansky-Bielschowsky disease, and five with juvenile NCL who underwent full-field ERG testing were retrospectively analyzed. Results: Progressive vision loss was the initial symptom in 66.7% of patients and was isolated or associated with ataxia, epilepsy, and neurodevelopmental involution. Epilepsy was present in 93.3% of patients, of whom 86.6% presented with neurodevelopmental involution. Fundus findings ranged from normal to pigmentary/atrophic abnormalities. Cone-rod, rod-cone, and both types of dysfunction were observed in six, one, and eight patients, respectively. Conclusion: In our study, all patients with the NCL phenotype had abnormal ERG findings, and the majority exhibited both cone-rod and rod-cone dysfunction. We conclude that ERG is a valuable tool for the characterization of visual dysfunction in patients with the NCL phenotype and is useful for diagnosis.Univ Fed Sao Paulo, Escola Paulista Med, Lab Eletrofisiol Visual Clin, Dept Oftalmol & Ciencias Visuais, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Escola Paulista Med, Lab Eletrofisiol Visual Clin, Dept Oftalmol & Ciencias Visuais, Sao Paulo, SP, BrazilWeb of Scienc

The Photopic Negative Response: An Objective Measure of Retinal Ganglion Cell Function in Patients With Leber's Hereditary Optic Neuropathy

Purpose: The photopic negative response (PhNR) is a slow negative component of a flash photopic full-field ERG that has been shown to be specific for retinal ganglion cell (RGC) activity. Direct evaluation of RGC function is desirable in patients with Leber's hereditary optic neuropathy (LHON) in which the loss of central acuity can make it difficult to monitor patients with standard metrics. The purpose of this study was to evaluate the use of PhNR as an objective noninvasive clinical metric in LHON.Methods: Full-field photopic ERG recordings were collected in subjects with the mt.11778G>A/ND4 LHON mutation using a red on blue stimulus. The PhNR was identified using a computer-based automated detection system, and data were manually examined to remove movement artifacts.Results: The PhNR amplitude was compared between controls (n = 13), carriers (n = 17), and affected (n = 6). Mean PhNR amplitude decreased significantly across groups (P < 0.0001). Post hoc Tukey's test revealed a significant decrease in PhNR amplitude between carriers and controls (P < 0.05) and between carriers and affected (P < 0.01).Conclusions: We are able to demonstrate that the PhNR amplitude is significantly decreased in patients affected by LHON compared to carriers in a well-described pedigree. Surprisingly, there was also a decrease in PhNR in carriers, suggesting potential subclinical RGC dysfunction in some carriers. This is important in patients affected with LHON who typically have a dense central scotoma. The PhNR may be a useful objective outcome measure for future clinical trials

Pathological mitophagy disrupts mitochondrial homeostasis in Leber's hereditary optic neuropathy

Leber's hereditary optic neuropathy (LHON), a disease associated with a mitochondrial DNA mutation, is characterized by blindness due to degeneration of retinal ganglion cells (RGCs) and their axons, which form the optic nerve. We show that a sustained pathological autophagy and compartment-specific mitophagy activity affects LHON patient-derived cells and cybrids, as well as induced pluripotent-stem-cell-derived neurons. This is variably counterbalanced by compensatory mitobiogenesis. The aberrant quality control disrupts mitochondrial homeostasis as reflected by defective bioenergetics and excessive reactive oxygen species production, a stress phenotype that ultimately challenges cell viability by increasing the rate of apoptosis. We counteract this pathological mechanism by using autophagy regulators (clozapine and chloroquine) and redox modulators (idebenone), as well as genetically activating mitochondrial biogenesis (PGC1-α overexpression). This study substantially advances our understanding of LHON pathophysiology, providing an integrated paradigm for pathogenesis of mitochondrial diseases and druggable targets for therapy

Efficient mitochondrial biogenesis drives incomplete penetrance in Leber's hereditary optic neuropathy

Leber's hereditary optic neuropathy is a maternally inherited blinding disease caused as a result of homoplasmic point mutations in complex I subunit genes of mitochondrial DNA. It is characterized by incomplete penetrance, as only some mutation carriers become affected. Thus, the mitochondrial DNA mutation is necessary but not sufficient to cause optic neuropathy. Environmental triggers and genetic modifying factors have been considered to explain its variable penetrance. We measured the mitochondrial DNA copy number and mitochondrial mass indicators in blood cells from affected and carrier individuals, screening three large pedigrees and 39 independently collected smaller families with Leber's hereditary optic neuropathy, as well as muscle biopsies and cells isolated by laser capturing from post-mortem specimens of retina and optic nerves, the latter being the disease targets. We show that unaffected mutation carriers have a significantly higher mitochondrial DNA copy number and mitochondrial mass compared with their affected relatives and control individuals. Comparative studies of fibroblasts from affected, carriers and controls, under different paradigms of metabolic demand, show that carriers display the highest capacity for activating mitochondrial biogenesis. Therefore we postulate that the increased mitochondrial biogenesis in carriers may overcome some of the pathogenic effect of mitochondrial DNA mutations. Screening of a few selected genetic variants in candidate genes involved in mitochondrial biogenesis failed to reveal any significant association. Our study provides a valuable mechanism to explain variability of penetrance in Leber's hereditary optic neuropathy and clues for high throughput genetic screening to identify the nuclear modifying gene(s), opening an avenue to develop predictive genetic tests on disease risk and therapeutic strategies.TelethonAssociazione Serena Talarico per i giovani nel mondo and Fondazione Giuseppe Tomasello O.N.L.U.S.Mitocon OnlusResearch to Prevent BlindnessInternational Foundation for Optic Nerve Diseases (IFOND)Struggling Within Leber'sPoincenot FamilyEierman FoundationNational Eye InstituteUniv Rome, Dept Radiol Oncol & Pathol, Rome, ItalyUniv Bologna, Dept Biomed & NeuroMotor Sci DIBINEM, Bologna, ItalyUniv Bari, Dept Biosci Biotechnol & Biopharmaceut, Bari, ItalyBellaria Hosp, IRCCS Ist Sci Neurol Bologna, I-40139 Bologna, ItalyUSC, Keck Sch Med, Dept Ophthalmol, Los Angeles, CA USAUSC, Keck Sch Med, Dept Neurosurg, Los Angeles, CA USAUniv Trieste, Dept Reprod Sci Dev & Publ Hlth, Trieste, ItalyUniv Trieste, IRCCS Burlo Garofolo Children Hosp, Trieste, ItalyNewcastle Univ, Inst Med Genet, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, EnglandFdn Ist Neurol Carlo Besta IRCCS, Unit Mol Neurogenet, Milan, ItalyMRC Mitochondrial Biol Unit, Cambridge, EnglandFed Univ São Paulo UNIFESP, Dept Ophthalmol, São Paulo, BrazilUniv São Paulo, Inst Psychol, Dept Expt Psychol, São Paulo, BrazilStudio Oculist dAzeglio, Bologna, ItalyOsped San Giovanni Evangelista, Tivoli, ItalyAzienda Osped San Camillo Forlanini, Rome, ItalyUniv Rome, Dipartimento Metodi & Modelli Econ Finanza & Terr, Rome, ItalyUniv Rome, Dept Mol Med, Rome, ItalyFed Univ São Paulo UNIFESP, Dept Ophthalmol, São Paulo, BrazilTelethon: GGP06233Telethon: GGP11182Telethon: GPP10005National Eye Institute: EY03040Web of Scienc

Alterações dos potenciais visuais evocados nos olhos contralaterais de crianças com ambliopia estrabísmica e anisometrópica

Purpose: To evaluate visual acuity and transient pattern reversal (PR) visual evoked potentials (VEPs) in the fellow eyes of children with strabismic and/or anisometropic amblyopia. Methods: Children diagnosed with strabismic and/or anisometropic amblyopia were recruited for electrophysiological assessment by VEPs. Monocular grating and optotype acuity were measured using sweep-VEPs and an Early Treatment Diabetic Retinopathy Study chart, respectively. During the same visit, transient PR-VEPs of each eye were recorded using stimuli subtending with a visual angle of 60', 15', and 7.5'. Parameters of amplitude (in mu V) and latency (in ms) were determined from VEP recordings. Results: A group of 40 strabismic and/or anisometropic amblyopic children (22 females: 55%, mean age = 8.7 +/- 2.2 years, median = 8 years) was examined. A control group of 19 healthy children (13 females: 68.4%, mean age = 8.2 +/- 2.6 years, median = 8 years) was also included. The fellow eyes of all amblyopes had significantly worse optotype acuity (p = 0.021) than the control group, regardless of whether they were strabismic (p = 0.040) or anisometropic (p = 0.048). Overall, grating acuity was significantly worse in the fellow eyes of amblyopes (p = 0.016) than in healthy controls. Statistically prolonged latency for visual angles of 15' and 7.5' (p = 0.018 and 0.002, respectively) was found in the strabismic group when compared with the control group. For the smaller visual stimulus (7.5'), statistically prolonged latency was found among all fellow eyes of amblyopic children (p< 0.001). Conclusions: The fellow eyes of amblyopic children showed worse optotype and grating acuity, with subtle abnormalities in the PR-VEP detected as prolonged latencies for smaller size stimuli when compared with eyes of healthy children. These findings show the deleterious effects of amblyopia in several distinct visual functions, mainly those related to spatial vision.Univ Fed Sao Paulo UNIFESP, Dept Opththalmol & Visual Sci, EPM, Sao Paulo, SP, BrazilUniv Fed Sao Paulo UNIFESP, Dept Opththalmol & Visual Sci, EPM, Sao Paulo, SP, BrazilWeb of Scienc