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Nilsson SEG. From basic to clinical research: a journey with the retina, the retinal pigment epithelium, the cornea, age-related macular degeneration and hereditary degenerations, as seen in the rear view mirror. ACTA ACUST UNITED AC 2006; 84:452-65; 451. [PMID: 16879565 DOI: 10.1111/j.1600-0420.2006.00751.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE This Acta Ophthalmologica Award and Gold Medal Honorary Lecture (the Lundsgaard Gold Medal Honorary Lecture) reviews some of the work I have carried out with my mentors and many of my wonderful collaborators and research students over more than 40 years, also including related work by other groups. It concentrates on the basic electrophysiology and ultrastructure of the retina and the retinal pigment epithelium (RPE), as well as covering basic and clinical aspects of the cornea, contact lenses, age-related macular degeneration (AMD) and hereditary diseases. METHODS The review describes research performed using light and electron microscopy, basic and clinical electrophysiology, genetics and biochemistry in animal experiments and in research on patients. It also outlines clinically used techniques, such as laser and photodynamic treatment and scanning laser ophthalmoscopy. RESULTS The paper reports on the following subjects: the mechanisms behind some of the electrical potentials originating in the retina and the RPE and the use of these potentials in hereditary diseases; corneal receptors for lectins and presumably for bacteria; the turnover of the photoreceptor outer segment and the formation of lipofuscin, including the relation of these processes to AMD; certain treatments for AMD, and hereditary degenerations in animal models, such as the RPE65 gene mutation in Briard dogs, which makes them a model of Leber's congenital amaurosis. The dogs are now treated successfully with gene therapy in the USA, and a clinical trial is in preparation. CONCLUSIONS During the last 40 years we have had the good fortune to experience a dramatic growth in knowledge and understanding within ophthalmic science of basic mechanisms. Huge progress has been made in diagnostics and clinical ophthalmological treatments, much to the benefit of our patients. Even a small contribution made by my group to these developments has been well worth the effort, particularly as scientific work is not just deeply satisfying: it is also fun!
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152
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Williams ML, Coleman JE, Haire SE, Aleman TS, Cideciyan AV, Sokal I, Palczewski K, Jacobson SG, Semple-Rowland SL. Lentiviral expression of retinal guanylate cyclase-1 (RetGC1) restores vision in an avian model of childhood blindness. PLoS Med 2006; 3:e201. [PMID: 16700630 PMCID: PMC1463903 DOI: 10.1371/journal.pmed.0030201] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Accepted: 02/23/2006] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Leber congenital amaurosis (LCA) is a genetically heterogeneous group of retinal diseases that cause congenital blindness in infants and children. Mutations in the GUCY2D gene that encodes retinal guanylate cyclase-1 (retGC1) were the first to be linked to this disease group (LCA type 1 [LCA1]) and account for 10%-20% of LCA cases. These mutations disrupt synthesis of cGMP in photoreceptor cells, a key second messenger required for function of these cells. The GUCY1*B chicken, which carries a null mutation in the retGC1 gene, is blind at hatching and serves as an animal model for the study of LCA1 pathology and potential treatments in humans. METHODS AND FINDINGS A lentivirus-based gene transfer vector carrying the GUCY2D gene was developed and injected into early-stage GUCY1*B embryos to determine if photoreceptor function and sight could be restored to these animals. Like human LCA1, the avian disease shows early-onset blindness, but there is a window of opportunity for intervention. In both diseases there is a period of photoreceptor cell dysfunction that precedes retinal degeneration. Of seven treated animals, six exhibited sight as evidenced by robust optokinetic and volitional visual behaviors. Electroretinographic responses, absent in untreated animals, were partially restored in treated animals. Morphological analyses indicated there was slowing of the retinal degeneration. CONCLUSIONS Blindness associated with loss of function of retGC1 in the GUCY1*B avian model of LCA1 can be reversed using viral vector-mediated gene transfer. Furthermore, this reversal can be achieved by restoring function to a relatively low percentage of retinal photoreceptors. These results represent a first step toward development of gene therapies for one of the more common forms of childhood blindness.
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Affiliation(s)
- Melissa L Williams
- 1Department of Neuroscience, University of Florida McKnight Brain Institute, Gainesville, Florida, United States of America
| | - Jason E Coleman
- 1Department of Neuroscience, University of Florida McKnight Brain Institute, Gainesville, Florida, United States of America
- 2Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Shannon E Haire
- 1Department of Neuroscience, University of Florida McKnight Brain Institute, Gainesville, Florida, United States of America
| | - Tomas S Aleman
- 3Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Artur V Cideciyan
- 3Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Izabel Sokal
- 4Department of Pathology, University of Washington, Seattle, Washington, United States of America
| | - Krzysztof Palczewski
- 5Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Samuel G Jacobson
- 3Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Susan L Semple-Rowland
- 1Department of Neuroscience, University of Florida McKnight Brain Institute, Gainesville, Florida, United States of America
- * To whom correspondence should be addressed. E-mail:
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153
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Stephen R, Palczewski K, Sousa MC. The crystal structure of GCAP3 suggests molecular mechanism of GCAP-linked cone dystrophies. J Mol Biol 2006; 359:266-75. [PMID: 16626734 PMCID: PMC4291230 DOI: 10.1016/j.jmb.2006.03.042] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Revised: 03/15/2006] [Accepted: 03/20/2006] [Indexed: 10/24/2022]
Abstract
Absorption of light by visual pigments initiates the phototransduction pathway that results in degradation of the intracellular pool of cyclic-GMP (cGMP). This hydrolysis promotes the closing of cGMP-gated cation channels and consequent hyperpolarization of rod and cone photoreceptor cell membranes. Guanylate cyclase-activating proteins (GCAPs) are a family of proteins that regulate retinal guanylate cyclase (GC) activity in a Ca2+-dependent manner. At high [Ca2+], typical of the dark-adapted state (approximately 500 nM), GCAPs inhibit retinal GCs. At the low [Ca2+] (approximately 50 nM) that occurs after the closing of cGMP-gated channels, GCAPs activate retinal GCs to replenish dark-state cGMP levels. Here, we report the crystal structure of unmyristoylated human GCAP3 with Ca2+ bound. GCAP3 is an EF-hand Ca2+-binding protein with Ca2+ bound to EF2, 3 and 4, while Ca2+ binding to EF-hand 1 is disabled. GCAP3 contains two domains with the EF-hand motifs arranged in a tandem array similar to GCAP2 and members of the recoverin subfamily of Ca2+-binding proteins. Residues not involved in Ca2+ binding, but conserved in all GCAPs, cluster around EF1 in the N-terminal domain and may represent the interface with GCs. Five point mutations in the closely related GCAP1 have been linked to the etiology of cone dystrophies. These residues are conserved in GCAP3 and the structure suggests important roles for these amino acids. We present a homology model of GCAP1 based on GCAP3 that offers insight into the molecular mechanism underlying the autosomal dominant cone dystrophies produced by GCAP1 mutations.
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Affiliation(s)
- Ricardo Stephen
- Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, CO 80309, USA
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154
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Abstract
For over 30 years, photoreceptors have been an outstanding model system for elucidating basic principles in sensory transduction and G protein signaling. Recently, photoreceptors have become an equally attractive model for studying many facets of neuronal cell biology. The primary goal of this review is to illustrate this rapidly growing trend. We will highlight the areas of active research in photoreceptor biology that reveal how different specialized compartments of the cell cooperate in fulfilling its overall function: converting photon absorption into changes in neurotransmitter release. The same trend brings us closer to understanding how defects in photoreceptor signaling can lead to cell death and retinal degeneration.
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Affiliation(s)
- Marie E Burns
- Center for Neuroscience and Department of Psychiatry and Behavioral Sciences, University of California, Davis, Davis, California 95616, USA.
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155
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Weleber RG, Gregory-Evans K. Retinitis Pigmentosa and Allied Disorders. Retina 2006. [DOI: 10.1016/b978-0-323-02598-0.50023-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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156
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Maubaret C, Hamel C. [Genetics of retinitis pigmentosa: metabolic classification and phenotype/genotype correlations]. J Fr Ophtalmol 2005; 28:71-92. [PMID: 15767903 DOI: 10.1016/s0181-5512(05)81029-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Retinitis pigmentosa (RP, prevalence 1/4000) is a set of hereditary retinal dystrophies characterized by pigment deposits in fundus and progressive death of photoreceptors, always associated with the alteration of retinal pigment epithelium. Genetic heterogeneity of the typical nonsyndromic form (rod cone dystrophy) is extensive: 11 genes and one locus were reported for autosomal dominant RP, 17 genes and five loci for autosomal recessive RP, and two genes and two loci for X-linked RP. A survey of mutation screening reports in large series of patients indicates that the frequency of mutations for all cloned genes varies from 40% to 54% of cases in autosomal dominant RP, from 17% to 24% in autosomal recessive RP (excluding the USH2A gene for which the values remain uncertain) and from 61% to 89% in X-linked RP. Very few studies report on sporadic cases except for the two X-linked genes, RP2 and RPGR, which account for 29% of sporadic cases in males. Altogether, the two most frequently involved genes are RPGR (13% of all RP cases) and RHO (4%), an important consideration for molecular diagnosis. Finally, we roughly estimate that currently known genes do not represent more than 50% of RP cases, suggesting that many genes remain to be discovered. The known genes can be classified into metabolic groups according to the encoded protein: visual transduction, visual cycle, transcription factors, structural proteins, spliceosome complex and cellular traffic, indicating the high level of specialization of photoreceptors and of the retinal pigment epithelium. In parallel with this classification, genotype/phenotype correlations have been established that will help ophthalmologists to suspect particular genes, and thereby mechanisms. This approach will provide better informations to patients and will orient the choice of future therapies.
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Affiliation(s)
- C Maubaret
- INSERM U583, Physiopathologie et Thérapie des Déficits Sensoriels et Moteurs, 34091 Montpellier cedex 05, 34090 Montpellier, France
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157
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Hanein S, Perrault I, Gerber S, Tanguy G, Hamel C, Dufier JL, Rozet JM, Kaplan J. [Leber congenital amaurosis: comprehensive survey of genetic heterogeneity. A clinical definition update]. J Fr Ophtalmol 2005; 28:98-105. [PMID: 15767905 DOI: 10.1016/s0181-5512(05)81031-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Leber congenital amaurosis (LCA) is the earliest and most severe form of all inherited retinal dystrophies, responsible for congenital blindness. Disease-associated mutations have been hitherto reported in seven genes. These genes are all expressed preferentially in the photoreceptor cells or the retinal pigment epithelium, but they are involved in strikingly different physiologic pathways, resulting in an unforeseeable pathophysiologic variety. This broad genetic and physiologic heterogeneity, which could greatly increase in the coming years, hinders molecular diagnosis in LCA patients. Genotyping is, however, required to establish genetically defined subgroups of patients ready for therapy. Here we report a comprehensive mutational analysis of all the known genes in 179 unrelated LCA patients, including 52 familial and 127 sporadic (27/127 consanguineous) cases. Mutations were identified in 47.5% of patients. GUCY2D accounted for by far the largest part of the LCA cases in our series (21.2%), followed by CRB1 (10%), RPE65 (6.1%), RPGRIP1 (4.5%), AIPL1 (3.4%), TULP1 (1.7%) and CRX (0.6%). The clinical history of all patients with mutations was carefully revisited in the search for phenotype variations. Genotype-phenotype correlations were found that made it possible to divide patients into two main groups. The first one includes patients whose symptoms fit the traditional definition of LCA, i.e., congenital or very early cone-rod dystrophy, while the second group gathers patients affected with severe yet progressive rod-cone dystrophy. In addition, objective ophthalmologic data subdivided each group into two subtypes. Based on these findings, we have drawn decisional flowcharts directing the molecular analysis of LCA genes in a given case. These flowcharts will hopefully lighten the onerous task of genotyping new patients, but only if the most precise clinical history since birth is available.
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Affiliation(s)
- S Hanein
- Unité de Recherche sur les Handicaps Génétiques de l'Enfant, INSERM U 393, Hôpital Necker-Enfants Malades, Paris, France
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158
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Galvin JA, Fishman GA, Stone EM, Koenekoop RK. EVALUATION OF GENOTYPE–PHENOTYPE ASSOCIATIONS IN LEBER CONGENITAL AMAUROSIS. Retina 2005; 25:919-29. [PMID: 16205573 DOI: 10.1097/00006982-200510000-00016] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To describe the clinical phenotypes associated with various genotypes known to cause Leber congenital amaurosis (LCA). METHODS One hundred ten LCA patients were screened for various probable disease-causing gene sequence variations. Those patients with a probable disease-causing sequence variation in one of six genotypes were recalled for a follow-up examination. Evaluations included assessment of visual acuity, slit-lamp biomicroscopy, and dilated fundus examination. When possible, Goldmann perimetry was also performed. RESULTS Of the 37 LCA patients with suspected disease-causing sequence variations, 7 had an AIPL1 variation, 8, a CRB1 variation, 2, a CRX variation, 4, a GUCY2D variation, 11, an RPE65 variation, and 5, an RPGRIP1 variation. Across the 6 genotypes, we observed a wide range of visual acuities from 20/40 to no light perception. The widest range of vision was noted for patients with a CRB1 or RPE65 variation. Younger patients with an AIPL1 or RPGRIP1 variation were found to have severely reduced vision. Drusenlike deposits were more selectively observed in patients with mutations in the AIPL1, CRB1, RPE65, and RPGRIP1 genes, whereas focal regions of peripheral chorioretinal atrophy were observed only in patients with AIPL1 or RPE65 variations. Neurologic, intellectual, or psychomotor developmental delay was noted in 8.1% of our cohort. CONCLUSIONS There was considerable overlap of phenotypic expression in six genetic subtypes in our LCA cohort. However, phenotypic trends were noted in our patients' visual acuities and posterior segment findings within genotypes. These findings have practical value for genetic screening strategies for LCA patients based upon phenotype as well as for counseling patients on their visual prognosis.
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Affiliation(s)
- Jennifer A Galvin
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois 60612, USA
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159
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Ozgül RK, Bozkurt B, Kiratli H, Oğüş A. Exclusion of LCA5 locus in a consanguineous Turkish family with macular coloboma-type LCA. Eye (Lond) 2005; 20:817-9. [PMID: 16082399 DOI: 10.1038/sj.eye.6702024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Leber's congenital amaurosis (LCA) is an inherited retinal dystrophy, which causes severe visual impairment in early childhood. Recent molecular genetic studies have linked 11 loci (AIPL1, CRB1, CRX, GUCY2D, RPE65, RDH12, RPGRIP1, TULP1, LCA3, LCA5, and LCA9) to LCA. LCA5 is a new locus, which maps to the 6q11-q16 chromosomal region and was found to be associated with macular coloboma-type LCA in a Pakistani family. Herein, we describe the molecular genetic features of a consanguineous Turkish family in which four children have macular coloboma-type LCA. METHODS Haplotype analysis was performed on the DNA of the family members using microsatellite markers against GUCY2D, RPE65, and LCA5. Genomic DNA was screened for mutations by means of single-strand conformational polymorphism (SSCP) analysis in exons of the RPE65 and CRX genes. RESULTS In haplotype analysis, no linkage to LCA5 or GUCY2D loci was detected. None of the tested markers showed homozygosity or segregation between affected siblings. PCR-SSCP mutation analysis revealed no mutations in the screened RPE65 and CRX genes. CONCLUSION We excluded LCA5 as the genetic cause of macular coloboma-type LCA in this Turkish family. Macular coloboma-type LCA shows genetic heterogeneity and it is not possible to establish a phenotype-genotype correlation with LCA5 and macular coloboma.
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Affiliation(s)
- R K Ozgül
- Department of Molecular Biology, Hacettepe University, Ankara, Turkey.
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160
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Lu X, Ferreira PA. Identification of novel murine- and human-specific RPGRIP1 splice variants with distinct expression profiles and subcellular localization. Invest Ophthalmol Vis Sci 2005; 46:1882-90. [PMID: 15914599 PMCID: PMC1769349 DOI: 10.1167/iovs.04-1286] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Mutations in RPGRIP1 cause Leber congenital amaurosis. The human and bovine RPGRIP1 undergo alternative splicing. A single murine rpgrip1 transcript has been reported, but distinct expression profiles of RPGRIP1 isoforms exist between species in the retina. To elucidate the heterogeneity of RPGRIP1 isoforms and the degree of functional redundancy among these, we extended the analysis of RPGRIP1 to the region between exons 12 and 14, which undergoes significant alternative splicing. METHODS Identification of alternative splice transcripts of murine and human RPGRIP1 was performed by reverse transcription-polymerase chain reaction (RT-PCR). The murine rpgrip1 isoforms were analyzed by immunoblot and immunocytochemistry analysis of murine retinas and transient transfected cultured cells. RESULTS A novel murine-specific transcript, rpgrip1b was identified. It arises from the extension of exon 13, leading to the premature truncation of rpgrip1 and deletion of its C2 and RID domains. It is predominantly expressed in the retina, where it is more abundant than the transcript(s) encompassing the constitutive exons 12 to 14. Conversely, the human retina lacks rpgrip1b, and the constitutive transcript is the major isoform. The subcellular distribution of rpgrip1b is distinct from its larger isoform, rpgrip1. In the photoreceptor inner segments and cells expressing enhanced green fluorescent protein (EGFP)-rpgrip1b, rpgrip1b is dispersed as punctate foci throughout the perikarya, where it colocalizes with a subpopulation of lysosomes. CONCLUSIONS These data support the RPGR-independent function of the isotype- and species-specific rpgrip1b in lysosome-related processes. The results further strengthen the model of the selective participation of distinct RPGRIP1 isoforms in different subcellular processes and molecular pathogenesis of RPGRIP1-allied diseases.
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Affiliation(s)
| | - Paulo A. Ferreira
- Corresponding author: Paulo A. Ferreira, Departments of Ophthalmology, and Molecular Genetics and Microbiology, Duke University Medical Center, Erwin Road, Durham, NC 27710;
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161
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Sokal I, Dupps WJ, Grassi MA, Brown J, Affatigato LM, Roychowdhury N, Yang L, Filipek S, Palczewski K, Stone EM, Baehr W. A novel GCAP1 missense mutation (L151F) in a large family with autosomal dominant cone-rod dystrophy (adCORD). Invest Ophthalmol Vis Sci 2005; 46:1124-32. [PMID: 15790869 PMCID: PMC1352313 DOI: 10.1167/iovs.04-1431] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To elucidate the phenotypic and biochemical characteristics of a novel mutation associated with autosomal dominant cone-rod dystrophy (adCORD). METHODS Twenty-three family members of a CORD pedigree underwent clinical examinations, including visual acuity tests, standardized full-field ERG, and fundus photography. Genomic DNA was screened for mutations in GCAP1 exons using DNA sequencing and single-strand conformational polymorphism (SSCP) analysis. Function and stability of recombinant GCAP1-L151F were tested as a function of [Ca(2+)], and its structure was probed by molecular dynamics. RESULTS Affected family members experienced dyschromatopsia, hemeralopia, and reduced visual acuity by the second to third decade of life. Electrophysiology revealed a nonrecordable photopic response with later attenuation of the scotopic response. Affected family members harbored a C-->T transition in exon 4 of the GCAP1 gene, resulting in an L151F missense mutation affecting the EF hand motif 4 (EF4). This change was absent in 11 unaffected family members and in 100 unrelated normal subjects. GCAP1-L151F stimulation of photoreceptor guanylate cyclase was not completely inhibited at high physiological [Ca(2+)], consistent with a lowered affinity for Ca(2+)-binding to EF4. CONCLUSIONS A novel L151F mutation in the EF4 hand domain of GCAP1 is associated with adCORD. The clinical phenotype is characterized by early cone dysfunction and a progressive loss of rod function. The biochemical phenotype is best described as persistent stimulation of photoreceptor guanylate cyclase, representing a gain of function of mutant GCAP1. Although a conservative substitution, molecular dynamics suggests a significant change in Ca(2+)-binding to EF4 and EF2 and changes in the shape of L151F-GCAP1.
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Affiliation(s)
| | | | | | - Jeremiah Brown
- Department of Ophthalmology and Visual Sciences, and the
| | | | | | - Lili Yang
- Departments of Ophthalmology and Visual Sciences
| | - Slawomir Filipek
- International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Krzysztof Palczewski
- From the Departments of Ophthalmology
- Pharmacology, and
- Chemistry, University of Washington, Seattle, Washington; the
| | - Edwin M. Stone
- Department of Ophthalmology and Visual Sciences, and the
- Howard Hughes Medical Institute, University of Iowa Carver College of Medicine, Iowa City, Iowa; the
| | - Wolfgang Baehr
- Departments of Ophthalmology and Visual Sciences
- Biology, and
- Neurobiology and Anatomy, University of Utah, Salt Lake City, Utah; and the
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162
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Fazzi E, Signorini SG, Uggetti C, Bianchi PE, Lanners J, Lanzi G. Towards improved clinical characterization of Leber congenital amaurosis: neurological and systemic findings. Am J Med Genet A 2005; 132A:13-9. [PMID: 15580639 DOI: 10.1002/ajmg.a.30301] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Leber congenital amaurosis (LCA) is the most severe form of inherited retinal dystrophy that presents in infancy. LCA is both clinically and genetically heterogeneous. The aim of our study was to clarify the clinical aspects of LCA and to contribute to improved characterization of the disorder. We studied 40 children affected by LCA (mean age at first observation: 19 months, range: 8-50 months), who underwent a comprehensive evaluation that included: neurophthalmological evaluation, electroretinogram (ERG), and visual evoked potentials (VEPs), general and neurological examinations, developmental assessment using scales for visually impaired children, neuroradiological examinations, hepatic and renal function and metabolic investigations, brainstem auditory evoked potentials (BAEPs), EEG, and hand radiographs. Analyses of known LCA genes are ongoing. The subjects are still being followed up at 6-/12-month intervals. All the subjects fulfilled De Laey's criteria for LCA. The neurological examination was abnormal in 31 cases (hypotonia, ataxia with/without associated cerebellar signs). Cognitive development was normal in 24 cases, borderline in five, and subnormal in 11. Mild and nonspecific alterations on MRI were present in seven cases, and "molar tooth" sign in four; all the others had a normal neuroradiological picture. Among the subjects presenting with neurological signs, a subgroup (13 patients) emerged that was characterized by systemic (skin, kidney, liver) involvement. Our data confirm that LCA is a heterogeneous entity that can present as an isolated ocular manifestation, or in association with neurological and systemic abnormalities and support the need for a multidisciplinary approach to this entity and for genotype-phenotype studies.
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Affiliation(s)
- Elisa Fazzi
- Department of Child Neurology and Psychiatry, IRCCS C. Mondino Institute of Neurology, University of Pavia, Pavia, Italy.
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163
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Galvin JA, Fishman GA, Stone EM, Koenekoop RK. Clinical phenotypes in carriers of Leber congenital amaurosis mutations. Ophthalmology 2005; 112:349-56. [PMID: 15691574 DOI: 10.1016/j.ophtha.2004.08.023] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2004] [Accepted: 08/25/2004] [Indexed: 11/20/2022] Open
Abstract
OBJECTIVE To determine the clinical phenotypes in carriers with probable disease-causing sequence variations in 1 of 6 genes established to cause Leber congenital amaurosis (LCA). DESIGN Observational prospective comparative study. PARTICIPANTS Thirty carriers with various probable disease-causing sequence variations in 1 of 6 genes known to cause LCA. METHODS After the establishment of various disease-causing sequence variations in 37 (33.6%) of 110 patients with LCA, we examined a number of carriers who were either parents or offspring and who were willing to participate in our study. Evaluations included assessment of visual acuity, slit-lamp biomicroscopy, dilated fundus examination, and full-field electroretinogram (ERG) measurements. MAIN OUTCOME MEASURES Dilated fundus examination and full-field ERGs. RESULTS Of the 30 carriers with probable disease-causing sequence variations for LCA, 5 (16.7%) carriers had an AIPL1 variation, 4 (13.3%) CRB1, 0 (0%) CRX, 5 (16.7%) GUCY2D, 9 (30%) RPE65, and 7 (23.3%) carriers had a RPGRIP1 variation. Twenty-nine (96.7%) carriers had 20/20 or better visual acuity in their better seeing eye with correction. Drusenlike deposits were more selectively observed in carriers with mutations in the AIPL1, CRB1, RPE65, and RPGRIP1 genes, whereas mild peripheral chorioretinal atrophy was only observed in AIPL1 and RPE65 carriers. A reduced dark-adapted isolated rod ERG response and/or maximal combined cone and rod response was recorded in carriers with mutations in the AIPL1, GUCY2D, and RPGRIP1 genes. A reduced light-adapted ERG response to a single-flash and/or 32-Hz flicker was recorded in carriers with mutations in the AIPL1, CRB1, GUCY2D, and RPGRIP1 genes. Overall, our cohort of LCA carriers did not describe significant subjective visual difficulties, including nyctalopia and/or photosensitivity. CONCLUSIONS The variation of phenotypic expression in carriers among 5 LCA genotypes indicates that there is considerable phenotypic overlap. However, phenotypic trends were noted in carriers' fundus findings and ERG responses for each genetic subtype. Observations of phenotypic associations with specific disease-causing sequence variations in carriers have potential practical value for molecular screening strategies of patients with LCA.
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Affiliation(s)
- Jennifer A Galvin
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois 60612, USA
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164
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Morrow EM, Furukawa T, Raviola E, Cepko CL. Synaptogenesis and outer segment formation are perturbed in the neural retina of Crx mutant mice. BMC Neurosci 2005; 6:5. [PMID: 15676071 PMCID: PMC548520 DOI: 10.1186/1471-2202-6-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2004] [Accepted: 01/27/2005] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In Leber's congenital amaurosis (LCA), affected individuals are blind, or nearly so, from birth. This early onset suggests abnormal development of the neural retina. Mutations in genes that affect the development and/or function of photoreceptor cells have been found to be responsible in some families. These examples include mutations in the photoreceptor transcription factor, Crx. RESULTS A Crx mutant strain of mice was created to serve as a model for LCA and to provide more insight into Crx's function. In this study, an ultrastructural analysis of the developing retina in Crx mutant mice was performed. Outer segment morphogenesis was found to be blocked at the elongation stage, leading to a failure in production of the phototransduction apparatus. Further, Crx-/- photoreceptors demonstrated severely abnormal synaptic endings in the outer plexiform layer. CONCLUSIONS This is the first report of a synaptogenesis defect in an animal model for LCA. These data confirm the essential role this gene plays in multiple aspects of photoreceptor development and extend our understanding of the basic pathology of LCA.
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Affiliation(s)
- Eric M Morrow
- Department of Genetics and Howard Hughes Medical Institute, Harvard Medical School, New Research Building, Room 360K, NRB, Room 360K, 77 Avenue Louis Pasteur, Boston, Massachusetts, 02115, USA
| | - Takahisa Furukawa
- Department of Genetics and Howard Hughes Medical Institute, Harvard Medical School, New Research Building, Room 360K, NRB, Room 360K, 77 Avenue Louis Pasteur, Boston, Massachusetts, 02115, USA
- The 4th Department, Osaka Bioscience Institute, 6-2-4 Furuedai, Suita, Osaka, Japan
| | - Elio Raviola
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, B2-201, Boston, Massachusetts, 02115, USA
| | - Constance L Cepko
- Department of Genetics and Howard Hughes Medical Institute, Harvard Medical School, New Research Building, Room 360K, NRB, Room 360K, 77 Avenue Louis Pasteur, Boston, Massachusetts, 02115, USA
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165
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Nishiguchi KM, Sokal I, Yang L, Roychowdhury N, Palczewski K, Berson EL, Dryja TP, Baehr W. A novel mutation (I143NT) in guanylate cyclase-activating protein 1 (GCAP1) associated with autosomal dominant cone degeneration. Invest Ophthalmol Vis Sci 2004; 45:3863-70. [PMID: 15505030 PMCID: PMC1475955 DOI: 10.1167/iovs.04-0590] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To identify pathogenic mutations in the guanylate cyclase-activating protein 1 (GCAP1) and GCAP2 genes and to characterize the biochemical effect of mutation on guanylate cyclase (GC) stimulation. METHODS The GCAP1 and GCAP2 genes were screened by direct sequencing for mutations in 216 patients and 421 patients, respectively, with various hereditary retinal diseases. A mutation in GCAP1 segregating with autosomal dominant cone degeneration was further evaluated biochemically by employing recombinant proteins, immunoblotting, Ca2+-dependent stimulation of GC, fluorescence emission spectra, and limited proteolysis in the absence and presence of Ca2+. RESULTS A novel GCAP1 mutation, I143NT (substitution of Ile at codon 143 by Asn and Thr), affecting the EF4 Ca2+-binding loop, was identified in a heterozygote father and son with autosomal dominant cone degeneration. Both patients had much greater loss of cone function versus rod function; previous histopathologic evaluation of the father's eyes at autopsy (age 75 years) showed no foveal cones but a few, scattered cones remaining in the peripheral retina. Biochemical analysis showed that the GCAP1-I143NT mutant adopted a conformation susceptible to proteolysis, and the mutant inhibited GC only partially at high Ca2+ concentrations. Individual patients with atypical or recessive retinitis pigmentosa (RP) had additional heterozygous GCAP1-T114I and GCAP2 gene changes (V85M and F150C) of unknown pathogenicity. CONCLUSIONS A novel GCAP1 mutation, I143NT, caused a form of autosomal dominant cone degeneration that destroys foveal cones by mid-life but spares some cones in the peripheral retina up to 75 years. Properties of the GCAP1-I143NT mutant protein suggested that it is incompletely inactivated by high Ca2+ concentrations as should occur with dark adaptation. The continued activity of the mutant GCAP1 likely results in higher-than-normal scotopic cGMP levels which may, in turn, account for the progressive loss of cones.
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Affiliation(s)
- Koji M. Nishiguchi
- Ocular Molecular Genetics Institute, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts
| | - Izabela Sokal
- Department of Ophthalmology, University of Washington, Seattle, Washington
| | - Lili Yang
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, Utah
| | - Nirmalya Roychowdhury
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, Utah
| | - Krzysztof Palczewski
- Department of Ophthalmology, University of Washington, Seattle, Washington
- Department of Pharmacology, University of Washington, Seattle, Washington
- Department of Chemistry, University of Washington, Seattle, Washington
| | - Eliot L. Berson
- Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts
| | - Thaddeus P. Dryja
- Ocular Molecular Genetics Institute, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts
| | - Wolfgang Baehr
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, Utah
- Department of Biology, University of Utah, Salt Lake City, Utah
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, Utah
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166
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Vittitow J, Borrás T. Genes expressed in the human trabecular meshwork during pressure-induced homeostatic response. J Cell Physiol 2004; 201:126-37. [PMID: 15281095 DOI: 10.1002/jcp.20030] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Physiological pressure inside the eye is maintained by a resistance mechanism provided by the trabecular meshwork tissue. In most cases, prolonged, elevated pressure leads to an eye pathology characterized by retinal ganglion cell (RGC) degeneration, optic nerve damage, and non-remedial blindness. We are investigating the regulation of trabecular meshwork genes in response to elevated pressure. Using perfused organ cultures from postmortem human donors, we have previously demonstrated the presence of a homeostatic mechanism at 2-4 days of pressure insult (Borrás et al. 2002, Invest Ophthalmol Vis Sci 43:33-40). Here, we sought to identify trabecular meshwork genes whose expression was altered during this homeostatic period. By macroarray hybridization, we compared the expression profiles of high-pressure (HP) and normal-pressure (NP) treated eyes from the same individual (n = 3 pairs). Our results identified 40 upregulated and 14 downregulated genes. The highest proportion of upregulated genes encoded proteins involved in signal transduction (32%). Among the potentially relevant genes, PIP 5K1C, VIP, tropomodulin, and MMP2 encoded mediators known to influence outflow resistance. Others encoded functions which are new for the trabecular meshwork, but which are intrinsic to unrelated tissues. These new mechanisms appear as they could be of benefit for trabecular meshwork function. Matrix Gla protein (MGP), perlecan, osteomodulin, and osteoblast-specific factor are essential in cartilage and bone physiology whereas spectrin and ICAM4 are specific for blood cells and crucial in maintaining their shape and adhesion. In addition, MGP transcripts were stimulated by extracellular calcium and downregulated by TGF-beta1. We propose that MGP might be an important player in the adaptive homeostatic mechanism by contributing to maintain a softer trabecular meshwork tissue and facilitate aqueous humor outflow.
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Affiliation(s)
- Jason Vittitow
- Department of Ophthalmology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
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167
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Perrault I, Hanein S, Gerber S, Barbet F, Ducroq D, Dollfus H, Hamel C, Dufier JL, Munnich A, Kaplan J, Rozet JM. Retinal dehydrogenase 12 (RDH12) mutations in leber congenital amaurosis. Am J Hum Genet 2004; 75:639-46. [PMID: 15322982 PMCID: PMC1182050 DOI: 10.1086/424889] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2004] [Accepted: 07/28/2004] [Indexed: 11/03/2022] Open
Abstract
Leber congenital amaurosis (LCA), the most early-onset and severe form of all inherited retinal dystrophies, is responsible for congenital blindness. Ten LCA genes have been mapped, and seven of these have been identified. Because some of these genes are involved in the visual cycle, we regarded the retinal pigment epithelium and photoreceptor-specific retinal dehydrogenase (RDH) genes as candidate genes in LCA. Studying a series of 110 unrelated patients with LCA, we found mutations in the photoreceptor-specific RDH12 gene in a significant subset of patients (4.1%). Interestingly, all patients harboring RDH12 mutations had a severe yet progressive rod-cone dystrophy with severe macular atrophy but no or mild hyperopia.
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Affiliation(s)
- Isabelle Perrault
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Sylvain Hanein
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Sylvie Gerber
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Fabienne Barbet
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Dominique Ducroq
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Helene Dollfus
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Christian Hamel
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Jean-Louis Dufier
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Arnold Munnich
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Josseline Kaplan
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
| | - Jean-Michel Rozet
- Unité de Recherches sur les Handicaps Génétiques de l’Enfant and Service d’Ophtalmologie, Hôpital Necker–Enfants Malades, Paris; Clinique Ophtalmologique, Hopitaux Universitaires de Strasbourg, Strasbourg; and Service d’Ophtalmologie, Montpellier, France
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168
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Sato M, Nakazawa M, Usui T, Tanimoto N, Abe H, Ohguro H. Mutations in the gene coding for guanylate cyclase-activating protein 2 (GUCA1B gene) in patients with autosomal dominant retinal dystrophies. Graefes Arch Clin Exp Ophthalmol 2004; 243:235-42. [PMID: 15452722 DOI: 10.1007/s00417-004-1015-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2004] [Revised: 07/05/2004] [Accepted: 07/28/2004] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND We investigated mutations in the gene coding for guanylate-cyclase activating protein 2 (GCAP2), also known as GUCA1B gene, in Japanese patients with retinitis pigmentosa (RP) and tried to identify phenotypic characteristics associated with mutations in the gene. SUBJECTS AND METHODS Genomic DNA samples from 63 unrelated patients with autosomal dominant retinitis pigmentosa (ADRP) and 33 patients with autosomal recessive retinitis pigmentosa (ARRP) were screened by single-strand conformational polymorphism analysis followed by direct sequencing. Clinical features associated with a mutation were demonstrated by visual acuity, visual field testing, fundus photography, and electroretinography. RESULTS A novel transitional mutation converting GGA to AGA at codon 157 (G157R) was identified. This mutation has been found in three index patients from three independent families. Phenotypic examination of seven members of the three families revealed that this mutation was associated with RP with or without macular involvement in five members, macular degeneration in one member, and asymptomatic normal phenotype in one member. In addition, previously unknown polymorphic changes including V29V, Y57Y, T87I, and L180L were identified. CONCLUSIONS A racial difference exists in the spectrum of mutations and/or polymorphisms in the GCAP 2 gene between British and Japanese populations. Our findings suggest that the mutation in the GCAP 2 gene can cause one form of autosomal dominant retinal dystrophy, with variable phenotypic expression and incomplete penetrance.
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Affiliation(s)
- Motoya Sato
- Department of Ophthalmology, Hirosaki University School of Medicine, Japan
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169
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Liu X, Bulgakov OV, Wen XH, Woodruff ML, Pawlyk B, Yang J, Fain GL, Sandberg MA, Makino CL, Li T. AIPL1, the protein that is defective in Leber congenital amaurosis, is essential for the biosynthesis of retinal rod cGMP phosphodiesterase. Proc Natl Acad Sci U S A 2004; 101:13903-8. [PMID: 15365173 PMCID: PMC518851 DOI: 10.1073/pnas.0405160101] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2004] [Indexed: 11/18/2022] Open
Abstract
Aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1) is a member of the FK-506-binding protein family expressed specifically in retinal photoreceptors. Mutations in AIPL1 cause Leber congenital amaurosis, a severe early-onset retinopathy that leads to visual impairment in infants. Here we show that knockdown of AIPL1 expression in mice also produces a retinopathy but over a more extended time course. Before any noticeable pathology, there was a reduction in the level of rod cGMP phosphodiesterase (PDE) proportional to the decrease in AIPL1 expression, whereas other photoreceptor proteins were unaffected. Consistent with less PDE in rods, flash responses had a delayed onset, a reduced gain, and a slower recovery of flash responses. We suggest that AIPL1 is a specialized chaperone required for rod PDE biosynthesis. Thus loss of AIPL1 would result in a condition that phenocopies retinal degenerations in the rd mouse and in a subgroup of human patients.
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Affiliation(s)
- Xiaoqing Liu
- Berman-Gund Laboratory for the Study of Retinal Degenerations, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA
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170
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Koenekoop RK. An overview of Leber congenital amaurosis: a model to understand human retinal development. Surv Ophthalmol 2004; 49:379-98. [PMID: 15231395 DOI: 10.1016/j.survophthal.2004.04.003] [Citation(s) in RCA: 186] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Leber congenital amaurosis is a congenital retinal dystrophy described almost 150 years ago. Today, Leber congenital amaurosis is proving instrumental in our understanding of the molecular events that determine normal and aberrant retinal development. Six genes have been shown to be mutated in Leber congenital amaurosis, and they participate in a wide variety of retinal pathways: retinoid metabolism (RPE65), phototransduction (GUCY2D), photoreceptor outer segment development (CRX), disk morphogenesis (RPGRIP1), zonula adherens formation (CRB1), and cell-cycle progression (AIPL1). Longitudinal studies of visual performance show that most Leber congenital amaurosis patients remain stable, some deteriorate, and rare cases exhibit improvements. Histopathological analyses reveal that most cases have extensive degenerative retinal changes, some have an entirely normal retinal architecture, whereas others have primitive, poorly developed retinas. Animal models of Leber congenital amaurosis have greatly added to understanding the impact of the genetic defects on retinal cell death, and response to rescue. Gene therapy for RPE65 deficient dogs partially restored sight, and provides the first real hope of treatment for this devastating blinding condition.
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Affiliation(s)
- Robert K Koenekoop
- McGill Ocular Genetics Laboratory, Montreal Children's Hospital, McGill University Health Center, Montreal, Quebec, Canada
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171
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Subbaraya I, Zhao C, Duda T. Structure and Ca2+ regulation of frog photoreceptor guanylate cyclase, ROS-GC1. Mol Cell Biochem 2004; 254:9-19. [PMID: 14674678 DOI: 10.1023/a:1027311811807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Rod outer segment membrane guanylate cyclase (ROS-GC) is a critical component of the vertebrate phototransduction machinery. In response to photoillumination, it senses a decline in free Ca(2+) levels from 500 to below 100 nM, becomes activated, and replenishes the depleted cyclic GMP pool to restore the dark state of the photoreceptor cell. It exists in two forms, ROS-GC1 and ROS-GC2. In outer segments, ROS-GCs sense fluctuations in Ca(2+) via two Ca(2+)-binding proteins, which have been termed GCAP1 and GCAP2. In the present study we report on the cloning of two ROS-GCs from the frog retinal cDNA library. These cyclases are the structural and functional counterparts of the mammalian ROS-GC1 and ROS-GC2. There is, however, an important difference between the regulation of mammalian and frog ROS-GC1: In contrast to the mammalian, the frog form does not require the myristoylated form of GCAP1 for its Ca(2+)-dependent modulation. This feature is not dependent upon the ability of frog GCAP1 to bind Ca(2+) because unmyristoylated GCAP1 mutants which do not bind Ca(2+), activate frog ROS-GC1. The findings establish frog as a suitable phototransduction model and show a facet of frog ROS-GC signaling, which is not shared by the mammalian form.
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Affiliation(s)
- Iswari Subbaraya
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, USA
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172
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Krumenacker JS, Hanafy KA, Murad F. Regulation of nitric oxide and soluble guanylyl cyclase. Brain Res Bull 2004; 62:505-15. [PMID: 15036565 DOI: 10.1016/s0361-9230(03)00102-3] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2002] [Accepted: 02/17/2003] [Indexed: 02/08/2023]
Abstract
Since the discoveries that have verified nitric oxide (NO) as an endogenously produced cell signaling molecule, research surrounding its production and mechanisms of action have been studied at an exponentially increasing rate. NO is produced by a family of enzymes termed the NO synthases (NOS), which are regulated independently by various stimuli. Once produced, NO can solicit numerous biological events by reacting with various metals, thiols, and oxygen species to modify proteins, DNA and lipids. One of the most biologically relevant actions of NO is its binding to the heme moiety in the heterodimeric enzyme, soluble guanylyl cyclase (sGC). Activation of sGC by NO results in the production of the second messenger molecule, 3',5'-cyclic guanosine monophosphate (cGMP), which can regulate numerous physiological events such as vasodilatation and neurotransmission. Here we will review the synthesis and fate of NO, and discuss the activation and regulation of the NO receptor, sGC.
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Affiliation(s)
- Joshua S Krumenacker
- Department of Integrative Biology and Pharmacology, Institute of Molecular Medicine, University of Texas Houston Medical School, 6431 Fannin Street, Houston, TX 77030, USA
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173
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Hanein S, Perrault I, Gerber S, Tanguy G, Barbet F, Ducroq D, Calvas P, Dollfus H, Hamel C, Lopponen T, Munier F, Santos L, Shalev S, Zafeiriou D, Dufier JL, Munnich A, Rozet JM, Kaplan J. Leber congenital amaurosis: comprehensive survey of the genetic heterogeneity, refinement of the clinical definition, and genotype-phenotype correlations as a strategy for molecular diagnosis. Hum Mutat 2004; 23:306-17. [PMID: 15024725 DOI: 10.1002/humu.20010] [Citation(s) in RCA: 247] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Leber congenital amaurosis (LCA) is the earliest and most severe form of all inherited retinal dystrophies, responsible for congenital blindness. Disease-associated mutations have been hitherto reported in seven genes. These genes are all expressed preferentially in the photoreceptor cells or the retinal pigment epithelium but they are involved in strikingly different physiologic pathways resulting in an unforeseeable physiopathologic variety. This wide genetic and physiologic heterogeneity that could largely increase in the coming years, hinders the molecular diagnosis in LCA patients. The genotyping is, however, required to establish genetically defined subgroups of patients ready for therapy. Here, we report a comprehensive mutational analysis of the all known genes in 179 unrelated LCA patients, including 52 familial and 127 sporadic (27/127 consanguineous) cases. Mutations were identified in 47.5% patients. GUCY2D appeared to account for most LCA cases of our series (21.2%), followed by CRB1 (10%), RPE65 (6.1%), RPGRIP1 (4.5%), AIPL1 (3.4%), TULP1 (1.7%), and CRX (0.6%). The clinical history of all patients with mutations was carefully revisited to search for phenotype variations. Sound genotype-phenotype correlations were found that allowed us to divide patients into two main groups. The first one includes patients whose symptoms fit the traditional definition of LCA, i.e., congenital or very early cone-rod dystrophy, while the second group gathers patients affected with severe yet progressive rod-cone dystrophy. Besides, objective ophthalmologic data allowed us to subdivide each group into two subtypes. Based on these findings, we have drawn decisional flowcharts directing the molecular analysis of LCA genes in a given case. These flowcharts will hopefully lighten the heavy task of genotyping new patients but only if one has access to the most precise clinical history since birth.
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Affiliation(s)
- Sylvain Hanein
- Unité de Recherches sur les Handicaps Génétiques de l'Enfant, Hôpital Necker-Enfants Malades, Paris, France
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174
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Abstract
Over the past decade, there has been an exponential increase in our knowledge of heritable eye conditions. Coincidentally, our ability to provide accurate genetic diagnoses has allowed appropriate counseling to patients and families. A summary of our current understanding of ocular genetics will prove useful to clinicians, researchers, and students as an introduction to the subject.
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Affiliation(s)
- Ian M MacDonald
- Department of Ophthalmology, University of Alberta, Edmonton, Alberta, Canada
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175
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Gilgenkrantz S. [Spontaneous activity of opsin, one of the causes of Leber congenital amaurosis]. Med Sci (Paris) 2004; 20:274-7. [PMID: 15067571 DOI: 10.1051/medsci/2004203274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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176
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Pignatelli V, Cepko CL, Strettoi E. Inner retinal abnormalities in a mouse model of Leber's congenital amaurosis. J Comp Neurol 2004; 469:351-9. [PMID: 14730587 DOI: 10.1002/cne.11019] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Leber's congenital amaurosis (LCA) is the earliest and most severe form in the world of genetic retinal dystrophy causing blindness. An animal model of LCA was recently created in which the cone-rod homeobox (crx) gene was disrupted using homologous recombination. Crx-/- mice display abnormal development of photoreceptors followed by their degeneration. We analyzed the morphology of inner retinal cells in crx-/- mice in order to evaluate the effects of abnormal photoreceptor development and death upon other retinal neurons. The identification of a time window during which inner retinal cells are still viable could be very important in view of the possibilities that photoreceptor transplantation or gene therapy might be used to restore vision in LCA. We used a combination of immunocytochemical and confocal microscopy techniques to screen the crx-/- inner retina and verify its morphological integrity after photoreceptor degeneration. We found significant morphological alterations in second-order neurons in crx-/- animals. The appearance of mutant retinas after photoreceptor death is indistinguishable from that of the retinal degeneration (rd/rd) mouse, a different genetic model of a retinal disease characterized by photoreceptor degeneration. However, at early stages of photoreceptor degeneration the morphology of retinal cells in the crx-/- mutant is considerably well preserved. It is likely that different genetic mechanisms that cause abnormal photoreceptor development and/or degeneration lead to a common pathway that determines second-order neuron modifications. The severity of modifications is linked to the timing of onset of the degeneration and appears to increase with time.
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MESH Headings
- Animals
- Animals, Newborn
- Cell Count
- Choline O-Acetyltransferase/metabolism
- Disease Models, Animal
- Embryo, Mammalian
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- Homeodomain Proteins/genetics
- Immunohistochemistry
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Nerve Tissue Proteins/metabolism
- Neurites/metabolism
- Neurons/metabolism
- Neurons/pathology
- Optic Atrophy, Hereditary, Leber/pathology
- Parvalbumins/metabolism
- Photoreceptor Cells/metabolism
- Photoreceptor Cells/pathology
- Protein Kinase C/metabolism
- Protein Kinase C-alpha
- Receptors, Metabotropic Glutamate/metabolism
- Receptors, Neurokinin-3/metabolism
- Retina/growth & development
- Retina/pathology
- Trans-Activators/genetics
- Tyrosine 3-Monooxygenase/metabolism
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Affiliation(s)
- Vincenzo Pignatelli
- Istituto di Neuroscienze del Consiglio Nazionale delle Ricerche (CNR), Laboratorio di Neurofisiologia, Area della Ricerca CNR, 56100 Pisa, Italy
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177
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Sitorus RS, Lorenz B, Preising MN. Analysis of three genes in Leber congenital amaurosis in Indonesian patients. Vision Res 2004; 43:3087-93. [PMID: 14611946 DOI: 10.1016/j.visres.2003.08.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
PURPOSE To assess the frequency, the pattern of disease causing mutations, and phenotypic variations in patients with Leber congenital amaurosis (LCA) from Indonesia. PATIENTS AND METHODS Twenty-one unrelated index cases with a clinical diagnosis of LCA were screened for mutations in the coding sequence of RetGC1, RPE65 and AIPL1 gene with single strand conformation polymorphism analysis followed by direct sequencing and restriction enzyme digestion. RESULTS Four novel disease causing mutations were identified: Three in the RPE65 gene (106del9bp, G32V and Y435C) in two of 21 index cases and one in the AIPL1 (K14E). Two of them were homozygous and one was compound-heterozygous. No disease causing mutation was identified in RetGC1. CONCLUSIONS The four novel disease causing mutations identified in this study confirmed the diagnosis of LCA which has not been recognized before in Indonesia. The frequency of RPE65 mutations was 9.5%; and of AIPL1 mutations 4.8%. This was in general accordance with previous studies reported from other countries. Unlike in those studies, no disease causing RetGC1 mutations could be identified in our patients. Phenotypically, the RPE65 and AIPL1 mutations identified in this study caused nearly total blindness by the second decade of life, but had a different onset of symptoms. The patients with the RPE65 mutations retained some useful visual function until the end of the first decade, which progressed to total blindness during the second decade of life, whereas the (homozygous) AIPL1 mutation was associated with nearly total blindness from infancy on. Therefore, RPE65 mutations have to be considered to cause early onset severe retinal degeneration (EOSRD), and AIPL1 mutations a form of LCA.
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Affiliation(s)
- Rita S Sitorus
- Department of Paediatric Ophthalmology, Strabismology and Ophthalmogenetics, Klinikum, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany.
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178
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Abstract
The mature eye is a complex organ that develops through a highly organized process during embryogenesis. Alterations in its genetic programming can lead to severe disorders that become apparent at birth or shortly afterwards; for example, one-half of the cases of blindness in children have a genetic cause. This review outlines the genetic basis of eye development, as determined by mutation analysis in patients and in model organisms. A better understanding of how this intricate organ develops at the genetic and cellular level is central to our understanding of the pathologies that afflict it.
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Affiliation(s)
- Jochen Graw
- GSF-National Research Center for Environment and Health, Institute of Developmental Genetics, D-85764 Neuherberg, Germany.
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179
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Barbet F, Gerber S, Hakiki S, Perrault I, Hanein S, Ducroq D, Tanguy G, Dufier JL, Munnich A, Rozet JM, Kaplan J. A first locus for isolated autosomal recessive optic atrophy (ROA1) maps to chromosome 8q. Eur J Hum Genet 2003; 11:966-71. [PMID: 14508503 DOI: 10.1038/sj.ejhg.5201070] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
In contrast to the frequent dominant optic atrophies (DOAs) in which the neuropathy is usually an isolated event, isolated recessive optic atrophies (ROAs) are very uncommon and have been described as severe congenital or early infantile conditions. To date, two loci for isolated DOA have been mapped, of which one was ascribed to mutations in the OPA1 gene. Conversely, no isolated autosomal ROA locus had previously been localised. Here, we report a large multiplex consanguineous family of French origin affected with an early onset but slowly progressive form of isolated OA. A genome-wide search for homozygosity allowed the localisation of the disease-causing gene to chromosome 8q21-q22 (Zmax of 3.41 at theta=0 for D8S270), in a 12 Mb interval flanked by markers D8S1702 and D8S1794. This localisation excludes allelism of the disease with both isolated DOAs, on one hand, or all known syndromic forms of ROA, on the other hand, supporting the mapping of a first gene for isolated autosomal ROA (ROA1) on the long arm of chromosome 8.
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Affiliation(s)
- Fabienne Barbet
- Unité de Recherches sur les Handicaps, Génétiques de l'Enfant, Hôpital Necker-Enfants Malades, Paris, France
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180
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Hwang JY, Lange C, Helten A, Höppner-Heitmann D, Duda T, Sharma RK, Koch KW. Regulatory modes of rod outer segment membrane guanylate cyclase differ in catalytic efficiency and Ca(2+)-sensitivity. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:3814-21. [PMID: 12950265 DOI: 10.1046/j.1432-1033.2003.03770.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In rod phototransduction, cyclic GMP synthesis by membrane bound guanylate cyclase ROS-GC1 is under Ca(2+)-dependent negative feedback control mediated by guanylate cyclase-activating proteins, GCAP-1 and GCAP-2. The cellular concentration of GCAP-1 and GCAP-2 approximately sums to the cellular concentration of a functional ROS-GC1 dimer. Both GCAPs increase the catalytic efficiency (kcat/Km) of ROS-GC1. However, the presence of a myristoyl group in GCAP-1 has a strong impact on the regulation of ROS-GC1, this is in contrast to GCAP-2. Catalytic efficiency of ROS-GC1 increases 25-fold when it is reconstituted with myristoylated GCAP-1, but only by a factor of 3.4 with nonmyristoylated GCAP-1. In contrast to GCAP1, myristoylation of GCAP-2 has only a minor effect on kcat/Km. The increase with both myristoylated and nonmyristoylated GCAP-2 is 10 to 13-fold. GCAPs also confer different Ca(2+)-sensitivities to ROS-GC1. Activation of the cyclase by GCAP-1 is half-maximal at 707 nM free [Ca(2+)], while that by GCAP-2 is at 100 nM. The findings show that differences in catalytic efficiency and Ca(2+)-sensitivity of ROS-GC1 are conferred by GCAP-1 and GCAP-2. The results further indicate the concerted operation of two 'GCAP modes' that would extend the dynamic range of cyclase regulation within the physiological range of free cytoplasmic Ca(2+) in photoreceptor cells.
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Affiliation(s)
- Ji-Young Hwang
- Institut für Biologische Informationsverarbeitung 1, Forschungszentrum Jülich, Jülich, Germany
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181
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Heegaard S, Rosenberg T, Preising M, Prause JU, Bek T. An unusual retinal vascular morphology in connection with a novel AIPL1 mutation in Leber's congenital amaurosis. Br J Ophthalmol 2003; 87:980-3. [PMID: 12881340 PMCID: PMC1771788 DOI: 10.1136/bjo.87.8.980] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AIMS To report a case of an unusual retinal vascular morphology in connection with a novel AIPL1 mutation in a patient with Leber's congenital amaurosis (LCA). METHODS A patient with LCA and no light perception from birth had both eyes enucleated at the age of 22 years because of excruciating pain. Mutation analysis was performed on known LCA genes. The eyes were processed for casts of the vascular tree, routine histopathology, and electron microscopy. RESULTS A novel H82Y (244C-->T) mutation and a H90D (286G-->C) polymorphism were detected in exon 2 of the AIPL1 gene. Both the cast and the histopathological examination showed dilated retinal vessels, mainly venules, primarily localised in the posterior pole. In the mid-peripheral retina the density of capillaries on the arteriolar side of the microcirculatory units was significantly decreased. The vascular system was seen to gradually attenuate towards the retinal periphery, and to stop at a zone located approximately 4 mm from the ora serrata along the whole circumference. In this zone pigmented aggregates characteristic of retinitis pigmentosa were seen to ensheath the retinal vessels. The photoreceptors were almost totally absent and retinal gliosis was present. A decreased number of ganglion cells and an increased vacuolisation of the nerve fibre layer were observed. The retinal pigment cells and Bruch's membrane appeared normal in all regions. CONCLUSION An unusual retinal vascular morphology in an LCA patient is presented and possible pathogenic mechanisms of the findings are discussed.
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Affiliation(s)
- S Heegaard
- Eye Pathology Institute, University of Copenhagen, Denmark.
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182
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Newbold RJ, Deery EC, Payne AM, Wilkie SE, Hunt DM, Warren MJ. Guanylate cyclase activating proteins, guanylate cyclase and disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 514:411-38. [PMID: 12596936 DOI: 10.1007/978-1-4615-0121-3_25] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
A range of cone and cone-rod dystrophies (CORD) have been observed in man, caused by mutations in retinal guanylate cyclase 1 (RetGC1) and guanylate cyclase activating protein 1 (GCAP 1). The CORD causing mutations in RetGC1 are located at a mutation "hot spot" within the dimerisation domain, where R838 is the key residue. Three disease causing mutations have been found in human GCAP1, resulting in cone or cone-rod degeneration. All three mutations are dominant in their effect although the mechanism by which the P50L mutation exerts its influence remains unclear although it might act due to a haplo-insufficiency, arising from increased susceptibility to protease activity and increased thermal instability. In contrast, loss of Ca2+ sensitivity appears to be the main cause of the diseased state for the Y99C and E155G mutations. The cone and cone-rod dystrophies that are caused by mutations in RetGC1 or GCAP1 arise from a perturbation of the delicate balance of Ca2+ and cGMP within the photoreceptor cells and it is this disruption that is believed to cause cell death. The diseases caused by mutations in RetGC1 and GCAP1 prominently affect cones, consistent with the higher concentrations of these proteins in cone cells.
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Affiliation(s)
- Richard J Newbold
- School of Biological Sciences, Queen Mary, University of London, Mile End Road, London, E1 4NS, UK
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183
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Mendez A, Chen J. Mouse models to study GCAP functions in intact photoreceptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 514:361-88. [PMID: 12596933 DOI: 10.1007/978-1-4615-0121-3_22] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In photoreceptor cells cGMP is the second messenger that transduces light into an electrical response. Regulation of cGMP synthesis by Ca2+ is one of the key mechanisms by which Ca2+ exerts negative feedback to the phototransduction cascade in the process of light adaptation. This Ca2+ feedback to retinal guanylyl cyclases (Ret-GCs) is conferred by the guanylate cyclase-activating proteins (GCAPs). Mutations in GCAP1 that disrupt the Ca2+ regulation of Ret-GCs in vitro have been associated with severe human vision disorders. This chapter focuses on recent data obtained from biochemical and electrophysiological studies of GCAP1/GCAP2 knockout mice and other GCAP transgenic mice, addressing: 1. the quantitative aspects of the Ca2+-feedback to Ret-GCs in regulating the light sensitivity and adaptation in intact rods; 2. functional differences between GCAP1 and GCAP2 in intact rod photoreceptors; and 3. whether GCAP mutants with impaired Ca2+ binding lead to retinal disease in vivo by constitutive activation of Ret-GCs and elevation of intracellular cGMP, as predicted from in vitro studies.
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Affiliation(s)
- Ana Mendez
- The Mary D. Allen Laboratory for Vision Research, Doheny Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9112, USA
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184
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Koch KW. Target recognition of guanylate cyclase by guanylate cyclase-activating proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 514:349-60. [PMID: 12596932 DOI: 10.1007/978-1-4615-0121-3_21] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
Guanylate cyclase-activating proteins (GCAPs) control the activity of membrane bound guanylate cyclases in vertebrate photoreceptor cells. They form a permanent complex with guanylate cyclase 1 (ROS-GC1) at low and high Ca2+-concentrations. Five different target regions of GCAP-1 have been identified in ROS-GC1 at rather distant sites. These findings could indicate a multipoint attachment site for GCAP-1 or, alternatively, the presence of transient binding sites with short contact to GCAP-1. In addition some data are consistent with the operation of one or more transducer units, that represent regulatory regions without being direct binding sites. A permanent ROS-GC1/GCAP-1 complex is physiologically significant, since it allows a very short response time of cyclase activity when the intracellular Ca2+-concentration changes. Thereby, activation of cyclase participates in speeding up the recovery of the photoresponse after illumination and restores the circulating dark current.
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Affiliation(s)
- Karl-Wilhelm Koch
- Institut für Biologische Informationsverarbeitung 1, Forschungszentrum Jülich, D-52425 Jülich, Germany.
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185
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Keen TJ, Mohamed MD, McKibbin M, Rashid Y, Jafri H, Maumenee IH, Inglehearn CF. Identification of a locus (LCA9) for Leber's congenital amaurosis on chromosome 1p36. Eur J Hum Genet 2003; 11:420-3. [PMID: 12734549 DOI: 10.1038/sj.ejhg.5200981] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Leber's congenital amaurosis (LCA) is the most common cause of inherited childhood blindness and is characterised by severe retinal degeneration at or shortly after birth. We have identified a new locus, LCA9, on chromosome 1p36, at which the disease segregates in a single consanguineous Pakistani family. Following a whole genome linkage search, an autozygous region of 10 cM was identified between the markers D1S1612 and D1S228. Multipoint linkage analysis generated a lod score of 4.4, strongly supporting linkage to this region. The critical disease interval contains at least 5.7 Mb of DNA and around 50 distinct genes. One of these, retinoid binding protein 7 (RBP7), was screened for mutations in the family, but none was found.
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186
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Mohamed MD, Topping NC, Jafri H, Raashed Y, McKibbin MA, Inglehearn CF. Progression of phenotype in Leber's congenital amaurosis with a mutation at the LCA5 locus. Br J Ophthalmol 2003; 87:473-5. [PMID: 12642313 PMCID: PMC1771622 DOI: 10.1136/bjo.87.4.473] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2002] [Indexed: 11/04/2022]
Abstract
BACKGROUND Leber's congenital amaurosis (LCA) accounts for 5% of inherited retinal disease and is usually inherited as an autosomal recessive trait. Genetic and clinical heterogeneity exist. Mutations have been described in the RPE65, CRB1, RPGRIP1, AIPL1, GUCY2D, and CRX genes and other pedigrees show linkage to the LCA3 and LCA5 loci. The latter is a new locus which maps to 6q11-q16. The ocular findings and the evolution of the macula staphyloma are described in five members of a Pakistani family with consanguinity and a mutation in the LCA5 gene. METHODS 13 family members including five affected individuals consented to DNA analysis and ocular examination including fundal photography. RESULTS Ocular abnormalities are described. The most striking feature was the progression of macula abnormalities in three brothers resulting in a colobomatous appearance in the eldest compared to only mild atrophy in the youngest. The phenotypic pattern of this mutation in this Pakistani family contrasts with the "Old Order River Brethren" who were of Swiss descent, in whom the mutation was first described. CONCLUSION The evolution of a new phenotypic picture is presented to a mutation in LCA5.
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Affiliation(s)
- M D Mohamed
- Department of Ophthalmology, St James's University Hospital, Beckett Street, Leeds LS7 7TF, UK.
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187
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Khaliq S, Abid A, Hameed A, Anwar K, Mohyuddin A, Azmat Z, Shami SA, Ismail M, Mehdi SQ. Mutation screening of Pakistani families with congenital eye disorders. Exp Eye Res 2003; 76:343-8. [PMID: 12573663 DOI: 10.1016/s0014-4835(02)00304-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
To map the disease loci several Pakistani families suffering from autosomal recessive retinitis pigmentosa with preserved para-arteriolar retinal pigment epithelium and Leber congenital amaurosis (LCA) were analyzed. Analysis revealed close genetic linkage between the disease phenotype of some of the families (3330RP, 111RP and 010LCA) and the microsatellite markers on chromosome 1q31. Mutation screening of the candidate gene CRB1 revealed a G to A transversion in exon 7 in arRP family 330RP and a T to C substitution in another arRP family, 111RP. In exon 9 of the CRB1 gene a T to C transversion was found in the family suffering from LCA (010LCA). The LCA phenotype of another family (011LCA) in which the CRB1 locus was excluded, showed linkage with microsatellite markers D17S1294 and D17S796 on chromosome 17p13.1. The association of the candidate gene GUCY2D (17p13.1) with the disease phenotype was excluded as no disease-associated mutation was found in any of its exons. Mutation screening of another candidate gene, AIPL1 located in the same region, showed a novel homozygous C to A substitution in exon 2. These sequence changes are unique for the Pakistani families and some of these have not been reported previously.
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Affiliation(s)
- Shagufta Khaliq
- Dr A. Q. Khan Research Laboratories, Biomedical and Genetic Engineering Division, 24 Mauve area, P.O. Box 2891, Islamabad, Pakistan.
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188
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Milam AH, Barakat MR, Gupta N, Rose L, Aleman TS, Pianta MJ, Cideciyan AV, Sheffield VC, Stone EM, Jacobson SG. Clinicopathologic effects of mutant GUCY2D in Leber congenital amaurosis. Ophthalmology 2003; 110:549-58. [PMID: 12623820 DOI: 10.1016/s0161-6420(02)01757-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE To study the retinal degeneration in an 11 -year-old patient with Leber congenital amaurosis (LCA) caused by mutation in GUCY2D. STUDY DESIGN Comparative human tissue study. PARTICIPANTS Two subjects with LCA; postmortem eye from one LCA patient and three normal donors. METHODS Clinical and visual function studies were performed between the ages of 6 and 10 years in the LCA eye donor and at age 6 in an affected sibling. Genomic DNA was screened for mutations in known LCA genes. The retina of the 11 -year-old subject with LCA was compared with normal retinas from donors age 3 days, 18 years, and 53 years. The tissues were processed for histopathologic studies and immunofluorescence with retinal cell-specific antibodies. RESULTS Vision in both siblings at the ages examined was limited to severely impaired cone function. Mutation in the GUCY2D gene was identified in both siblings. Histopathologic study revealed rods and cones without outer segments in the macula and far periphery. The cones formed a monolayer of cell bodies, but the rods were clustered and had sprouted neurites in the periphery. Rods and cones were not identified in the midperipheral retina. The inner nuclear layer appeared normal in thickness throughout the retina, but ganglion cells were reduced in number. CONCLUSIONS An 11-year-old subject with LCA caused by mutant GUCY2D had only light perception but retained substantial numbers of cones and rods in the macula and far periphery. The finding of numerous photoreceptors at this age may portend well for therapies designed to restore vision at the photoreceptor level.
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MESH Headings
- Adolescent
- Blindness/congenital
- Child
- DNA Mutational Analysis
- Electroretinography
- Female
- Fluorescent Antibody Technique, Indirect
- Genotype
- Guanylate Cyclase/genetics
- Humans
- Infant, Newborn
- Middle Aged
- Mutation
- Optic Atrophy, Hereditary, Leber/enzymology
- Optic Atrophy, Hereditary, Leber/genetics
- Optic Atrophy, Hereditary, Leber/pathology
- Pedigree
- Photoreceptor Cells, Vertebrate/pathology
- Polymorphism, Single-Stranded Conformational
- Retinal Degeneration/enzymology
- Retinal Degeneration/genetics
- Retinal Degeneration/pathology
- Visual Acuity
- Visual Fields
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Affiliation(s)
- Ann H Milam
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania School of Medicine, 51 North 39th Street, Philadelphia, PA 19104, USA
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189
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Abstract
Leber's congenital amaurosis (LCA) is a clinically and genetically heterogeneous disorder characterized by severe loss of vision at birth. It accounts for 10-18% of cases of congenital blindness. Some patients exhibit only blindness of retinal origin whereas others show evidence of a multi-systemic involvement. We review the literature relating to this severe disorder, highlighting unresolved questions, in particular the nature of the association of LCA with mental retardation and with systemic findings and syndromic pictures. In recent years, genetic advances in the diagnosis of LCA have opened up new horizons, also from a therapeutic point of view. A better understanding of this pathology would be valuable for paediatric neurologists.
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Affiliation(s)
- Elisa Fazzi
- Department of Child Neurology and Psychiatry, IRCCS C Mondino Foundation-Institute of Neurology, University of Pavia, Italy.
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190
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Perrault I, Gerber S, Hanein S, Picaud S, Rozet JM, Dufier JL, Munnich A, Sahel J, Kaplan J. Leber Congenital Amaurosis — Genotyping Required for Possible Inclusion in a Clinical Trial. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 533:69-77. [PMID: 15180249 DOI: 10.1007/978-1-4615-0067-4_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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191
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Dejneka NS, Surace EM, Bennett J. Gene therapy for Leber congenital amaurosis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 533:415-22. [PMID: 15180293 DOI: 10.1007/978-1-4615-0067-4_53] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Nadine S Dejneka
- University of Pennsylvania, Scheie Eye Institute, Philadelphia, PA 19104-6069, USA.
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192
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Prenatal Human Ocular Degeneration Occurs in Leber’s Congenital Amaurosis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003. [DOI: 10.1007/978-1-4615-0067-4_8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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193
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Gerber S, Perrault I, Hanein S, Shalev S, Zlotogora J, Barbet F, Ducroq D, Dufier J, Munnich A, Rozet J, Kaplan J. A novel mutation disrupting the cytoplasmic domain of CRB1 in a large consanguineous family of Palestinian origin affected with Leber congenital amaurosis. Ophthalmic Genet 2002; 23:225-35. [PMID: 12567265 DOI: 10.1076/opge.23.4.225.13879] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Leber congenital amaurosis (LCA) is a genetically heterogeneous autosomal recessive condition responsible for congenital blindness or greatly impaired vision since birth. Eight LCA loci have been mapped, but only six out of eight genes have been hitherto identified. A genome-wide screen for homozygosity was conducted in a large consanguineous family originating from Palestine, for which no mutation was found in any of the six known LCA genes and that excluded the LCA3 and LCA5 loci. Evidence for homozygosity, however, was found in all affected patients of the family on chromosome 1q31, a region in which the human homologue of the Drosophila melanogaster crumbs gene (CRB1) has been mapped. Consequently, we proposed a hypothesis that the disease-causing mutation in this family might lie in an unexplored region of this LCA gene. As a matter of fact, while no mutation was found in any of the 11 CRB1 exons originally reported, we identified a 10-bp (del 4121-4130) deletion segregating with the disease in a later reported 12th exon lying in the 3' end of the gene. Interestingly, this deletion disrupts an amino acid sequence that was shown to be crucial for the function of the protein in the Drosophila counterpart (CRB).
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Affiliation(s)
- Sylvie Gerber
- Unité de Recherches sur les Handicaps Génétiques de l'Enfant, Hôpital Necker-Enfants Malades, Paris, France
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194
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Abstract
A nation-wide registration of Danish cases of retinitis pigmentosa (RP) provided 1890 persons diagnosed during the period 1850-1989. Prevalent at 1 January 1988 were 1301 persons (1:3943) comprising a multitude of different RP-types. Age specific prevalence rates demonstrated increasing rates of RP during the first four decades of life and a rather stable prevalence over the next 20-30 years. Corrected for incompleteness, a late decrease was found, reflecting an incomplete ascertainment of the oldest patients. A moving average method indicated an even later steady state value for the age-specific prevalence. The Danish prevalence figures were standardized according to the WHO World Standardized Prevalence Rates and compared with large studies from the USA and UK. No statistically significant difference was found. Usher syndrome was present in 12% of all RP-cases and Bardet-Biedl syndrome comprised 5%. Mental retardation was found in 144 cases (11%), mostly characterized by atypical RP. Nineteen per cent of patients affected by nonsystemic RP had an onset later than 30 years of age, whereas only a few per cent of persons with systemic RP had an RP onset after age 30 years. The Mendelian inheritance type of all cases was evaluated according to an unambiguous genetic classification, finding a larger amount of X-linked RP compared with other studies. Among nonsystemic RP-cases, 14.3% were found to be inherited as an X-linked trait whereas only 8.4% were autosomal dominantly inherited. The largest fraction was, as in previous materials, the simplex group (isolated cases) comprising 42.9% of the nonsystemic RP patients. Some factors influencing the results are discussed, with special emphasis on the problems associated with precise definitions of the Mendelian inheritance groups. A diagram according to the author's definition was constructed as a guideline ready for clinical application.
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Affiliation(s)
- Marianne Haim
- National Eye Clinic for the Visually Impaired, Rymarksvej I, DK-2900 Hellerup, Denmark
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195
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Iannaccone A, McIntosh N, Ciccarelli ML, Baldi A, Mutolo PA, Tedesco SA, Engle EC. Familial unilateral Brown syndrome. Ophthalmic Genet 2002; 23:175-84. [PMID: 12324876 DOI: 10.1076/opge.23.3.175.7882] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE To report a family in which three siblings have unilateral late-onset Brown syndrome. METHODS The entire nuclear family underwent ophthalmologic evaluation. Orbital imaging and systemic workup were obtained to rule out local or systemic causes. Historic information was obtained from unavailable family members. The family's Brown syndrome trait was analyzed for linkage to the known congenital fibrosis syndrome loci and the CFEOM2 gene, ARIX, was sequenced in affected individuals. RESULTS All affected siblings developed left-sided Brown syndrome, worse on awakening, at 12-13 years of age. No evidence of Brown syndrome could be identified in other family members, either by exam or history. No abnormalities of the trochlear-tendon complex could be documented. Haplotype analysis of the Brown syndrome phenotype was consistent with recessive inheritance at the DURS1 locus and dominant inheritance with reduced penetrance at the DURS1, DURS2, and FEOM1 loci. No mutations were detected in CFEOM2 gene, ARIX. CONCLUSIONS We propose that a genetically determined predisposition to Brown syndrome is likely responsible for the observed manifestations in this family and that late age of onset and intermittent manifestations do not distinguish acquired from hereditary Brown syndrome. The pattern of inheritance of the Brown phenotype in this family could be either autosomal recessive or autosomal dominant with reduced penetrance. Our analysis only permitted the exclusion of the FEOM3 locus and the FEOM2 gene, ARIX. Future genetic studies of additional Brown syndrome families should shed additional light on the genetic basis of this disorder.
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196
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Porto FBO, Perrault I, Hicks D, Rozet JM, Hanoteau N, Hanein S, Kaplan J, Sahel JA. Prenatal human ocular degeneration occurs in Leber's congenital amaurosis (LCA2). J Gene Med 2002; 4:390-6. [PMID: 12124981 DOI: 10.1002/jgm.278] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Leber's congenital amaurosis (LCA) encompasses the most precocious and severe forms of inherited retinal dystrophy, displaying very significant visual handicap at or soon after birth. Among the currently identified mutations, alterations in the gene coding for retinal pigment epithelium 65-kDa protein (RPE65) lead to LCA2. Existing animal models for LCA2 (RPE65(-/-) null mice and naturally occurring RPE65(-/-) Briard dogs) exhibit near normal retinal histology at birth, although no recordable photofunction can be detected. Structural degeneration in both cases occurs with delayed onset, cone death generally preceding that of rods. METHODS We obtained retinal tissue from a voluntarily aborted embryo of an LCA2 carrier in order to compare histopathology and immunohistochemistry with age-matched normal foetal retina. RESULTS Compared to normal retinas, affected retina displayed cell loss and thinning of the outer nuclear (photoreceptor) layer, decreased immunoreactivity for key phototransduction proteins, and aberrant synaptic and inner retinal organisation. The gene mutation abolished detectable expression of RPE65 within the retinal pigment epithelium (RPE) of affected eyes, and ultrastructural examination revealed the presence of lipid and vesicular inclusions not seen in normal RPE. In addition, mutant eyes demonstrated thickening, detachment and collagen fibril disorganisation in the underlying Bruch's membrane, and the choroid was distended and abnormally vascularised, in comparison with controls. CONCLUSIONS Such data contrast with the late-onset ocular changes observed in animal models, indicating caution should be exercised when inferring human retinal pathophysiology from information based on other species.
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Affiliation(s)
- Fernanda B O Porto
- Laboratoire de Physiopathologie Cellulaire et Moléculaire de la Rétine, INSERM Université Louis Pasteur EMI 9918, Clinique Médicale A, CHUR Strasbourg, BP. 426, 1 Place de l'Hôpital, 67091 Strasbourg Cedex, France
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197
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Van Hooser JP, Liang Y, Maeda T, Kuksa V, Jang GF, He YG, Rieke F, Fong HKW, Detwiler PB, Palczewski K. Recovery of visual functions in a mouse model of Leber congenital amaurosis. J Biol Chem 2002; 277:19173-82. [PMID: 11897783 PMCID: PMC1470660 DOI: 10.1074/jbc.m112384200] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The visual process is initiated by the photoisomerization of 11-cis-retinal to all-trans-retinal. For sustained vision the 11-cis-chromophore must be regenerated from all-trans-retinal. This requires RPE65, a dominant retinal pigment epithelium protein. Disruption of the RPE65 gene results in massive accumulation of all-trans-retinyl esters in the retinal pigment epithelium, lack of 11-cis-retinal and therefore rhodopsin, and ultimately blindness. We reported previously (Van Hooser, J. P., Aleman, T. S., He, Y. G., Cideciyan, A. V., Kuksa, V., Pittler, S. J., Stone, E. M., Jacobson, S. G., and Palczewski, K. (2000) Proc. Natl. Acad. Sci. U. S. A. 97, 8623-8628) that in Rpe65-/- mice, oral administration of 9-cis-retinal generated isorhodopsin, a rod photopigment, and restored light sensitivity to the electroretinogram. Here, we provide evidence that early intervention by 9-cis-retinal administration significantly attenuated retinal ester accumulation and supported rod retinal function for more than 6 months post-treatment. In single cell recordings rod light sensitivity was shown to be a function of the amount of regenerated isorhodopsin; high doses restored rod responses with normal sensitivity and kinetics. Highly attenuated residual rod function was observed in untreated Rpe65-/- mice. This rod function is likely a consequence of low efficiency production of 11-cis-retinal by photo-conversion of all-trans-retinal in the retina as demonstrated by retinoid analysis. These studies show that pharmacological intervention produces long lasting preservation of visual function in dark-reared Rpe65-/- mice and may be a useful therapeutic strategy in recovering vision in humans diagnosed with Leber congenital amaurosis caused by mutations in the RPE65 gene, an inherited group of early onset blinding and retinal degenerations.
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Affiliation(s)
- J Preston Van Hooser
- Department of Ophthalmology, University of Washington, Seattle, Washington 98195, USA
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198
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Koenekoop RK, Loyer M, Dembinska O, Beneish R. Visual improvement in Leber congenital amaurosis and the CRX genotype. Ophthalmic Genet 2002; 23:49-59. [PMID: 11910559 DOI: 10.1076/opge.23.1.49.2200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE In order to determine genotype-phenotype correlations in Leber congenital amaurosis (LCA), we analyzed the phenotype and genotype of 250 LCA children. We identified a heterozygous CRX mutation in an affected mother and son, and describe the ocular phenotype of the proband from birth through infancy to age 11 years. METHODS Best-corrected Snellen visual acuities, electroretinograms (ERGs), and Goldmann visual fields were measured, while SSCP and direct sequencing were done for genotyping. RESULTS The proband had congenital nystagmus, amaurotic, paradoxical pupils, and arteriolar narrowing, without a pigmentary retinopathy. The child had very poor fixation and wandering nystagmus at age 5 months, but had measurable vision at age 6 years. Snellen visual acuities were 20/900 at that time, and slowly improved to 20/150 by age 11 years. Perimetry revealed 60 degrees fields with the V4e target at ages 9 and 10 years, with a new 20 degrees inferior island to the III4e target. ERGs at 5 and 8 months were non-detectable, while the photopic ERGs at age 10 years and again at 11 years showed measurable cone a- and b-waves. At age 47, the phenotype of the affected mother consisted of hand motion vision, a pigmentary retinopathy, and non-detectable visual fields and ERGs. We identified a heterozygous CRX mutation, A177Delta1bp (529delG), in both affected individuals, which is predicted to cause a frameshift and introduces a premature termination codon at position 186. CONCLUSIONS We report a CRX genotype with an ocular phenotype that consists of spontaneous, marked visual improvement in the proband from birth to age 11 years, which is unlike the previous six reports of LCA patients with the CRX genotype.
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Affiliation(s)
- Robert K Koenekoop
- The Children's Vision Center, Montreal Children's Hospital and Research Institute, McGill University, Montreal, PQ, Canada.
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Omran H, Sasmaz GÜ, Häffner K, Volz A, Olbrich H, Melkaoui R, Otto E, Wienker TF, Korinthenberg R, Brandis M, Antignac C, Hildebrandt F. Identification of a gene locus for Senior-Løken syndrome in the region of the nephronophthisis type 3 gene. J Am Soc Nephrol 2002; 13:75-79. [PMID: 11752023 DOI: 10.1681/asn.v13175] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Senior-Løken syndrome is an autosomal recessive disease with the main features of nephronophthisis (NPH) and Leber congenital amaurosis. The gene for adolescent nephronophthisis (NPHP3) was recently localized to chromosome 3q21-q22. The hypothesis was tested that Senior-Løken syndrome (SLS) might localize to the same region by studying a kindred of German ancestry with extended consanguinity and typical findings of SLS. Twenty highly polymorphic markers located in the vicinity of the NPHP3 genetic region were tested. Haplotype analysis revealed homozygosity by descent in affected individuals, and linkage analysis yielded a parametric maximum multipoint logarithm of likelihood of odds (LOD) score of 3.14, thus identifying the first locus for SLS. The SLS1 locus is flanked by D3S1587 and D3S621 and contains a 14-cM interval that contains the whole critical NPHP3 region. Three additional families with SLS were studied, and evidence for genetic heterogeneity in one of them was found. Localization of a SLS locus to the region of NPHP3 opens the possibilities of both diseases arising by mutations within the same pleiotropic gene or two adjacent genes.
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Affiliation(s)
- Heymut Omran
- *University Children's Hospital Freiburg and Institute for Medical Biometry, Informatics and Epidemology, University of Bonn, Bonn, Germany; Inserm U423, Hôpital Necker-Enfants Malades, Paris, France
| | - GÜrsel Sasmaz
- *University Children's Hospital Freiburg and Institute for Medical Biometry, Informatics and Epidemology, University of Bonn, Bonn, Germany; Inserm U423, Hôpital Necker-Enfants Malades, Paris, France
| | - Karsten Häffner
- *University Children's Hospital Freiburg and Institute for Medical Biometry, Informatics and Epidemology, University of Bonn, Bonn, Germany; Inserm U423, Hôpital Necker-Enfants Malades, Paris, France
| | - Andreas Volz
- *University Children's Hospital Freiburg and Institute for Medical Biometry, Informatics and Epidemology, University of Bonn, Bonn, Germany; Inserm U423, Hôpital Necker-Enfants Malades, Paris, France
| | - Heike Olbrich
- *University Children's Hospital Freiburg and Institute for Medical Biometry, Informatics and Epidemology, University of Bonn, Bonn, Germany; Inserm U423, Hôpital Necker-Enfants Malades, Paris, France
| | - Rachid Melkaoui
- *University Children's Hospital Freiburg and Institute for Medical Biometry, Informatics and Epidemology, University of Bonn, Bonn, Germany; Inserm U423, Hôpital Necker-Enfants Malades, Paris, France
| | - Edgar Otto
- *University Children's Hospital Freiburg and Institute for Medical Biometry, Informatics and Epidemology, University of Bonn, Bonn, Germany; Inserm U423, Hôpital Necker-Enfants Malades, Paris, France
| | - Thomas F Wienker
- *University Children's Hospital Freiburg and Institute for Medical Biometry, Informatics and Epidemology, University of Bonn, Bonn, Germany; Inserm U423, Hôpital Necker-Enfants Malades, Paris, France
| | - Rudolf Korinthenberg
- *University Children's Hospital Freiburg and Institute for Medical Biometry, Informatics and Epidemology, University of Bonn, Bonn, Germany; Inserm U423, Hôpital Necker-Enfants Malades, Paris, France
| | - Matthias Brandis
- *University Children's Hospital Freiburg and Institute for Medical Biometry, Informatics and Epidemology, University of Bonn, Bonn, Germany; Inserm U423, Hôpital Necker-Enfants Malades, Paris, France
| | - Corinne Antignac
- *University Children's Hospital Freiburg and Institute for Medical Biometry, Informatics and Epidemology, University of Bonn, Bonn, Germany; Inserm U423, Hôpital Necker-Enfants Malades, Paris, France
| | - Friedhelm Hildebrandt
- *University Children's Hospital Freiburg and Institute for Medical Biometry, Informatics and Epidemology, University of Bonn, Bonn, Germany; Inserm U423, Hôpital Necker-Enfants Malades, Paris, France
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Abstract
To gain insight into the genetic mechanisms of photoreceptor development, we analyzed a collection of zebrafish mutations characterized by early photoreceptor cell loss. The mutant defects impair outer segment formation and are accompanied by an abnormal distribution of visual pigments. Rods and different cone types display defects of similar severity suggesting that genetic pathways common to all photoreceptors are affected. To investigate whether these phenotypes involve cell-cell interaction defects, we analyzed genetically mosaic animals. Interaction of niezerka photoreceptors with wild-type tissues improves the survival of mutant cells and restores their elongated morphology. In contrast, cells carrying mutations in the loci brudas, elipsa, fleer, and oval retain their defective phenotypes in a wild-type environment indicating cell-autonomy. These experiments identify distinct phenotypic categories of photoreceptor mutants and indicate that zebrafish photoreceptor defects involve both cell-autonomous and cell-nonautonomous mechanisms.
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Affiliation(s)
- Geoffrey Doerre
- Department of Ophthalmology, Harvard Medical School, 243 Charles Street, Boston, MA 02114, USA
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