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Holmquist D, Epstein D, Olsson M, Wissinger B, Kohl S, Hengstler J, Tear-Fahnehjelm K. Visual and ocular findings in a family with X-linked cone dysfunction and protanopia. Ophthalmic Genet 2021; 42:570-576. [PMID: 34287097 DOI: 10.1080/13816810.2021.1938139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Background: Bornholm eye disease (BED) is a rare X-linked cone dysfunction disorder with high myopia, amblyopia, and color vision defects.Materials and methods: Visual and ocular outcomes in a family where two of five siblings had molecularly confirmed BED are reported. Ophthalmological assessments included best-corrected visual acuity (BCVA), color vision test, and optical coherence tomography (OCT). Medical records, electroretinography (ERG), and genetic analyses were re-evaluated.Results: Two male siblings had confirmed BED with myopia and protanopia. The younger brother had high myopia, subnormal BCVA, and ocular fundi that showed tilted discs, crescent shaped peripapillary atrophy, and visible choroidal vessels. OCT confirmed retinal and choroidal atrophy. The older brother was lightly myopic with normal/subnormal BCVA and subtle findings in the fundi. Both brothers had abnormal ERG recordings with a decreased cone response. They also had a structurally intact OPN1LW/OPN1MW gene cluster. The OPN1LW gene was shown to carry a deleterious variant combination in exon 3 known to result in mis-splicing of opsin mRNA and acknowledged as LIAVA amino acid delineation (Leu153-Ile171-Ala174-Val178-Ala180), while the OPN1MW gene exon 3 showed a non-pathogenic variant combination (MVVVA). Another normal-sighted brother carried another wildtype variant combination (LVAIS) in exon 3 of the OPN1LW gene.Conclusions: The two affected brothers demonstrated a large variability in their phenotypes even though the genotypes were identical. They presented a disease-associated haplotype in exon 3 of OPN1LW that has been described as the molecular cause of BED.
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Weisschuh N, Schimpf-Linzenbold S, Mazzola P, Kieninger S, Xiao T, Kellner U, Neuhann T, Kelbsch C, Tonagel F, Wilhelm H, Kohl S, Wissinger B. Mutation spectrum of the OPA1 gene in a large cohort of patients with suspected dominant optic atrophy: Identification and classification of 48 novel variants. PLoS One 2021; 16:e0253987. [PMID: 34242285 PMCID: PMC8270428 DOI: 10.1371/journal.pone.0253987] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 06/17/2021] [Indexed: 12/18/2022] Open
Abstract
Autosomal dominant optic atrophy is one of the most common inherited optic neuropathies. This disease is genetically heterogeneous, but most cases are due to pathogenic variants in the OPA1 gene: depending on the population studied, 32–90% of cases harbor pathogenic variants in this gene. The aim of this study was to provide a comprehensive overview of the entire spectrum of likely pathogenic variants in the OPA1 gene in a large cohort of patients. Over a period of 20 years, 755 unrelated probands with a diagnosis of bilateral optic atrophy were referred to our laboratory for molecular genetic investigation. Genetic testing of the OPA1 gene was initially performed by a combined analysis using either single-strand conformation polymorphism or denaturing high performance liquid chromatography followed by Sanger sequencing to validate aberrant bands or melting profiles. The presence of copy number variations was assessed using multiplex ligation-dependent probe amplification. Since 2012, genetic testing was based on next-generation sequencing platforms. Genetic screening of the OPA1 gene revealed putatively pathogenic variants in 278 unrelated probands which represent 36.8% of the entire cohort. A total of 156 unique variants were identified, 78% of which can be considered null alleles. Variant c.2708_2711del/p.(V903Gfs*3) was found to constitute 14% of all disease-causing alleles. Special emphasis was placed on the validation of splice variants either by analyzing cDNA derived from patients´ blood samples or by heterologous splice assays using minigenes. Splicing analysis revealed different aberrant splicing events, including exon skipping, activation of exonic or intronic cryptic splice sites, and the inclusion of pseudoexons. Forty-eight variants that we identified were novel. Nine of them were classified as pathogenic, 34 as likely pathogenic and five as variant of uncertain significance. Our study adds a significant number of novel variants to the mutation spectrum of the OPA1 gene and will thereby facilitate genetic diagnostics of patients with suspected dominant optic atrophy.
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Lenaers G, Neutzner A, Le Dantec Y, Jüschke C, Xiao T, Decembrini S, Swirski S, Kieninger S, Agca C, Kim US, Reynier P, Yu-Wai-Man P, Neidhardt J, Wissinger B. Dominant optic atrophy: Culprit mitochondria in the optic nerve. Prog Retin Eye Res 2021; 83:100935. [PMID: 33340656 DOI: 10.1016/j.preteyeres.2020.100935] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 12/05/2020] [Accepted: 12/09/2020] [Indexed: 12/14/2022]
Abstract
Dominant optic atrophy (DOA) is an inherited mitochondrial disease leading to specific degeneration of retinal ganglion cells (RGCs), thus compromising transmission of visual information from the retina to the brain. Usually, DOA starts during childhood and evolves to poor vision or legal blindness, affecting the central vision, whilst sparing the peripheral visual field. In 20% of cases, DOA presents as syndromic disorder, with secondary symptoms affecting neuronal and muscular functions. Twenty years ago, we demonstrated that heterozygous mutations in OPA1 are the most frequent molecular cause of DOA. Since then, variants in additional genes, whose functions in many instances converge with those of OPA1, have been identified by next generation sequencing. OPA1 encodes a dynamin-related GTPase imported into mitochondria and located to the inner membrane and intermembrane space. The many OPA1 isoforms, resulting from alternative splicing of three exons, form complex homopolymers that structure mitochondrial cristae, and contribute to fusion of the outer membrane, thus shaping the whole mitochondrial network. Moreover, OPA1 is required for oxidative phosphorylation, maintenance of mitochondrial genome, calcium homeostasis and regulation of apoptosis, thus making OPA1 the Swiss army-knife of mitochondria. Understanding DOA pathophysiology requires the understanding of RGC peculiarities with respect to OPA1 functions. Besides the tremendous energy requirements of RGCs to relay visual information from the eye to the brain, these neurons present unique features related to their differential environments in the retina, and to the anatomical transition occurring at the lamina cribrosa, which parallel major adaptations of mitochondrial physiology and shape, in the pre- and post-laminar segments of the optic nerve. Three DOA mouse models, with different Opa1 mutations, have been generated to study intrinsic mechanisms responsible for RGC degeneration, and these have further revealed secondary symptoms related to mitochondrial dysfunctions, mirroring the more severe syndromic phenotypes seen in a subgroup of patients. Metabolomics analyses of cells, mouse organs and patient plasma mutated for OPA1 revealed new unexpected pathophysiological mechanisms related to mitochondrial dysfunction, and biomarkers correlated quantitatively to the severity of the disease. Here, we review and synthesize these data, and propose different approaches for embracing possible therapies to fulfil the unmet clinical needs of this disease, and provide hope to affected DOA patients.
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Kuehlewein L, Zobor D, Andreasson SO, Ayuso C, Banfi S, Bocquet B, Bernd AS, Biskup S, Boon CJF, Downes SM, Fischer MD, Holz FG, Kellner U, Leroy BP, Meunier I, Nasser F, Rosenberg T, Rudolph G, Stingl K, Thiadens AAHJ, Wilhelm B, Wissinger B, Zrenner E, Kohl S, Weisschuh N. Clinical Phenotype and Course of PDE6A-Associated Retinitis Pigmentosa Disease, Characterized in Preparation for a Gene Supplementation Trial. JAMA Ophthalmol 2021; 138:1241-1250. [PMID: 33057649 DOI: 10.1001/jamaophthalmol.2020.4206] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Importance Treatment trials require sound knowledge on the natural course of disease. Objective To assess clinical features, genetic findings, and genotype-phenotype correlations in patients with retinitis pigmentosa (RP) associated with biallelic sequence variations in the PDE6A gene in preparation for a gene supplementation trial. Design, Setting, and Participants This prospective, longitudinal, observational cohort study was conducted from January 2001 to December 2019 in a single center (Centre for Ophthalmology of the University of Tübingen, Germany) with patients recruited multinationally from 12 collaborating European tertiary referral centers. Patients with retinitis pigmentosa, sequence variants in PDE6A, and the ability to provide informed consent were included. Exposures Comprehensive ophthalmological examinations; validation of compound heterozygosity and biallelism by familial segregation analysis, allelic cloning, or assessment of next-generation sequencing-read data, where possible. Main Outcomes and Measures Genetic findings and clinical features describing the entire cohort and comparing patients harboring the 2 most common disease-causing variants in a homozygous state (c.304C>A;p.(R102S) and c.998 + 1G>A;p.?). Results Fifty-seven patients (32 female patients [56%]; mean [SD], 40 [14] years) from 44 families were included. All patients completed the study. Thirty patients were homozygous for disease-causing alleles. Twenty-seven patients were heterozygous for 2 different PDE6A variants each. The most frequently observed alleles were c.304C>A;p.(R102S), c.998 + 1G>A;p.?, and c.2053G>A;p.(V685M). The mean (SD) best-corrected visual acuity was 0.43 (0.48) logMAR (Snellen equivalent, 20/50). The median visual field area with object III4e was 660 square degrees (5th and 95th percentiles, 76 and 11 019 square degrees; 25th and 75th percentiles, 255 and 3923 square degrees). Dark-adapted and light-adapted full-field electroretinography showed no responses in 88 of 108 eyes (81.5%). Sixty-nine of 108 eyes (62.9%) showed additional findings on optical coherence tomography imaging (eg, cystoid macular edema or macular atrophy). The variant c.998 + 1G>A;p.? led to a more severe phenotype when compared with the variant c.304C>A;p.(R102S). Conclusions and Relevance Seventeen of the PDE6A variants found in these patients appeared to be novel. Regarding the clinical findings, disease was highly symmetrical between the right and left eyes and visual impairment was mild or moderate in 90% of patients, providing a window of opportunity for gene therapy.
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Boussaad I, Obermaier CD, Hanss Z, Bobbili DR, Bolognin S, Glaab E, Wołyńska K, Weisschuh N, De Conti L, May C, Giesert F, Grossmann D, Lambert A, Kirchen S, Biryukov M, Burbulla LF, Massart F, Bohler J, Cruciani G, Schmid B, Kurz-Drexler A, May P, Duga S, Klein C, Schwamborn JC, Marcus K, Woitalla D, Vogt Weisenhorn DM, Wurst W, Baralle M, Krainc D, Gasser T, Wissinger B, Krüger R. A patient-based model of RNA mis-splicing uncovers treatment targets in Parkinson's disease. Sci Transl Med 2021; 12:12/560/eaau3960. [PMID: 32908004 DOI: 10.1126/scitranslmed.aau3960] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 01/24/2020] [Accepted: 06/22/2020] [Indexed: 12/18/2022]
Abstract
Parkinson's disease (PD) is a heterogeneous neurodegenerative disorder with monogenic forms representing prototypes of the underlying molecular pathology and reproducing to variable degrees the sporadic forms of the disease. Using a patient-based in vitro model of PARK7-linked PD, we identified a U1-dependent splicing defect causing a drastic reduction in DJ-1 protein and, consequently, mitochondrial dysfunction. Targeting defective exon skipping with genetically engineered U1-snRNA recovered DJ-1 protein expression in neuronal precursor cells and differentiated neurons. After prioritization of candidate drugs, we identified and validated a combinatorial treatment with the small-molecule compounds rectifier of aberrant splicing (RECTAS) and phenylbutyric acid, which restored DJ-1 protein and mitochondrial dysfunction in patient-derived fibroblasts as well as dopaminergic neuronal cell loss in mutant midbrain organoids. Our analysis of a large number of exomes revealed that U1 splice-site mutations were enriched in sporadic PD patients. Therefore, our study suggests an alternative strategy to restore cellular abnormalities in in vitro models of PD and provides a proof of concept for neuroprotection based on precision medicine strategies in PD.
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Nassisi M, Smirnov VM, Solis Hernandez C, Mohand‐Saïd S, Condroyer C, Antonio A, Kühlewein L, Kempf M, Kohl S, Wissinger B, Nasser F, Ragi SD, Wang N, Sparrow JR, Greenstein VC, Michalakis S, Mahroo OA, Ba‐Abbad R, Michaelides M, Webster AR, Degli Esposti S, Saffren B, Capasso J, Levin A, Hauswirth WW, Dhaenens C, Defoort‐Dhellemmes S, Tsang SH, Zrenner E, Sahel J, Petersen‐Jones SM, Zeitz C, Audo I. CNGB1-related rod-cone dystrophy: A mutation review and update. Hum Mutat 2021; 42:641-666. [PMID: 33847019 PMCID: PMC8218941 DOI: 10.1002/humu.24205] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 03/26/2021] [Accepted: 04/08/2021] [Indexed: 12/29/2022]
Abstract
Cyclic nucleotide-gated channel β1 (CNGB1) encodes the 240-kDa β subunit of the rod photoreceptor cyclic nucleotide-gated ion channel. Disease-causing sequence variants in CNGB1 lead to autosomal recessive rod-cone dystrophy/retinitis pigmentosa (RP). We herein present a comprehensive review and analysis of all previously reported CNGB1 sequence variants, and add 22 novel variants, thereby enlarging the spectrum to 84 variants in total, including 24 missense variants (two of which may also affect splicing), 21 nonsense, 19 splicing defects (7 at noncanonical positions), 10 small deletions, 1 small insertion, 1 small insertion-deletion, 7 small duplications, and 1 gross deletion. According to the American College of Medical Genetics and Genomics classification criteria, 59 variants were considered pathogenic or likely pathogenic and 25 were variants of uncertain significance. In addition, we provide further phenotypic data from 34 CNGB1-related RP cases, which, overall, are in line with previous findings suggesting that this form of RP has long-term retention of useful central vision despite the early onset of night blindness, which is valuable for patient counseling, but also has implications for it being considered a priority target for gene therapy trials.
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Georgiou M, Robson AG, Fujinami K, Leo SM, Vincent A, Nasser F, Cabral De Guimarães TA, Khateb S, Pontikos N, Fujinami-Yokokawa Y, Liu X, Tsunoda K, Hayashi T, Vargas ME, Thiadens AAHJ, de Carvalho ER, Nguyen XTA, Arno G, Mahroo OA, Martin-Merida MI, Jimenez-Rolando B, Gordo G, Carreño E, Ayuso C, Sharon D, Kohl S, Huckfeldt RM, Wissinger B, Boon CJF, Banin E, Pennesi ME, Khan AO, Webster AR, Zrenner E, Héon E, Michaelides M. KCNV2-Associated Retinopathy: Genetics, Electrophysiology, and Clinical Course-KCNV2 Study Group Report 1. Am J Ophthalmol 2021; 225:95-107. [PMID: 33309813 PMCID: PMC8186730 DOI: 10.1016/j.ajo.2020.11.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 11/18/2020] [Accepted: 11/25/2020] [Indexed: 12/01/2022]
Abstract
PURPOSE To investigate genetics, electrophysiology, and clinical course of KCNV2-associated retinopathy in a cohort of children and adults. STUDY DESIGN This was a multicenter international clinical cohort study. METHODS Review of clinical notes and molecular genetic testing. Full-field electroretinography (ERG) recordings, incorporating the international standards, were reviewed and quantified and compared with age and recordings from control subjects. RESULTS In total, 230 disease-associated alleles were identified from 117 patients, corresponding to 75 different KCNV2 variants, with 28 being novel. The mean age of onset was 3.9 years old. All patients were symptomatic before 12 years of age (range, 0-11 years). Decreased visual acuity was present in all patients, and 4 other symptoms were common: reduced color vision (78.6%), photophobia (53.5%), nyctalopia (43.6%), and nystagmus (38.6%). After a mean follow-up of 8.4 years, the mean best-corrected visual acuity (BCVA ± SD) decreased from 0.81 ± 0.27 to 0.90 ± 0.31 logarithm of minimal angle of resolution. Full-field ERGs showed pathognomonic waveform features. Quantitative assessment revealed a wide range of ERG amplitudes and peak times, with a mean rate of age-associated reduction indistinguishable from the control group. Mean amplitude reductions for the dark-adapted 0.01 ERG, dark-adapted 10 ERG a-wave, and LA 3.0 30 Hz and LA3 ERG b-waves were 55%, 21%, 48%, and 74%, respectively compared with control values. Peak times showed stability across 6 decades. CONCLUSION In KCNV2-associated retinopathy, full-field ERGs are diagnostic and consistent with largely stable peripheral retinal dysfunction. Report 1 highlights the severity of the clinical phenotype and established a large cohort of patients, emphasizing the unmet need for trials of novel therapeutics.
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Kohl S, Llavona P, Sauer A, Reuter P, Weisschuh N, Kempf M, Dehmelt FA, Arrenberg AB, Sliesoraityte I, Zrenner E, van Schooneveld MJ, Rudolph G, Kühlewein L, Wissinger B. A duplication on chromosome 16q12 affecting the IRXB gene cluster is associated with autosomal dominant cone dystrophy with early tritanopic color vision defect. Hum Mol Genet 2021; 30:1218-1229. [PMID: 33891002 PMCID: PMC8212766 DOI: 10.1093/hmg/ddab117] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 04/15/2021] [Accepted: 04/15/2021] [Indexed: 02/06/2023] Open
Abstract
Cone dystrophies are a rare subgroup of inherited retinal dystrophies and hallmarked by color vision defects, low or decreasing visual acuity and central vision loss, nystagmus and photophobia. Applying genome-wide linkage analysis and array comparative genome hybridization, we identified a locus for autosomal dominant cone dystrophy on chromosome 16q12 in four independent multigeneration families. The locus is defined by duplications of variable size with a smallest region of overlap of 608 kb affecting the IRXB gene cluster and encompasses the genes IRX5 and IRX6. IRX5 and IRX6 belong to the Iroquois (Iro) protein family of homeodomain-containing transcription factors involved in patterning and regionalization of embryonic tissue in vertebrates, including the eye and the retina. All patients presented with a unique progressive cone dystrophy phenotype hallmarked by early tritanopic color vision defects. We propose that the disease underlies a misregulation of the IRXB gene cluster on chromosome 16q12 and demonstrate that overexpression of Irx5a and Irx6a, the two orthologous genes in zebrafish, results in visual impairment in 5-day-old zebrafish larvae.
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Täger J, Wissinger B, Kohl S, Reuter P. Identification of Chemical and Pharmacological Chaperones for Correction of Trafficking-Deficient Mutant Cyclic Nucleotide-Gated A3 Channels. Mol Pharmacol 2021; 99:460-468. [PMID: 33827965 DOI: 10.1124/molpharm.120.000180] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 03/30/2021] [Indexed: 12/19/2022] Open
Abstract
Trafficking deficiency caused by missense mutations is a well known phenomenon that occurs for mutant, misfolded proteins. Typically, the misfolded protein is retained by the protein quality-control system and degraded by the endoplasmic reticulum-associated protein degradation pathway and thus does not reach its destination, although residual function of the protein may be preserved. Chemical and pharmacological chaperones can improve the targeting of trafficking-deficient proteins and thus may be promising candidates for therapeutic applications. Here, we report the application of a cellular bioassay based on the bioluminescent calcium reporter aequorin to quantify surface expression of mutant CNGA3 channels associated with the autosomal recessively inherited retinal disease achromatopsia. A screening of 77 compounds enabled the identification of effective chemical and pharmacological chaperones that result in a 1.5- to 4.8-fold increase of surface expression of mutant CNGA3. Using selected compounds, we confirmed that the rescue of the defective trafficking is not limited to a single mutation in CNGA3. Active compounds and our structure-activity correlated data for the dihydropyridine compound class may provide valuable information for developing a treatment of the trafficking defect in achromatopsia. SIGNIFICANCE STATEMENT: This study describes a novel luminescence-based assay to detect the surface expression of mutant trafficking-deficient CNGA3 channels based on the calcium-sensitive photoprotein aequorin. Using this assay for a compound screening, this study identifies novel chemical and pharmacological chaperones that restore the surface localization of mutant trafficking-deficient CNGA3 channels. The results from this work may serve as starting point for the development of potent compounds that rescue trafficking deficiencies in the autosomal recessively inherited retinal disease achromatopsia.
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Stingl K, Kempf M, Bartz-Schmidt KU, Dimopoulos S, Reichel F, Jung R, Kelbsch C, Kohl S, Kortüm FC, Nasser F, Peters T, Wilhelm B, Wissinger B, Wozar F, Zrenner E, Fischer MD, Stingl K. Spatial and temporal resolution of the photoreceptors rescue dynamics after treatment with voretigene neparvovec. Br J Ophthalmol 2021; 106:831-838. [PMID: 33472769 PMCID: PMC9132865 DOI: 10.1136/bjophthalmol-2020-318286] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/22/2020] [Accepted: 12/28/2020] [Indexed: 12/21/2022]
Abstract
Background Voretigene neparvovec is a gene therapeutic agent for treatment of retinal dystrophies caused by bi-allelic RPE65 mutations. In this study, we report on a novel and objective evaluation of a retinotopic photoreceptor rescue. Methods Seven eyes of five patients (14, 21, 23, 24, 36 years, 1 male, 4 females) with bi-allelic RPE65 mutations have been treated with voretigene neparvovec. The clinical examinations included visual acuity testing, dark-adapted full-field stimulus threshold (FST), dark-adapted chromatic perimeter (DAC) with a 30-degree grid, and a 30 degrees grid scotopic and photopic chromatic pupil campimetry (CPC). All evaluations and spectral domain optical coherence tomography were performed at baseline, 1 month and 3 months. Results All except the oldest patient had a measurable improvement of the rod function assessed via FST, DAC or scotopic CPC at 1 month. The visual acuity improved slightly or remained stable in all eyes. A cone function improvement as measured by photopic CPC was observed in three eyes. The gain of the dark-adapted threshold with blue FST and the DAC stimuli (cyan) average correlated strongly with age (R2>0.7). The pupil response improvement in the scotopic CPC correlated with the baseline local retinal volume (R2=0.5). Conclusions The presented protocols allow evaluating the individual spatial and temporal effects of gene therapy effects. Additionally, we explored parameters that correlated with the success of the therapy. CPC and DAC present new and fast ways to assess functional changes in retinotopic maps of rod and cone function, measuring complementary aspects of retinal function.
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Fischer MD, Michalakis S, Wilhelm B, Zobor D, Muehlfriedel R, Kohl S, Weisschuh N, Ochakovski GA, Klein R, Schoen C, Sothilingam V, Garcia-Garrido M, Kuehlewein L, Kahle N, Werner A, Dauletbekov D, Paquet-Durand F, Tsang S, Martus P, Peters T, Seeliger M, Bartz-Schmidt KU, Ueffing M, Zrenner E, Biel M, Wissinger B. Safety and Vision Outcomes of Subretinal Gene Therapy Targeting Cone Photoreceptors in Achromatopsia: A Nonrandomized Controlled Trial. JAMA Ophthalmol 2021; 138:643-651. [PMID: 32352493 PMCID: PMC7193523 DOI: 10.1001/jamaophthalmol.2020.1032] [Citation(s) in RCA: 92] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Question What are the safety and vision outcomes associated with gene therapy for achromatopsia? Findings In this nonrandomized controlled trial of 9 patients with confirmed CNGA3-linked achromatopsia, gene therapy applying an adeno-associated viral vector encoding CNGA3, was not associated with substantial safety concerns and was associated with improvements of vision in patients. Meaning This study provides clinical proof of concept for viral vector–mediated gene supplementation therapy of inherited day blindness caused by pathogenic variants in the cone photoreceptor-specific gene CNGA3. Importance Achromatopsia linked to variations in the CNGA3 gene is associated with day blindness, poor visual acuity, photophobia, and involuntary eye movements owing to lack of cone photoreceptor function. No treatment is currently available. Objective To assess safety and vision outcomes of supplemental gene therapy with adeno-associated virus (AAV) encoding CNGA3 (AAV8.CNGA3) in patients with CNGA3-linked achromatopsia. Design, Setting, and Participants This open-label, exploratory nonrandomized controlled trial tested safety and vision outcomes of gene therapy vector AAV8.CNGA3 administered by subretinal injection at a single center. Nine patients (3 per dose group) with a clinical diagnosis of achromatopsia and confirmed biallelic disease-linked variants in CNGA3 were enrolled between November 5, 2015, and September 22, 2016. Data analysis was performed from June 6, 2017, to March 12, 2018. Intervention Patients received a single unilateral injection of 1.0 × 1010, 5.0 × 1010, or 1.0 × 1011 total vector genomes of AAV8.CNGA3 and were followed up for a period of 12 months (November 11, 2015, to October 10, 2017). Main Outcomes and Measures Safety as the primary end point was assessed by clinical examination of ocular inflammation. Systemic safety was assessed by vital signs, routine clinical chemistry testing, and full and differential blood cell counts. Secondary outcomes were change in visual function from baseline in terms of spatial and temporal resolution and chromatic, luminance, and contrast sensitivity throughout a period of 12 months after treatment. Results Nine patients (mean [SD] age, 39.6 [11.9] years; age range, 24-59 years; 8 [89%] male) were included in the study. Baseline visual acuity letter score (approximate Snellen equivalent) ranged from 34 (20/200) to 49 (20/100), whereas baseline contrast sensitivity log scores ranged from 0.1 to 0.9. All 9 patients underwent surgery and subretinal injection of AAV8.CNGA3 without complications. No substantial safety problems were observed during the 12-month follow-up period. Despite the congenital deprivation of cone photoreceptor–mediated vision in achromatopsia, all 9 treated eyes demonstrated some level of improvement in secondary end points regarding cone function, including mean change in visual acuity of 2.9 letters (95% CI, 1.65-4.13; P = .006, 2-sided t test paired samples). Contrast sensitivity improved by a mean of 0.33 log (95% CI, 0.14-0.51 log; P = .003, 2-sided t test paired samples). Conclusions and Relevance Subretinal gene therapy with AAV8.CNGA3 was not associated with substantial safety problems and was associated with cone photoreceptor activation in adult patients, as reflected by visual acuity and contrast sensitivity gains. Trial Registration ClinicalTrials.gov Identifier: NCT02610582
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Kortüm F, Kieninger S, Mazzola P, Kohl S, Wissinger B, Prokisch H, Stingl K, Weisschuh N. X-Linked Retinitis Pigmentosa Caused by Non-Canonical Splice Site Variants in RPGR. Int J Mol Sci 2021; 22:ijms22020850. [PMID: 33467000 PMCID: PMC7830253 DOI: 10.3390/ijms22020850] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/14/2021] [Accepted: 01/14/2021] [Indexed: 01/13/2023] Open
Abstract
We aimed to validate the effect of non-canonical splice site variants in the RPGR gene in five patients from four families diagnosed with retinitis pigmentosa. Four variants located in intron 2 (c.154 + 3_154 + 6del), intron 3 (c.247 + 5G>A), intron 7 (c.779-5T>G), and intron 13 (c.1573-12A>G), respectively, were analyzed by means of in vitro splice assays. Splicing analysis revealed different aberrant splicing events, including exon skipping and intronic nucleotide addition, which are predicted to lead either to an in-frame deletion affecting relevant protein domains or to a frameshift of the open reading frame. Our data expand the landscape of pathogenic variants in RPGR, thereby increasing the genetic diagnostic rate in retinitis pigmentosa and allowing patients harboring the analyzed variants to be enrolled in clinical trials.
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Charif M, Gueguen N, Ferré M, Elkarhat Z, Khiati S, LeMao M, Chevrollier A, Desquiret-Dumas V, Goudenège D, Bris C, Kane S, Alban J, Chupin S, Wetterwald C, Caporali L, Tagliavini F, LaMorgia C, Carbonelli M, Jurkute N, Barakat A, Gohier P, Verny C, Barth M, Procaccio V, Bonneau D, Zanlonghi X, Meunier I, Weisschuh N, Schimpf-Linzenbold S, Tonagel F, Kellner U, Yu-Wai-Man P, Carelli V, Wissinger B, Amati-Bonneau P, Reynier P, Lenaers G. Dominant ACO2 mutations are a frequent cause of isolated optic atrophy. Brain Commun 2021; 3:fcab063. [PMID: 34056600 PMCID: PMC8152918 DOI: 10.1093/braincomms/fcab063] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/11/2021] [Accepted: 02/12/2021] [Indexed: 12/24/2022] Open
Abstract
Biallelic mutations in ACO2, encoding the mitochondrial aconitase 2, have been identified in individuals with neurodegenerative syndromes, including infantile cerebellar retinal degeneration and recessive optic neuropathies (locus OPA9). By screening European cohorts of individuals with genetically unsolved inherited optic neuropathies, we identified 61 cases harbouring variants in ACO2, among whom 50 carried dominant mutations, emphasizing for the first time the important contribution of ACO2 monoallelic pathogenic variants to dominant optic atrophy. Analysis of the ophthalmological and clinical data revealed that recessive cases are affected more severely than dominant cases, while not significantly earlier. In addition, 27% of the recessive cases and 11% of the dominant cases manifested with extraocular features in addition to optic atrophy. In silico analyses of ACO2 variants predicted their deleterious impacts on ACO2 biophysical properties. Skin derived fibroblasts from patients harbouring dominant and recessive ACO2 mutations revealed a reduction of ACO2 abundance and enzymatic activity, and the impairment of the mitochondrial respiration using citrate and pyruvate as substrates, while the addition of other Krebs cycle intermediates restored a normal respiration, suggesting a possible short-cut adaptation of the tricarboxylic citric acid cycle. Analysis of the mitochondrial genome abundance disclosed a significant reduction of the mitochondrial DNA amount in all ACO2 fibroblasts. Overall, our data position ACO2 as the third most frequently mutated gene in autosomal inherited optic neuropathies, after OPA1 and WFS1, and emphasize the crucial involvement of the first steps of the Krebs cycle in the maintenance and survival of retinal ganglion cells.
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Weisschuh N, Mazzola P, Heinrich T, Haack T, Wissinger B, Tonagel F, Kelbsch C. First submicroscopic inversion of the OPA1 gene identified in dominant optic atrophy - a case report. BMC MEDICAL GENETICS 2020; 21:236. [PMID: 33243194 PMCID: PMC7690134 DOI: 10.1186/s12881-020-01166-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 11/10/2020] [Indexed: 12/16/2022]
Abstract
Background Dominant optic atrophy (DOA) is an inherited optic neuropathy that mainly affects visual acuity, central visual fields and color vision due to a progressive loss of retinal ganglion cells and their axons that form the optic nerve. Approximately 45–90% of affected individuals with DOA harbor pathogenic variants in the OPA1 gene. The mutation spectrum of OPA1 comprises nonsense, canonical and non-canonical splice site, frameshift and missense as well as copy number variants, but intragenic inversions have not been reported so far. Case presentation We report a 33-year-old male with characteristic clinical features of DOA. Whole-genome sequencing identified a structural variant of 2.4 kb comprising an inversion of 937 bp at the OPA1 locus. Fine mapping of the breakpoints to single nucleotide level revealed that the structural variation was an inversion flanked by two deletions. As this rearrangement inverts the entire first exon of OPA1, it was classified as likely pathogenic. Conclusions We report the first DOA case harboring an inversion in the OPA1 gene. Our study demonstrates that copy-neutral genomic rearrangements have to be considered as a possible cause of disease in DOA cases. Supplementary Information The online version contains supplementary material available at 10.1186/s12881-020-01166-z.
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Borovok N, Weiss C, Sharkia R, Reichenstein M, Wissinger B, Azem A, Mahajnah M. Gene and Protein Expression in Subjects With a Nystagmus-Associated AHR Mutation. Front Genet 2020; 11:582796. [PMID: 33193710 PMCID: PMC7542227 DOI: 10.3389/fgene.2020.582796] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 09/02/2020] [Indexed: 11/24/2022] Open
Abstract
Recently, a consanguineous family was identified in Israel with three children affected by Infantile Nystagmus and Foveal Hypoplasia, following an autosomal recessive mode of inheritance. A homozygous stop mutation c.1861C > T; p.Q621∗ in the aryl hydrocarbon receptor (AHR) gene (AHR; MIM 600253) was identified that co-segregated with the disease in the larger family. AHR is the first gene to be identified causing an autosomal recessive Infantile Nystagmus-related disease in humans. The goal of this study is to delineate the molecular basis of this newly discovered human genetic disorder associated with a rare AHR gene mutation. The gene and protein expression levels of AHR and selected AHR targets from leukocyte cultures of healthy subjects and the patients were analyzed. We observed significant variation between mRNA and protein expression of CYP1A1, CYP1B1, and TiPARP under rest and AHR-induced conditions. The CYP1A1 enzymatic activity in induced leukocytes also differs significantly between the patients and healthy volunteers. Intriguingly, the heterozygous subjects demonstrate CYP1A1 and TiPARP gene and protein expression similar to homozygous patients. In contrast, CYP1B1 inducibility and expression vary between hetero- and homozygous subjects. Similarity and differences in gene and protein expression between heterozygotes and homozygous patients can give us a hint as to which metabolic pathway/s might be involved in the Nystagmus etiology. Thus, we have a unique human model for AHR deficiency that will allow us the opportunity to study the biochemical basis of this rare human mutation, as well as the involvement of AHR in other physiological processes.
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Simcoe MJ, Weisschuh N, Wissinger B, Hysi PG, Hammond CJ. Genetic Heritability of Pigmentary Glaucoma and Associations With Other Eye Phenotypes. JAMA Ophthalmol 2020; 138:294-299. [PMID: 31999318 DOI: 10.1001/jamaophthalmol.2019.5961] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Importance Mechanisms behind pigmentary glaucoma, a form of early-onset glaucoma that may potentially lead to severe visual impairment or blindness, are poorly understood. Objective To calculate the single-nucleotide polymorphism (SNP) heritability of pigmentary glaucoma and identify genetic associations with the disease. Design, Setting and Participants This genome-wide association study included affected individuals from Germany and control participants from the United Kingdom. Genome-wide information was obtained for patients with pigmentary glaucoma and control participants free of glaucoma by using the Illumina Human Omni Express Exome 8v1-2 chip and genomic imputation. The SNP heritability of pigmentary glaucoma was estimated through a restricted maximum likelihood analysis. Associations between the genetic variants and pigmentary glaucoma obtained from age, sex, and principal component-adjusted logistic regression models were compared with those of SNPs previously associated with other eye phenotypes using Pearson product-moment correlations. Data were collected from November 2008 to January 2018, and analysis was completed between April 2018 and August 2019. Main Outcomes and Measures An estimate of SNP-explained heritability for pigmentary glaucoma; correlations of effect sizes between pigmentary glaucoma and iris pigmentation and myopia; and correlations of effect sizes between pigmentary glaucoma and other eye phenotypes. Results A total of 227 affected individuals (mean [SD] age, 58.7 [13.3] years) and 291 control participants (mean [SD] age, 80.2 [4.9] years) were included; all were of European ancestry. The SNP heritability of pigmentary glaucoma was 0.45 (SE, 0.22; P = 6.15 × 10-10). Twelve SNPs previously reported with genome-wide significant associations with eye pigmentation were associated with pigmentary glaucoma's SNP heritability (4.9% SNP heritability; 0.022; P = 6.0 × 10-4). Pigmentary glaucoma SNP effect sizes were correlated moderately for myopia (r, 0.42 [95% CI, 0.14-0.63]; P = 4.3 × 10-3) and more strongly with those for iris pigmentation (r = -0.69 [95% CI, -0.91 to -0.20]; P = .01), although this was nonsignificant per a strict adjusted significance threshold (P < .01). Conclusions and Relevance These findings support the conclusion that pigmentary glaucoma may have a genetic basis and be highly heritable. Variants associated with lighter eye color and myopia appear to be associated with increased risk of pigmentary glaucoma, but no shared genetic basis with primary open-angle glaucoma (or its quantitative endophenotype of cup-disc ratio) was observed.
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Sumaroka A, Cideciyan AV, Sheplock R, Wu V, Kohl S, Wissinger B, Jacobson SG. Foveal Therapy in Blue Cone Monochromacy: Predictions of Visual Potential From Artificial Intelligence. Front Neurosci 2020; 14:800. [PMID: 32848570 PMCID: PMC7416698 DOI: 10.3389/fnins.2020.00800] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 07/07/2020] [Indexed: 11/13/2022] Open
Abstract
Novel therapeutic approaches for treating inherited retinal degenerations (IRDs) prompt a need to understand which patients with impaired vision have the anatomical potential to gain from participation in a clinical trial. We used supervised machine learning to predict foveal function from foveal structure in blue cone monochromacy (BCM), an X-linked congenital cone photoreceptor dysfunction secondary to mutations in the OPN1LW/OPN1MW gene cluster. BCM patients with either disease-associated large deletion or missense mutations were studied and results compared with those from subjects with other forms of IRD and various degrees of preserved central structure and function. A machine learning technique was used to associate foveal sensitivities and best-corrected visual acuities to foveal structure in IRD patients. Two random forest (RF) models trained on IRD data were applied to predict foveal function in BCM. A curve fitting method was also used and results compared with those of the RF models. The BCM and IRD patients had a comparable range of foveal structure. IRD patients had peak sensitivity at the fovea. Machine learning could successfully predict foveal sensitivity (FS) results from segmented or un-segmented optical coherence tomography (OCT) input. Application of machine learning predictions to BCM at the fovea showed differences between predicted and measured sensitivities, thereby defining treatment potential. The curve fitting method provided similar results. Given a measure of visual acuity (VA) and foveal outer nuclear layer thickness, the question of how many lines of acuity would represent the best efficacious result for each BCM patient could be answered. We propose that foveal vision improvement potential in BCM is predictable from retinal structure using machine learning and curve fitting approaches. This should allow estimates of maximal efficacy in patients being considered for clinical trials and also guide decisions about dosing.
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Piro-Mégy C, Sarzi E, Tarrés-Solé A, Péquignot M, Hensen F, Quilès M, Manes G, Chakraborty A, Sénéchal A, Bocquet B, Cazevieille C, Roubertie A, Müller A, Charif M, Goudenège D, Lenaers G, Wilhelm H, Kellner U, Weisschuh N, Wissinger B, Zanlonghi X, Hamel C, Spelbrink JN, Sola M, Delettre C. Dominant mutations in mtDNA maintenance gene SSBP1 cause optic atrophy and foveopathy. J Clin Invest 2020; 130:143-156. [PMID: 31550237 PMCID: PMC6934222 DOI: 10.1172/jci128513] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 09/19/2019] [Indexed: 01/20/2023] Open
Abstract
Mutations in genes encoding components of the mitochondrial DNA (mtDNA) replication machinery cause mtDNA depletion syndromes (MDSs), which associate ocular features with severe neurological syndromes. Here, we identified heterozygous missense mutations in single-strand binding protein 1 (SSBP1) in 5 unrelated families, leading to the R38Q and R107Q amino acid changes in the mitochondrial single-stranded DNA-binding protein, a crucial protein involved in mtDNA replication. All affected individuals presented optic atrophy, associated with foveopathy in half of the cases. To uncover the structural features underlying SSBP1 mutations, we determined a revised SSBP1 crystal structure. Structural analysis suggested that both mutations affect dimer interactions and presumably distort the DNA-binding region. Using patient fibroblasts, we validated that the R38Q variant destabilizes SSBP1 dimer/tetramer formation, affects mtDNA replication, and induces mtDNA depletion. Our study showing that mutations in SSBP1 cause a form of dominant optic atrophy frequently accompanied with foveopathy brings insights into mtDNA maintenance disorders.
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Weisschuh N, Obermaier CD, Battke F, Bernd A, Kuehlewein L, Nasser F, Zobor D, Zrenner E, Weber E, Wissinger B, Biskup S, Stingl K, Kohl S. Genetic architecture of inherited retinal degeneration in Germany: A large cohort study from a single diagnostic center over a 9-year period. Hum Mutat 2020; 41:1514-1527. [PMID: 32531858 DOI: 10.1002/humu.24064] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 02/27/2020] [Accepted: 05/04/2020] [Indexed: 12/29/2022]
Abstract
We aimed to unravel the molecular genetic basis of inherited retinal degeneration (IRD) in a comprehensive cohort of patients diagnosed in the largest center for IRD in Germany. A cohort of 2,158 affected patients from 1,785 families diagnosed with IRD was analyzed by targeted next-generation sequencing (NGS). Patients with single-gene disorders (i.e., choroideremia and retinoschisis) were analyzed by Sanger sequencing and multiplex ligation-dependent probe amplification. Our study cohort accounts for ∼7% of the estimated 30,000 patients with IRD in Germany, thereby providing representative data for both the prevalence of IRDs and the mutation spectrum of IRD genes for the population in Germany. We achieved a molecular diagnostic rate of 35-95%, depending on the clinical entities, with a high detection rate for achromatopsia, retinoschisis, and choroideremia, and a low detection rate for central areolar choroidal dystrophy and macular dystrophy. A total of 1,161 distinct variants were identified, including 501 novel variants, reaffirming the known vast genetic heterogeneity of IRD in a mainly outbred European population. This study demonstrates the clinical utility of panel-based NGS in a large and highly heterogeneous cohort from an outbred population and for the first time gives a comprehensive representation of the genetic landscape of IRDs in Germany. The data are valuable and crucial for the scientific community and healthcare providers, but also for the pharmaceutical industry in the progressing field of personalized medicine and gene therapy.
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Mayer AK, Mahajnah M, Thomas MG, Cohen Y, Habib A, Schulze M, Maconachie GDE, AlMoallem B, De Baere E, Lorenz B, Traboulsi EI, Kohl S, Azem A, Bauer P, Gottlob I, Sharkia R, Wissinger B. Homozygous stop mutation in AHR causes autosomal recessive foveal hypoplasia and infantile nystagmus. Brain 2020; 142:1528-1534. [PMID: 31009037 DOI: 10.1093/brain/awz098] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 02/04/2019] [Accepted: 02/16/2019] [Indexed: 01/27/2023] Open
Abstract
Herein we present a consanguineous family with three children affected by foveal hypoplasia with infantile nystagmus, following an autosomal recessive mode of inheritance. The patients showed normal electroretinography responses, no signs of albinism, and no anterior segment or brain abnormalities. Upon whole exome sequencing, we identified a homozygous mutation (c.1861C>T;p.Q621*) in the aryl hydrocarbon receptor (AHR) gene that perfectly co-segregated with the disease in the larger family. AHR is a ligand-activated transcription factor that has been intensively studied in xenobiotic-induced toxicity. Further, it has been shown to play a physiological role under normal cellular conditions, such as in immunity, inflammatory response and neurogenesis. Notably, knockout of the Ahr gene in mouse impairs optic nerve myelin sheath formation and results in oculomotor deficits sharing many features with our patients: the eye movement disorder in Ahr-/- mice appears early in development and presents as conjugate horizontal pendular nystagmus. We therefore propose AHR to be a novel disease gene for a new, recessively inherited disorder in humans, characterized by infantile nystagmus and foveal hypoplasia.
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Mayer AK, Balousha G, Sharkia R, Mahajnah M, Ayesh S, Schulze M, Buchert R, Zobor D, Azem A, Schöls L, Bauer P, Wissinger B. Unraveling the genetic cause of hereditary ophthalmic disorders in Arab societies from Israel and the Palestinian Authority. Eur J Hum Genet 2020; 28:742-753. [PMID: 31896775 DOI: 10.1038/s41431-019-0566-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 11/12/2019] [Accepted: 12/10/2019] [Indexed: 11/09/2022] Open
Abstract
Visual impairment due to inherited ophthalmic disorders is amongst the most common disabilities observed in populations practicing consanguineous marriages. Here we investigated the molecular genetic basis of an unselected broad range of ophthalmic disorders in 20 consanguineous families from Arab villages of Israel and the Palestinian Authority. Most patients had little or very poor prior clinical workup and were recruited in a field study. Homozygosity mapping followed by candidate gene sequencing applying conventional Sanger sequencing or targeted next generation sequencing was performed in six families. In the remaining 14 families, one affected subject per family was chosen for whole exome sequencing. We discovered likely disease-causing variants, all homozygous, in 19 of 20 independent families (95%) including a previously reported novel disease gene for congenital nystagmus associated with foveal hypoplasia. Moreover, we found a family in which disease-causing variants for two collagenopathies - Stickler and Knobloch syndrome - segregate within a large sibship. Nine of the 19 distinct variants observed in this study were novel. Our study demonstrated a very high molecular diagnostic yield for a highly diverse spectrum of rare ophthalmic disorders in Arab patients from Israel and the Palestinian Authority, even with very limited prior clinical investigation. We conclude that 'genetic testing first' may be an economic way to direct clinical care and to support proper genetic counseling and risk assessment in these families.
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Wissinger B. Non‐OPA1 genetic causes of dominant optic atrophies. Acta Ophthalmol 2019. [DOI: 10.1111/j.1755-3768.2019.8175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Weisschuh N, Sturm M, Baumann B, Audo I, Ayuso C, Bocquet B, Branham K, Brooks BP, Catalá-Mora J, Giorda R, Heckenlively JR, Hufnagel RB, Jacobson SG, Kellner U, Kitsiou-Tzeli S, Matet A, Martorell Sampol L, Meunier I, Rudolph G, Sharon D, Stingl K, Streubel B, Varsányi B, Wissinger B, Kohl S. Deep-intronic variants in CNGB3 cause achromatopsia by pseudoexon activation. Hum Mutat 2019; 41:255-264. [PMID: 31544997 DOI: 10.1002/humu.23920] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 08/20/2019] [Accepted: 09/16/2019] [Indexed: 01/18/2023]
Abstract
Our comprehensive cohort of 1100 unrelated achromatopsia (ACHM) patients comprises a considerable number of cases (~5%) harboring only a single pathogenic variant in the major ACHM gene CNGB3. We sequenced the entire CNGB3 locus in 33 of these patients to find a second variant which eventually explained the patients' phenotype. Forty-seven intronic CNGB3 variants were identified in 28 subjects after a filtering step based on frequency and the exclusion of variants found in cis with pathogenic alleles. In a second step, in silico prediction tools were used to filter out those variants with little odds of being deleterious. This left three variants that were analyzed using heterologous splicing assays. Variant c.1663-1205G>A, found in 14 subjects, and variant c.1663-2137C>T, found in two subjects, were indeed shown to exert a splicing defect by causing pseudoexon insertion into the transcript. Subsequent screening of further unsolved CNGB3 subjects identified four additional cases harboring the c.1663-1205G>A variant which makes it the eighth most frequent CNGB3 variant in our cohort. Compound heterozygosity could be validated in ten cases. Our study demonstrates that whole gene sequencing can be a powerful approach to identify the second pathogenic allele in patients apparently harboring only one disease-causing variant.
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Tobias P, Philipp SI, Stylianos M, Martin B, Barbara W, Felix R, Alexander OG, Eberhart Z, Marius U, Birgit K, Sven K, Ulrich BSK, Dominik FM, Bartz-Schmidt KU, Bolz S, Fischer D, Kohl S, Kühlewein L, Mühlfriedel R, Neubauer J, Ochakovski A, Paquet-Durand F, Seeliger M, Sothilingam V, Ueffing M, Weisschuh N, Wissinger B, Zhour A, Zobor D, Zrenner E, Biel M, Michalakis S, Schön C, Kahle N, Peters T, Wilhelm B, Tsang S, Glöckner CJ. Safety and Toxicology of Ocular Gene Therapy with Recombinant AAV Vector rAAV.hCNGA3 in Nonhuman Primates. HUM GENE THER CL DEV 2019; 30:50-56. [DOI: 10.1089/humc.2018.188] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Sumaroka A, Garafalo AV, Cideciyan AV, Charng J, Roman AJ, Choi W, Saxena S, Aksianiuk V, Kohl S, Wissinger B, Jacobson SG. Blue Cone Monochromacy Caused by the C203R Missense Mutation or Large Deletion Mutations. Invest Ophthalmol Vis Sci 2019; 59:5762-5772. [PMID: 30516820 DOI: 10.1167/iovs.18-25280] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To compare the phenotype of blue cone monochromacy (BCM) caused by large deletion mutations with those having the C203R missense mutation. Methods BCM patients with large deletion mutations (n = 21; age range, 5-60 years), and with the C203R missense mutation (n = 13; age range, 5-70 years), were studied with optical coherence tomography, visual acuity, and perimetric sensitivity in a retrospective observational case series. Perceptual estimates of spatial resolution driven by rods, S-cones, and L/M-cones were obtained by the choice of chromatic gratings presented on varied adapting conditions with a modified microperimeter. Results Both genotypes had abnormal foveal photoreceptor structure early in life. Patients with the C203R mutation, however, had decades-longer persistence of foveal photoreceptor outer nuclear layer thickness and a slower rate of development of inner segment/outer segment defects than did patients with large deletion mutations. At late ages, both genotypes had comparably severe losses of central structure. At the rod-rich hot spot, there was no difference in structure between cohorts with age. Grating acuities in all BCM patients were driven by S-cones and rods; the foveal structural differences were not reflected in a difference between cohorts in visual sensitivity and spatial resolution. Conclusions A difference in structural phenotype due to the C203R mutation versus large deletion mutations in BCM was detected as a more prolonged persistence of foveal photoreceptor structure in patients with the missense mutation. This should be taken into account in planning natural history studies, selecting outcomes for clinical trials, and defining the time window for possible therapies.
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