SEARCH · PubMed Health

Results for “Cone dystrophy”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources

PubMed1998

Linkage analysis of X-linked cone-rod dystrophy: localization to Xp11.4 and definition of a locus distinct from RP2 and RP3.

Progressive X-linked cone-rod dystrophy (COD1) is a retinal disease affecting primarily the cone photoreceptors. The COD1 locus originally was localized, by the study of three independent families, to a region between Xp11.3 and Xp21.1, encompassing the retinitis pigmentosa (RP) 3 locus. We have refined the COD1 locus to a limited region of Xp11.4, using two families reported elsewhere and a new extended family. Genotype analysis was performed by use of eight microsatellite markers (tel-M6CA, DXS1068, DXS1058, DXS993, DXS228, DXS1201, DXS1003, and DXS1055-cent), spanning a distance of 20 cM. Nine-point linkage analysis, by use of the VITESSE program for X-linked disorders, established a maximum LOD score (17.5) between markers DXS1058 and DXS993, spanning 4.0 cM. Two additional markers, DXS977 and DXS556, which map between DXS1058 and DXS993, were used to further narrow the critical region. The RP3 gene, RPGR, was excluded on the basis of two obligate recombinants, observed in two independent families. In a third family, linkage analysis did not exclude the RPGR locus. The entire coding region of the RPGR gene from two affected males from family 2 was sequenced and was found to be normal. Haplotype analysis of two family branches, containing three obligate recombinants, two affected and one unaffected, defined the COD1 locus as distal to DXS993 and proximal to DXS556, a distance of approximately 1.0 Mb. This study excludes COD1 as an allelic variant of RP3 and establishes a novel locus that is sufficiently defined for positional cloning.

Alleles↗

PubMed2006

Canine RPGRIP1 mutation establishes cone-rod dystrophy in miniature longhaired dachshunds as a homologue of human Leber congenital amaurosis.

Cone-rod dystrophy 1 (cord1) is a recessive condition that occurs naturally in miniature longhaired dachshunds (MLHDs). We mapped the cord1 locus to a region of canine chromosome CFA15 that is syntenic with a region of human chromosome 14 (HSA14q11.2) containing the retinitis pigmentosa GTPase regulator-interacting protein 1 (RPGRIP1) gene. Mutations in RPGRIP1 have been shown to cause Leber congenital amaurosis, a group of retinal dystrophies that represent the most common genetic causes of congenital visual impairment in infants and children. Using the newly available canine genome sequence we sequenced RPGRIP1 in affected and carrier MLHDs and identified a 44-nucleotide insertion in exon 2 that alters the reading frame and introduces a premature stop codon. All affected and carrier dogs within an extended inbred pedigree were homozygous and heterozygous, respectively, for the mutation. We conclude the mutation is responsible for cord1 and demonstrate that this canine disease is a valuable model for exploring disease mechanisms and potential therapies for human Leber congenital amaurosis.

Animals↗

PubMed2002

Identification of a locus on chromosome 2q11 at which recessive amelogenesis imperfecta and cone-rod dystrophy cosegregate.

A consanguineous Arab pedigree in which recessive amelogenesis imperfecta (AI) and cone-rod dystrophy cosegregate, was screened for linkage to known retinal dystrophy and tooth abnormality loci by genotyping neighbouring microsatellite markers. This analysis resulted in linkage with a maximum lod score of 7.03 to the marker D2S2187 at the achromatopsia locus on chromosome 2q11, and haplotype analysis placed the gene(s) involved in a 2 cM/5 Mb interval between markers D2S2209 and D2S373. The CNGA3 gene, known to be involved in achromatopsia, lies in this interval but thorough analysis of its coding sequence revealed no mutation. Furthermore, affected individuals in four consanguineous recessive pedigrees with AI but without CRD were heterozygous at this locus, excluding it as a common cause of non-syndromic recessive AI. It remains to be established whether this pedigree is segregating two closely linked mutations causing disparate phenotypes or whether a single defect is causing pathology in both teeth and eyes.

Amelogenesis Imperfecta↗

PubMed2006

Phenotype of autosomal dominant cone-rod dystrophy due to the R838C mutation of the GUCY2D gene encoding retinal guanylate cyclase-1.

AIMS: To describe the phenotype of members of a large Caucasian British family affected by autosomal dominant cone-rod dystrophy due to an R838C mutation in the guanylate cyclase 2D (GUCY2D) gene encoding retinal guanylate cyclase-1 (RETGC-1). METHODS: Retrospective review of 29 patients from four generations of the same family. RESULTS: Visual symptoms usually commenced in childhood. Only two patients, aged 14 and 25 years, had visual acuity compatible with driving. Of the 12 patients aged over 40 years, eight (66%) had vision of counting fingers or worse and were eligible for blind registration in the UK. Of the 29 patients, 18 (62%) had myopia greater than 5 D in at least one eye. Most had discernible macular changes on biomicroscopy, which varied from subtle RPE change to gross macular atrophy. All patients who underwent computerised perimetry exhibited a central or paracentral scotoma with normal peripheral field of vision. Of the 21 patients who underwent electrodiagnostic testing, all exhibited decreased cone function, but rod function was normal in 12 (57%) patients. CONCLUSION: We believe this report highlights the importance of phenotype-genotype correlation in cone and cone-rod dystrophies. Increased understanding of the varying phenotypes associated with different genetic mutations allows appropriate counselling of patients. In addition, the phenotypic characterisation of the natural history of these conditions may prove valuable in the future should therapeutic interventions become available.

Adolescent↗

PubMed2005

[SCA-7. Cone-rod dystrophy in the context of an hereditary ataxia].

CLINICAL CASE: A 21-year-old male presented with bilateral loss of visual acuity within the last year, and cerebellar ataxia since childhood. Two members of his family had a similar disorder. Examination showed bilateral central scotomas, as well as an electroretinogram pattern and optic coherence tomography images consistent with cone-rod dystrophy. Molecular analysis by PCR amplification and genotyping of the SCA7 gene established the diagnosis of SCA-7. DISCUSSION: SCA-7 is a polyglutamine expansion disorder and the only spinocerebellar ataxia that shows a cone-rod dystrophy phenotype, which probably results from interference with the action of specific cone-rod genes.

Adult↗

PubMed2004

Microarray-based mutation analysis of the ABCA4 (ABCR) gene in autosomal recessive cone-rod dystrophy and retinitis pigmentosa.

Mutations in the ABCA4 gene have been associated with autosomal recessive Stargardt disease (STGD1), cone-rod dystrophy (CRD), and retinitis pigmentosa (RP). We employed a recently developed genotyping microarray, the ABCR400-chip, to search for known ABCA4 mutations in patients with isolated or autosomal recessive CRD (54 cases) or RP (90 cases). We performed detailed ophthalmologic examinations and identified at least one ABCA4 mutation in 18 patients (33%) with CRD and in five patients (5.6%) with RP. Single-strand conformation polymorphism (SSCP) analysis and subsequent DNA sequencing revealed four novel missense mutations (R24C, E161K, P597S, G618E) and a novel 1-bp deletion (5888delG). Ophthalmoscopic abnormalities in CRD patients ranged from minor granular pigmentary changes in the posterior pole to widespread atrophy. In 12 patients with recordable electroretinogram (ERG) tracings, a cone-rod pattern was detected. Three patients demonstrated progression from a retinal dystrophy resembling STGD1 to a more widespread degeneration, and were subsequently diagnosed as CRD. In addition to a variable degree of atrophy, all RP patients displayed ophthalmologic characteristics of classic RP. When detectable, ERG recordings in these patients demonstrated rod-cone patterns of photoreceptor degeneration. In conclusion, in this study, we show that the ABCA4 mutation chip is an efficient first screening tool for arCRD.

ATP-Binding Cassette Transporters↗

PubMed1986

Blood-retinal barrier function in patients with cone or cone-rod dystrophy.

We assessed blood-retinal barrier function by vitreous fluorophotometry in 24 patients with either cone or cone-rod dystrophy who were segregated into three subgroups. Compared with a normal population, the patients demonstrated increased vitreous fluorescence (breakdown of the blood-retinal barrier) that positively correlated with peripheral pigmentary changes and an appreciable reduction in electroretinographic scotopic b-wave amplitude. A unique subgroup of three women with supernormal electroretinographic scotopic b-wave amplitudes to a high-intensity stimulus had an abnormal increase in permeability of the blood-retinal barrier even without peripheral pigmentary fundus changes.

Adolescent↗

PubMed1996

Autosomal dominant cone-rod dystrophy associated with mutations in codon 244 (Asn244His) and codon 184 (Tyr184Ser) of the peripherin/RDS gene.

OBJECTIVE: To characterize clinical findings associated with mutations in codon 244 (Asn244His) and codon 184 (Tyr184Ser) of the peripherin/RDS gene. DESIGN: Case reports with clinical features and results of fluorescein angiography, electroretinography, kinetic visual field testing, and DNA analysis. SETTING: University medical center. PATIENTS: Four affected members of two Japanese families with autosomal dominant cone-rod dystrophy associated with transversion mutations in codon 244 (Asn244His) and codon (Tyr184Ser) of the peripherin/RDS gene. RESULTS: Characteristic features included the initial symptoms of decreased visual acuity, macular degeneration, central or paracentral scotoma, cone-mediated electroretinographic responses that were more impaired than rod-mediated responses, and pigmentary degeneration in the midperipheral retina in the late stage. These phenotypic features corresponded to cone-rod dystrophy type 2a by the classification of Szlyk and associates. CONCLUSIONS: The Asn244His and Tyr184Ser mutations in the peripherin/RDS gene cause con-rod dystrophy type 2a. These findings imply that a mutation in codon 244 or codon 184 of the peripherin/RDS gene affects the functions and/or structural stability of cones and rods.

Adult↗

PubMed1999

Biochemical analysis of a dimerization domain mutation in RetGC-1 associated with dominant cone-rod dystrophy.

Mutations in the photoreceptor membrane guanylyl cyclase RetGC-1 have been linked to autosomal dominant cone-rod dystrophy. Three mutations were identified that alter strictly conserved residues within the RetGC-1 dimerization domain, a region predicted to form an amphipathic alpha-helical coil. Here we report on a biochemical characterization of one of the mutations, a substitution of cysteine for arginine at residue 838. We generated this mutation in vitro and measured its catalytic activity and sensitivity to guanylyl cyclase activating protein 1 (GCAP-1) and GCAP-2. The R838C substitution has several effects. It reduces the overall catalytic ability of RetGC-1 and dramatically reduces stimulation by GCAP-2, although GCAP-2 still appears to interact with the protein. The R838C substitution also increases the apparent affinity of RetGC-1 for GCAP-1 and alters the Ca(2+) sensitivity of the GCAP-1 response, allowing the mutant to be stimulated by GCAP-1 at higher Ca(2+) concentrations than wild type. The diminished response to GCAP-2, which we propose is not likely the cause of cone-rod degeneration in these patients, is interesting mechanistically because it separates the ability to bind a specific GCAP from the ability to be stimulated by it, and it also discriminates between the mechanisms of activation of GCAP-1 vs. GCAP-2. We suggest that the gain-of-function effects of R838C on RetGC-1 stimulated by GCAP-1, which are dominant in vitro and may cause an abnormal increase in cGMP synthesis in dark-adapted photoreceptors, may be the cause of the cone-rod degeneration.

Amino Acid Sequence↗

PubMed2002

Spinocerebellar ataxia type 7 (SCA7) shows a cone-rod dystrophy phenotype.

Autosomal dominant spinocerebellar ataxia 7 is associated with retinal degeneration. SCA7, the causative gene, encodes ataxin-7, a ubiquitous 892 amino acid protein of variable sub-cellular localization, and the disease is due to expansion of an unstable CAG repeat in the coding region of the gene. Recent increases in understanding of the mechanisms ofSCA7 -related retinopathy from in vitro and murine model studies prompted us to perform a detailed study of the retinal phenotype of affected members of a family with SCA7 mutation (45-47 CAG repeats). There was a spectrum of severity from mild to severe dysfunction. Early functional abnormalities were at both photoreceptor and post-receptoral levels. When cone and rod photoreceptor dysfunction was present, it was approximately equal. Regional retinal dysfunction was evident: there was more dysfunction centrally than peripherally with least effect in the midperiphery. In vivo cross-sectional retinal images with optical coherence tomography showed an early disease stage of altered foveal lamination (abnormal area of low reflectivity splitting the outer retina-choroidal complex) accompanied in the parafovea by reduced retinal thickness. Later disease stages showed foveal and parafoveal retinal thinning. The phenotype in this family with SCA7 is that of a cone-rod dystrophy. These observations increase interest in a recent hypothesis that ataxin-7 may interfere with the function of CRX (cone-rod homeobox), a transcription factor regulating photoreceptor genes and a cause of a cone-rod dystrophy phenotype in man.

Adult↗

PubMed2005

A novel GCAP1 missense mutation (L151F) in a large family with autosomal dominant cone-rod dystrophy (adCORD).

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.

Adolescent↗

PubMed2004

Cloning of the canine ABCA4 gene and evaluation in canine cone-rod dystrophies and progressive retinal atrophies.

PURPOSE: To characterize a novel early onset canine retinal disease, and evaluate the ATP-binding cassette transporter gene ABCA4 as a potential candidate gene in this and other canine retinal degenerations. METHODS: Retinal disease was characterized ophthalmoscopically and electroretinographically in two pit bull terrier dogs and their purpose-bred descendants. All 50 exons of the canine ABCA4 gene were amplified, cloned and sequenced from retinal mRNA of a normal, a carrier and an affected animal, and polymorphisms identified. The latter were used to search for association between ABCA4 and retinal disease both within the study pedigrees and in additional canine breeds segregating retinal degenerations. RESULTS: The disease derived from either founder is distinguished by early, severe, and rapidly progressive loss of cone function accompanied by progressive rod loss that is only relatively slower. Cloning and comparative sequencing of ABCA4 identified six point mutations, none of which were obviously pathogenic. Crossbreeding studies revealed that the diseases in the two founders, although similar, are nonallelic. Pedigree analysis of segregating polymorphisms revealed dissociation between ABCA4 and both retinal phenotypes. CONCLUSIONS: The early, severe cone dysfunction in these diseases distinguish them from other forms of canine Progressive Retinal Atrophy. The development of a research population segregating these diseases presents two large animal models for the heterogenous human diseases termed cone-rod dystrophies. Analysis of the canine ABCA4 homolog gene documented its sequence and identified a set of point mutations that were used to exclude this gene as causal to these canine cone-rod dystrophies.

ATP-Binding Cassette Transporters↗

PubMed1981

Autosomal dominant cone-rod dystrophy: a linkage study with 17 biochemical and serological markers.

Five generations of a family with autosomal-dominant cone-rod dystrophy (CRD) with complete penetrance have been previously studied extensively clinically. The young members of this family were reevaluated, and blood from 73 available family members was studied with 17 biochemical and serological markers. A total of 25 relatives was found to be affected. Linkage between the gene for CRD in this family and the markers studied could not be established by maximum likelihood analysis.

Adolescent↗

PubMed2003

Genomic organisation and alternative splicing of human RIM1, a gene implicated in autosomal dominant cone-rod dystrophy (CORD7).

A mutation has been identified in the Rab3A-interacting molecule (RIM1) gene in CORD7, an autosomal dominant cone-rod dystrophy that localises to chromosome 6q14. The G to A point mutation results in an Arg844His substitution in the C(2)A domain of the protein that segregates with disease. This mutation is absent in over 200 control chromosomes, indicating that it is not a common polymorphism, and the almost complete sequence conservation of the C(2)A domain between human and rat RIM1 is consistent with a disease role for the change. RIM1 is expressed in brain and photoreceptors of the retina where it is localised to the pre-synaptic ribbons in ribbon synapses. The RIM1 gene is composed of at least 35 exons, spans 577 kb of genomic DNA, and encodes a protein of up to 1693 residues. The transcript shows extensive alternative splicing involving exons 17, 21-26 and 28-30.

Alternative Splicing↗

PubMed2006

Novel triple missense mutations of GUCY2D gene in Japanese family with cone-rod dystrophy: possible use of genotyping microarray.

PURPOSE: To report a novel mutation in the GUCY2D gene in a Japanese family with autosomal dominant cone-rod dystrophy (adCORD), and to examine the possible use of arrayed primer extension (APEX)-based genotyping chip in detecting mutations. METHODS: Genomic DNA was extracted from the peripheral blood of family members with adCORD. It was PCR-amplified, fragmented, and hybridized to APEX-based genotyping microarrays on which known disease-associated sequence variations were arrayed for patients with early-onset retinal dystrophy. All coding exons of the GUCY2D gene were directly sequenced. The PCR amplicon carrying a novel mutation was subcloned, and each clone was sequenced. RESULTS: Five single nucleotide polymorphisms in AIPL1, RPGRIP1, and GUCY2D were detected in the proband by microarray screening, and all were validated by direct sequencing. A novel heterozygous triple missense mutation of c.2540_2542delinsTCC (p.Gln847_Lys848delinsLeuGln amino acid substitutions) was found in both the proband and his father, and the three nucleotide changes were located on the same chromosome. Electroretinography (ERGs) demonstrated a significant reduction in rod function and a complete absence of cone function in both affected individuals. CONCLUSIONS: A novel heterozygous triple consecutive missense mutation in the GUCY2D gene has been linked to adCORD. Our study demonstrates that the APEX-based gene screening can be used to identify simultaneously disease-modifying sequence changes as well as disease-causing mutations, once proper and comprehensive sites of sequence variations of the disease are arrayed.

Aged↗

PubMed2000

Functional characterization of missense mutations at codon 838 in retinal guanylate cyclase correlates with disease severity in patients with autosomal dominant cone-rod dystrophy.

Three different mutations in codon 838 of GUCY2D, the gene for retinal guanylate cyclase 1, have been linked to autosomal dominant cone-rod dystrophy at the CORD6 locus. To examine the relationship between enzyme activity and disease severity, the three disease-causing substitutions (R838C, R838H and R838S) and four artificial mutations (R838A, R838E, R838L and R838K) were generated. Assay of GCAP1-stimulated cyclase activity in vitro shows that, compared with wild-type, R838E, R838L and R838K possess only low activity, whereas R838A, R838C, R838H and R838S have activity equal or superior to wild-type at low Ca(2+) concentrations. These four latter mutants showed a higher apparent affinity for GCAP1 than did wild-type. The Ca(2+) sensitivity of the GCAP1 activation was also altered with marked residual activity at high Ca(2+), the effect increasing: wild-type < R838C < R838H << R838A < R838S. Within the photoreceptor, this would result in a failure to inactivate cyclase activity at high physiological Ca(2+ )concentrations. Amongst the three disease-associated mutations, the effect correlates directly with disease severity. The wild-type and R838H mutant displayed a difference in pH sensitivity, with the mutant showing a higher specific activity with pH > 6.0. Site 838 is in the dimerization domain that forms a coiled-coil in the active protein. A computer-aided structure prediction of this region indicates that R838 in the wild-type breaks the structure at four helical turns, and there is an increasing tendency for the structure to continue for further turns in the order R838C < R838H,S,K << R838E < R838A < R838L.

Amino Acid Substitution↗

PubMed2005

Histopathologic study of X-linked cone-rod dystrophy (CORDX1) caused by a mutation in the RPGR exon ORF15.

PURPOSE: To evaluate the donor retina of a patient with X-linked cone-rod dystrophy caused by an RPGR exon ORF15 mutation. DESIGN: Histopathologic study of the retina. METHODS: The eye of a 69-year-old man was fixed at 1.6 hours postmortem and processed for histopathology and immunocytochemistry. RESULTS: Grossly, the macula was atrophic with a bull's-eye appearance. The remaining retina showed postmortem edema but no intraretinal pigment. Microscopically, the macular retinal pigment epithelium was absent focally and had pigmentary changes elsewhere. Cones and rods were absent from the perifovea and reduced with shortened outer segments elsewhere in the macula. In the remainder of the retina, cones but not rods were reduced and all photoreceptor outer segments were shortened. CONCLUSIONS: The abnormalities in both cone and rod photoreceptors confirm the importance of RPGR in both cell types but leaves unresolved how various exon ORF15 mutations lead to different clinical phenotypes.

Aged↗

PubMed2000

Novel locus for autosomal recessive cone-rod dystrophy CORD8 mapping to chromosome 1q12-Q24.

PURPOSE: To map the disease locus of a two-generation, consanguineous Pakistani family with autosomal recessive cone-rod dystrophy (arCRD). All affected individuals had night blindness, deterioration of central vision, photophobia, epiphora in bright light, and problems with color distinction. Fundoscopy revealed marked macular degeneration and attenuation of retinal vessels. Mild pigmentary changes were present in the periphery. METHODS: Genomic DNA was amplified across the polymorphic microsatellite poly-CA regions identified by markers. Alleles were assigned to individuals that allowed calculation of LOD scores using the Cyrillic (Cherwell Scientific, Oxford, UK) and MLINK (accessed from ftp://linkage. rockefeller.edu/softeware/linkage/) software programs. The cellular retinoic acid-binding protein 2 (CRABP2), cone transducin alpha-subunit (GNAT2), potassium inwardly rectifying channel, subfamily J, member 10 (KCNJ10), genes were analyzed by heteroduplex analysis and direct sequencing for mutations. RESULTS: A new locus for arCRD (CORD8) has been mapped to chromosome 1q12-q24. A maximum two-point LOD score of 4.22 was obtained with marker D1S2635 at recombination fraction of theta = 0.00. Two critical recombinations in the pedigree positioned this locus to a region flanked by markers D1S457 and D1S2681. A region of homozygosity was observed within the loci D1S442 and D1S2681, giving a probable critical disease interval of 21 cM. Mutation screening of the three candidate genes CRABP2, GNAT2, and KCNJ10 revealed no disease-associated mutations. CONCLUSIONS: The findings therefore suggest that this phenotype maps to a new locus and is due to an as yet uncharacterized gene within the 1q12-q24 chromosomal region.

Adolescent↗