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1.
Zhonghua Yan Ke Za Zhi ; 58(5): 376-379, 2022 May 11.
Artigo em Chinês | MEDLINE | ID: mdl-35511665

RESUMO

The proband was an 8-year-old boy, complaining of progressively decreased vision in both eyes for 3 years. The electroretinogram was characterized by supernormal rod response. While the responses of the rod and cone system were reduced, the amplitudes of dark-adapted electroretinogram responses at a high intensity were supernormal. A homozygous non-frameshift deletion variant c.1002-1004del (p. L335del) in KCNV2 was found by the Next Generation Sequencing using a custom designed panel. His father was a heterozygous carrier of this variant. In silico analysis indicated the variant was harmful. The proband was diagnosed as cone dystrophy type 3B which also known as cone dystrophy with supernormal rod response.


Assuntos
Distrofia de Cones , Canais de Potássio de Abertura Dependente da Tensão da Membrana , Retinite Pigmentosa , Criança , Eletrorretinografia , Humanos , Masculino , Células Fotorreceptoras Retinianas Cones/fisiologia
3.
Eur J Ophthalmol ; 32(1): 664-672, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33706576

RESUMO

PURPOSE: To describe the clinical, electrophysiological, and genetic findings of three Portuguese families with a rare variant in the KCNV2 gene resulting in "cone dystrophy with supernormal rod responses" (CDSRR). METHODS: Retrospective clinical revision of five individuals from three unrelated families with CDSRR. Ophthalmological examination was described in all patients and included color vision testing, fundus photography, fundus autofluorescence (FAF) imaging, spectral domain-optical coherence tomography (SD-OCT), pattern electroretinogram (ERG), and full-field ERG. The mutational screening of the KCNV2 gene was performed with Sanger and Next Generation Sequencing. RESULTS: All patients showed childhood-onset photophobia and progressive visual acuity loss with varying degrees of severity. In multimodal imaging, various degrees of retinal pigment epithelium disturbances and outer retinal atrophy, which tend to be worst with advancing age, were observed. Molecular screening identified a rare presumed truncating variant (p.Glu209Ter) in homozygosity in two families and in compound heterozygosity in a third family. Three patients showed ERG changes characteristic of CDSRR, however, two patients presented with incomplete electrophysiological features of the disease. CONCLUSION: A rare variant in the KCNV2 gene was identified in five patients from three Portuguese families. This variant often leads to a severe and progressive form of retinopathy. Considerable variability in the ERG responses among patients with this KCNV2 variant was observed.


Assuntos
Distrofia de Cones , Canais de Potássio de Abertura Dependente da Tensão da Membrana , Retinite Pigmentosa , Eletrorretinografia , Humanos , Portugal , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genética , Estudos Retrospectivos , Tomografia de Coerência Óptica
4.
Optom Vis Sci ; 99(2): 195-201, 2022 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-34897229

RESUMO

SIGNIFICANCE: Cone dystrophies and cone-rod dystrophies are a group of rare inherited pathologies characterized by degeneration of cone photoreceptors and subsequent rod involvement. The identification of causative genes is essential for diagnosis, and advanced imaging is acquiring great value in the characterization of the different phenotypic expressions. PURPOSE: We describe genotype-phenotype associations of an autosomal recessive ABCA4-associated cone dystrophy using multimodal imaging. CASE REPORT: A 34-year-old woman presented with progressive visual acuity decay. Visual acuity was 20/32 for her right eye and 20/25 for her left eye. A central scotoma was detected on a 10-2 Humphrey visual field in both eyes. Funduscopy revealed perifoveal retinal pigment epithelial changes, and fundus autofluorescence using blue excitation light showed decreased autofluorescence in the central fovea of both eyes with surrounding annular ring of increased autofluorescence in the perifoveal zone; green excitation light fundus autofluorescence was more accurate in the characterization of the size, perimeter, and circularity of central hypofluorescent lesions. Optical coherence tomography revealed an incomplete focal cavitation in both foveas, and optical coherence tomography angiography images showed a reduction in the superficial and deep capillary plexus density, an increased foveal avascular area, and subtle voids in choriocapillaris blood flow. Electroretinography was consistent with cone dystrophy, and molecular testing revealed the alteration of the ABCA4 gene. CONCLUSIONS: The identification of an incomplete focal cavitation could alert the clinician to consider early ABCA4 central cone dystrophy. The patient in this case also exhibited reduced vessel density in the foveal area. Both of these characteristics could be important features related to the underlying genetic mutation.


Assuntos
Distrofia de Cones , Distrofias de Cones e Bastonetes , Transportadores de Cassetes de Ligação de ATP/genética , Distrofia de Cones/patologia , Distrofias de Cones e Bastonetes/diagnóstico , Distrofias de Cones e Bastonetes/genética , Distrofias de Cones e Bastonetes/patologia , Eletrorretinografia , Feminino , Angiofluoresceinografia , Humanos , Imagem Multimodal , Mutação , Fenótipo , Células Fotorreceptoras Retinianas Cones/patologia , Tomografia de Coerência Óptica/métodos
5.
Int J Mol Sci ; 22(19)2021 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-34639157

RESUMO

Guanylate cyclase-activating protein 1 (GCAP1), encoded by the GUCA1A gene, is a neuronal calcium sensor protein involved in shaping the photoresponse kinetics in cones and rods. GCAP1 accelerates or slows the cGMP synthesis operated by retinal guanylate cyclase (GC) based on the light-dependent levels of intracellular Ca2+, thereby ensuring a timely regulation of the phototransduction cascade. We found a novel variant of GUCA1A in a patient affected by autosomal dominant cone dystrophy (adCOD), leading to the Asn104His (N104H) amino acid substitution at the protein level. While biochemical analysis of the recombinant protein showed impaired Ca2+ sensitivity of the variant, structural properties investigated by circular dichroism and limited proteolysis excluded major structural rearrangements induced by the mutation. Analytical gel filtration profiles and dynamic light scattering were compatible with a dimeric protein both in the presence of Mg2+ alone and Mg2+ and Ca2+. Enzymatic assays showed that N104H-GCAP1 strongly interacts with the GC, with an affinity that doubles that of the WT. The doubled IC50 value of the novel variant (520 nM for N104H vs. 260 nM for the WT) is compatible with a constitutive activity of GC at physiological levels of Ca2+. The structural region at the interface with the GC may acquire enhanced flexibility under high Ca2+ conditions, as suggested by 2 µs molecular dynamics simulations. The altered interaction with GC would cause hyper-activity of the enzyme at both low and high Ca2+ levels, which would ultimately lead to toxic accumulation of cGMP and Ca2+ in the photoreceptor outer segment, thus triggering cell death.


Assuntos
Distrofia de Cones/patologia , GMP Cíclico/metabolismo , Proteínas Ativadoras de Guanilato Ciclase/genética , Guanilato Ciclase/metabolismo , Mutação , Retina/enzimologia , Células Fotorreceptoras Retinianas Bastonetes/metabolismo , Adolescente , Cálcio/metabolismo , Criança , Distrofia de Cones/genética , Distrofia de Cones/metabolismo , Feminino , Humanos , Transdução de Sinal Luminoso , Masculino , Pessoa de Meia-Idade , Linhagem , Transdução de Sinais
6.
Mol Genet Genomic Med ; 9(10): e1795, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34535971

RESUMO

BACKGROUND: Cone dystrophy with supernormal rod response (CDSRR) is an autosomal recessive retinal disorder characterized by myopia, dyschromatopsia, nyctalopia, photophobia, and nystagmus. CDSRR is caused by mutations in KCNV2, the gene encoding for an electrically silent Kv subunit (Kvs) named Kv8.2. METHODS: A Chinese CDSRR family was recruited. Complete ophthalmology clinical examinations were performed to clarify the phenotype. Genetic examination was underwent using whole exome sequencing (WES). In addition, a candidate gene was validated by Sanger sequencing. Expression analysis in vitro including immunoblotting, quantitative real-time PCR (qRT-PCR), and co-immunoprecipitation experiments was performed to investigate the pathogenic mechanism of the identified gene variants. RESULTS: WES identified two KCNV2 heterozygous mutations from the proband. Sanger sequencing validated that the patient's parents had, respectively, carried those two mutations. Further in vitro functional experiments indicated that the mutated alleles had led the Kv8.2 proteins to fail in expressing and interacting with the Kv2.1 protein, respectively. CONCLUSIONS: This study expanded the KCNV2 mutation spectrum. It can also be deduced that CDSRR has a broad heterogeneity. It is further confirmed that the inability expression of Kv8.2 proteins and the failure of Kv8.2 proteins to interact with Kv2.1 may have accounted for the etiology of CDSRR based on previous studies and this study.


Assuntos
Distrofia de Cones/diagnóstico , Distrofia de Cones/genética , Heterozigoto , Mutação , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genética , Células Fotorreceptoras Retinianas Bastonetes/metabolismo , Células Fotorreceptoras Retinianas Bastonetes/patologia , Adulto , China , Análise Mutacional de DNA , Família , Estudos de Associação Genética , Predisposição Genética para Doença , Testes Genéticos , Humanos , Masculino , Imagem Óptica , Linhagem , Fenótipo , Tomografia de Coerência Óptica , Testes Visuais , Sequenciamento Completo do Exoma
7.
FASEB J ; 35(10): e21927, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34547123

RESUMO

Cone photoreceptors are responsible for the visual acuity and color vision of the human eye. Red/green cone opsin missense mutations N94K, W177R, P307L, R330Q, and G338E have been identified in subjects with congenital blue cone monochromacy or color-vision deficiency. Studies on disease mechanisms due to these cone opsin mutations have been previously carried out exclusively in vitro, and the reported impairments were not always consistent. Here we expressed these mutants via AAV specifically in vivo in M-opsin knockout mouse cones to investigate their subcellular localization, the pathogenic effects on cone structure, function, and cone viability. We show that these mutations alter the M-opsin structure, function, and localization. N94K and W177R mutants appeared to be misfolded since they localized exclusively in cone inner segments and endoplasmic reticulum. In contrast, P307L, R330Q, and G338E mutants were detected predominately in cone outer segments. Expression of R330Q and G338E, but not P307L opsins, also partially restored expression and correct localization of cone PDE6α' and cone transducin γ and resulted in partial rescue of M-cone-mediated light responses. Expression of W177R and P307L mutants significantly reduced cone viability, whereas N94K, R330Q, and G338E were only modestly toxic. We propose that although the underlying biochemical and cellular defects caused by these mutants are distinct, they all seem to exhibit a dominant phenotype, resembling autosomal dominant retinitis pigmentosa associated with the majority of rhodopsin missense mutations. The understanding of the molecular mechanisms associated with these cone opsin mutants is fundamental to developing targeted therapies for cone dystrophy/dysfunction.


Assuntos
Distrofia de Cones/genética , Opsinas dos Cones/genética , Genes Ligados ao Cromossomo X , Mutação de Sentido Incorreto/genética , Animais , Feminino , Humanos , Masculino , Camundongos , Retinite Pigmentosa/genética , Rodopsina/genética , Opsinas de Bastonetes/genética
9.
Pflugers Arch ; 473(9): 1455-1468, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34255151

RESUMO

Light activation of the classical light-sensing retinal neurons, the photoreceptors, results in a graded change in membrane potential that ultimately leads to a reduction in neurotransmitter release to the post-synaptic retinal neurons. Photoreceptors show striking powers of adaptation, and for visual processing to function optimally, they must adjust their gain to remain responsive to different levels of ambient light intensity. The presence of a tightly controlled balance of inward and outward currents modulated by several different types of ion channels is what gives photoreceptors their remarkably dynamic operating range. Part of the resetting and modulation of this operating range is controlled by potassium and calcium voltage-gated channels, which are involved in setting the dark resting potential and synapse signal processing, respectively. Their essential contribution to visual processing is further confirmed in patients suffering from cone dystrophy with supernormal rod response (CDSRR) and congenital stationary night blindness type 2 (CSNB2), both conditions that lead to irreversible vision loss. This review will discuss these two types of voltage-gated ion channels present in photoreceptors, focussing on their structure and physiology, and their role in visual processing. It will also discuss the use and benefits of knockout mouse models to further study the function of these channels and what routes to potential treatments could be applied for CDSRR and CSNB2.


Assuntos
Canais de Cálcio/metabolismo , Distrofia de Cones/metabolismo , Oftalmopatias Hereditárias/metabolismo , Doenças Genéticas Ligadas ao Cromossomo X/metabolismo , Miopia/metabolismo , Cegueira Noturna/metabolismo , Células Fotorreceptoras de Vertebrados/metabolismo , Canais de Potássio de Abertura Dependente da Tensão da Membrana/metabolismo , Animais , Canais de Cálcio/genética , Distrofia de Cones/genética , Oftalmopatias Hereditárias/genética , Doenças Genéticas Ligadas ao Cromossomo X/genética , Humanos , Miopia/genética , Cegueira Noturna/genética , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genética , Retinite Pigmentosa/genética , Retinite Pigmentosa/metabolismo
10.
Int J Mol Sci ; 22(10)2021 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-34065499

RESUMO

Mutations in POC1B are a rare cause of inherited retinal degeneration. In this study, we present a thorough phenotypic and genotypic characterization of three individuals harboring putatively pathogenic variants in the POC1B gene. All patients displayed a similar, slowly progressive retinopathy (cone dystrophy or cone-rod dystrophy) with normal funduscopy but disrupted outer retinal layers on optical coherence tomography and variable age of onset. Other symptoms were decreased visual acuity and photophobia. Whole genome sequencing revealed a novel homozygous frameshift variant in one patient. Another patient was shown to harbor a novel deep intronic variant in compound heterozygous state with a previously reported canonical splice site variant. The third patient showed a novel nonsense variant and a novel non-canonical splice site variant. We aimed to validate the effect of the deep intronic variant and the non-canonical splice site variant by means of in vitro splice assays. In addition, direct RNA analysis was performed in one patient. Splicing analysis revealed that the non-canonical splice site variant c.561-3T>C leads to exon skipping while the novel deep intronic variant c.1033-327T>A causes pseudoexon activation. Our data expand the genetic landscape of POC1B mutations and confirm the benefit of genome sequencing in combination with downstream functional validation using minigene assays for the analysis of putative splice variants. In addition, we provide clinical multimodal phenotyping of the affected individuals.


Assuntos
Proteínas de Ciclo Celular/genética , Distrofia de Cones/genética , Íntrons/genética , Mutação/genética , Sítios de Splice de RNA/genética , Splicing de RNA/genética , Degeneração Retiniana/genética , Adolescente , Adulto , Éxons/genética , Feminino , Células HEK293 , Heterozigoto , Homozigoto , Humanos , Masculino , Retinite Pigmentosa/genética , Virulência/genética , Adulto Jovem
12.
Int J Mol Sci ; 22(8)2021 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-33919796

RESUMO

Guanylate cyclase-activating protein 1 (GCAP1) is involved in the shutdown of the phototransduction cascade by regulating the enzymatic activity of retinal guanylate cyclase via a Ca2+/cGMP negative feedback. While the phototransduction-associated role of GCAP1 in the photoreceptor outer segment is widely established, its implication in synaptic transmission to downstream neurons remains to be clarified. Here, we present clinical and biochemical data on a novel isolate GCAP1 variant leading to a double amino acid substitution (p.N104K and p.G105R) and associated with cone dystrophy (COD) with an unusual phenotype. Severe alterations of the electroretinogram were observed under both scotopic and photopic conditions, with a negative pattern and abnormally attenuated b-wave component. The biochemical and biophysical analysis of the heterologously expressed N104K-G105R variant corroborated by molecular dynamics simulations highlighted a severely compromised Ca2+-sensitivity, accompanied by minor structural and stability alterations. Such differences reflected on the dysregulation of both guanylate cyclase isoforms (RetGC1 and RetGC2), resulting in the constitutive activation of both enzymes at physiological levels of Ca2+. As observed with other GCAP1-associated COD, perturbation of the homeostasis of Ca2+ and cGMP may lead to the toxic accumulation of second messengers, ultimately triggering cell death. However, the abnormal electroretinogram recorded in this patient also suggested that the dysregulation of the GCAP1-cyclase complex further propagates to the synaptic terminal, thereby altering the ON-pathway related to the b-wave generation. In conclusion, the pathological phenotype may rise from a combination of second messengers' accumulation and dysfunctional synaptic communication with bipolar cells, whose molecular mechanisms remain to be clarified.


Assuntos
Cálcio/metabolismo , Distrofia de Cones/genética , Distrofia de Cones/fisiopatologia , Proteínas Ativadoras de Guanilato Ciclase/genética , Mutação/genética , Células Bipolares da Retina/patologia , Células Fotorreceptoras Retinianas Bastonetes/patologia , Transmissão Sináptica , Atrofia , Cátions , Distrofia de Cones/diagnóstico por imagem , Progressão da Doença , Eletrorretinografia , Feminino , Fundo de Olho , Guanilato Ciclase/metabolismo , Proteínas Ativadoras de Guanilato Ciclase/química , Heterozigoto , Humanos , Hidrodinâmica , Interações Hidrofóbicas e Hidrofílicas , Pessoa de Meia-Idade , Simulação de Dinâmica Molecular , Fenótipo , Agregados Proteicos , Estabilidade Proteica , Estrutura Quaternária de Proteína , Células Bipolares da Retina/metabolismo , Epitélio Pigmentado da Retina/patologia , Células Fotorreceptoras Retinianas Bastonetes/metabolismo , Tomografia de Coerência Óptica
13.
Hum Mol Genet ; 30(13): 1218-1229, 2021 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-33891002

RESUMO

Cone dystrophies are a rare subgroup of inherited retinal dystrophies and hallmarked by color vision defects, low or decreasing visual acuity and central vision loss, nystagmus and photophobia. Applying genome-wide linkage analysis and array comparative genome hybridization, we identified a locus for autosomal dominant cone dystrophy on chromosome 16q12 in four independent multigeneration families. The locus is defined by duplications of variable size with a smallest region of overlap of 608 kb affecting the IRXB gene cluster and encompasses the genes IRX5 and IRX6. IRX5 and IRX6 belong to the Iroquois (Iro) protein family of homeodomain-containing transcription factors involved in patterning and regionalization of embryonic tissue in vertebrates, including the eye and the retina. All patients presented with a unique progressive cone dystrophy phenotype hallmarked by early tritanopic color vision defects. We propose that the disease underlies a misregulation of the IRXB gene cluster on chromosome 16q12 and demonstrate that overexpression of Irx5a and Irx6a, the two orthologous genes in zebrafish, results in visual impairment in 5-day-old zebrafish larvae.


Assuntos
Duplicação Cromossômica , Cromossomos Humanos Par 16/genética , Defeitos da Visão Cromática/genética , Distrofia de Cones/genética , Proteínas de Homeodomínio/genética , Família Multigênica , Fatores de Transcrição/genética , Animais , Hibridização Genômica Comparativa/métodos , Saúde da Família , Feminino , Regulação da Expressão Gênica , Genes Dominantes/genética , Humanos , Masculino , Linhagem , Análise de Sequência de DNA/métodos , Peixe-Zebra/genética
14.
Genes (Basel) ; 12(4)2021 03 29.
Artigo em Inglês | MEDLINE | ID: mdl-33805381

RESUMO

Mutations in RPGRORF15 are associated with rod-cone or cone/cone-rod dystrophy, the latter associated with mutations at the distal end. We describe the phenotype associated with a novel variant in the terminal codon of the RPGRORF15 c.3457T>A (Ter1153Lysext*38), which results in a C-terminal extension. Three male patients from two families were recruited, aged 31, 35, and 38 years. Genetic testing was performed by whole exome sequencing. Filtered variants were analysed according to the population frequency, ClinVar database, the variant's putative impact, and predicted pathogenicity; and were classified according to the ACMG guidelines. Examination included visual acuity (Snellen), colour vision (Ishihara), visual field, fundus autofluorescence (FAF), optical coherence tomography (OCT), and electrophysiology. All patients were myopic, and had central scotoma and reduced colour vision. Visual acuities on better eyes were counting fingers, 0.3 and 0.05. Electrophysiology showed severely reduced cone-specific responses and macular dysfunction, while the rod-specific response was normal. FAF showed hyperautofluorescent ring centred at the fovea encompassing an area of photoreceptor loss approximately two optic discs in diameter (3462-6342 µm). Follow up after 2-11 years showed enlargement of the diameter (avg. 100 µm/year). The novel c.3457T>A (Ter1153Lysext*38) mutation in the terminal RPGRORF15 codon is associated with cone dystrophy, which corresponds to the previously described phenotypes associated with mutations in the distal end of the RPGRORF15. Minimal progression during follow-up years suggests a relatively stable disease after the initial loss of the central cones.


Assuntos
Códon , Distrofia de Cones/patologia , Proteínas do Olho/genética , Mutação , Fenótipo , Adulto , Distrofia de Cones/genética , Feminino , Humanos , Masculino , Linhagem
16.
Curr Eye Res ; 46(5): 731-738, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33073619

RESUMO

PURPOSE: To evaluate the efficacy of visual rehabilitation with microperimeter biofeedback in patients with central scotoma. MATERIALS AND METHODS: 35 consecutive patients with central scotoma (17 age-related macular degeneration (AMD), 14 Stargardt disease, and 4 cone dystrophy) were included in the study. Visual acuity, reading performance by Minnesota Low Vision Reading Test (MNREAD), quality of life by 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25), and fixation analysis by MAIA microperimeter were evaluated before and 1 month after training. The rehabilitation program consisted of 10 training sessions of 10 minutes. RESULTS: The median best-corrected visual acuity (BCVA) was 0.80 logMAR (range 0.3 to 1.3 logMAR). Fifty-nine percent of patients with AMD developed a preferred retinal locus (PRL) nasal to the fovea, and 64% of the patients with Stargardt disease preferred a PRL superior to the fovea. The PRL location in 3 of 4 cone dystrophy patients was nasal to the fovea. The mean PRL distance from the fovea was 7.57 ± 3.61 degrees. Fixation stability improved with P1 values of 22.34 ± 11.81 versus 32.05 ± 18.79 (p = .003) and 95% bivariate contour ellipse area (BCEA) values of 41.6 versus 23.6 (p = .018) before and after training, respectively. There was a significant difference in reading acuity between before and after training (p = 0.008). The overall score and near activities score of NEI VFQ-25 were found to be increased at the end of the rehabilitation (p < 0.001). CONCLUSION: Rehabilitation with acoustic biofeedback in patients with central scotoma looks like a useful technique for improving fixation stability, reading performance and quality of life.


Assuntos
Biorretroalimentação Psicológica/métodos , Escotoma/terapia , Baixa Visão/reabilitação , Testes de Campo Visual/métodos , Estimulação Acústica , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Distrofia de Cones/complicações , Feminino , Fixação Ocular/fisiologia , Humanos , Degeneração Macular/complicações , Masculino , Pessoa de Meia-Idade , Leitura , Escotoma/etiologia , Escotoma/fisiopatologia , Doença de Stargardt/complicações , Inquéritos e Questionários , Resultado do Tratamento , Acuidade Visual/fisiologia , Campos Visuais/fisiologia
17.
Invest Ophthalmol Vis Sci ; 61(12): 1, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-33001157

RESUMO

Purpose: Genetic variation in PDE6C is associated with achromatopsia and cone dystrophy, with only a few reports of cone-rod dystrophy in the literature. We describe two pediatric and two adult patients with PDE6C related cone and cone-rod dystrophy and the first longitudinal data of a pediatric patient with PDE6C-related cone dystrophy. Methods: This cohort of four patients underwent comprehensive ophthalmologic evaluation at the National Eye Institute's Ophthalmic Genetics clinic, including visual field testing, retinal imaging and electroretinogram (ERG). Next-generation sequencing-based genetic testing was performed and subsequent analysis of the variants was done through three-dimensional protein models generated by Phyre2 and Chimera. Results: All cases shared decreased best-corrected visual acuity and poor color discrimination. Three of the four patients had a cone-rod dystrophy, presenting with an ERG showing decreased amplitude on both photopic and scotopic waveforms and a mild to moderately constricted visual field. One of the children was diagnosed with cone dystrophy, having a preserved peripheral field. The children had none to minor structural retinal changes, whereas the adults had clear macular dystrophy. Conclusions: PDE6C-related cone-rod dystrophy consists of a severe phenotype characterized by early-onset nystagmus, decreased best-corrected visual acuity, poor color discrimination, progressive constriction of the visual field, and night blindness. Our work contributes with valuable information toward understanding the visual prognosis and allelic heterogeneity of PDE6C-related cone and cone-rod dystrophy.


Assuntos
Defeitos da Visão Cromática/genética , Distrofia de Cones/genética , Distrofias de Cones e Bastonetes/genética , Nucleotídeo Cíclico Fosfodiesterase do Tipo 6/genética , Proteínas do Olho/genética , Mutação , Células Fotorreceptoras Retinianas Cones/patologia , Criança , Defeitos da Visão Cromática/diagnóstico por imagem , Defeitos da Visão Cromática/fisiopatologia , Distrofia de Cones/diagnóstico por imagem , Distrofia de Cones/fisiopatologia , Distrofias de Cones e Bastonetes/diagnóstico por imagem , Distrofias de Cones e Bastonetes/fisiopatologia , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Masculino , Pessoa de Meia-Idade , Linhagem , Fenótipo , Transtornos da Visão/genética , Transtornos da Visão/fisiopatologia , Acuidade Visual/fisiologia , Testes de Campo Visual , Campos Visuais/fisiologia
18.
Cell Death Dis ; 11(8): 631, 2020 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-32801350

RESUMO

Hippo signalling regulates eye growth during embryogenesis through its effectors YAP and TAZ. Taking advantage of a Yap heterozygous mouse line, we here sought to examine its function in adult neural retina, where YAP expression is restricted to Müller glia. We first discovered an unexpected temporal dynamic of gene compensation. At postnatal stages, Taz upregulation occurs, leading to a gain of function-like phenotype characterised by EGFR signalling potentiation and delayed cell-cycle exit of retinal progenitors. In contrast, Yap+/- adult retinas no longer exhibit TAZ-dependent dosage compensation. In this context, Yap haploinsufficiency in aged individuals results in Müller glia dysfunction, late-onset cone degeneration, and reduced cone-mediated visual response. Alteration of glial homeostasis and altered patterns of cone opsins were also observed in Müller cell-specific conditional Yap-knockout aged mice. Together, this study highlights a novel YAP function in Müller cells for the maintenance of retinal tissue homeostasis and the preservation of cone integrity. It also suggests that YAP haploinsufficiency should be considered and explored as a cause of cone dystrophies in human.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas de Ciclo Celular/metabolismo , Distrofia de Cones/patologia , Células Ependimogliais/metabolismo , Células Ependimogliais/patologia , Haploinsuficiência/genética , Animais , Animais Recém-Nascidos , Proteínas de Transporte/metabolismo , Ciclo Celular , Proliferação de Células , Distrofia de Cones/genética , Receptores ErbB/metabolismo , Deleção de Genes , Regulação da Expressão Gênica , Homeostase , Camundongos Knockout , Modelos Biológicos , Opsinas/metabolismo , Fenótipo , Retina/patologia , Células Fotorreceptoras Retinianas Cones/metabolismo , Células Fotorreceptoras Retinianas Cones/patologia , Degeneração Retiniana/genética , Degeneração Retiniana/patologia , Células-Tronco/metabolismo , Transativadores/metabolismo
19.
Int J Mol Sci ; 21(3)2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31979372

RESUMO

Guanylate Cyclase activating protein 1 (GCAP1) mediates the Ca2+-dependent regulation of the retinal Guanylate Cyclase (GC) in photoreceptors, acting as a target inhibitor at high [Ca2+] and as an activator at low [Ca2+]. Recently, a novel missense mutation (G86R) was found in GUCA1A, the gene encoding for GCAP1, in patients diagnosed with cone-rod dystrophy. The G86R substitution was found to affect the flexibility of the hinge region connecting the N- and C-domains of GCAP1, resulting in decreased Ca2+-sensitivity and abnormally enhanced affinity for GC. Based on a structural model of GCAP1, here, we tested the hypothesis of a cation-π interaction between the positively charged R86 and the aromatic W94 as the main mechanism underlying the impaired activator-to-inhibitor conformational change. W94 was mutated to F or L, thus, resulting in the double mutants G86R+W94L/F. The double mutants showed minor structural and stability changes with respect to the single G86R mutant, as well as lower affinity for both Mg2+ and Ca2+, moreover, substitutions of W94 abolished "phase II" in Ca2+-titrations followed by intrinsic fluorescence. Interestingly, the presence of an aromatic residue in position 94 significantly increased the aggregation propensity of Ca2+-loaded GCAP1 variants. Finally, atomistic simulations of all GCAP1 variants in the presence of Ca2+ supported the presence of two cation-π interactions involving R86, which was found to act as a bridge between W94 and W21, thus, locking the hinge region in an activator-like conformation and resulting in the constitutive activation of the target under physiological conditions.


Assuntos
Distrofia de Cones/metabolismo , Proteínas Ativadoras de Guanilato Ciclase/química , Proteínas Ativadoras de Guanilato Ciclase/metabolismo , Guanilato Ciclase/metabolismo , Aminoácidos Aromáticos/química , Cálcio/metabolismo , Cátions/química , Dicroísmo Circular , Distrofia de Cones/genética , Difusão Dinâmica da Luz , Proteínas Ativadoras de Guanilato Ciclase/genética , Células HEK293 , Humanos , Simulação de Dinâmica Molecular , Mutação de Sentido Incorreto , Ligação Proteica , Conformação Proteica , Proteínas Recombinantes , Termodinâmica
20.
Sci Rep ; 9(1): 16851, 2019 11 14.
Artigo em Inglês | MEDLINE | ID: mdl-31728034

RESUMO

GUCA1A gene variants are associated with autosomal dominant (AD) cone dystrophy (COD) and cone-rod dystrophy (CORD). GUCA1A-associated AD-COD/CORD has never been reported in the Japanese population. The purpose of this study was to investigate clinical and genetic features of GUCA1A-associated AD-COD/CORD from a large Japanese cohort. We identified 8 variants [c.C50_80del (p.E17VfsX22), c.T124A (p.F42I), c.C204G (p.D68E), c.C238A (p.L80I), c.T295A (p.Y99N), c.A296C (p.Y99S), c.C451T (p.L151F), and c.A551G (p.Q184R)] in 14 families from our whole exome sequencing database composed of 1385 patients with inherited retinal diseases (IRDs) from 1192 families. Three variants (p.Y99N, p.Y99S, and p.L151F), which are located on/around EF-hand domains 3 and 4, were confirmed as "pathogenic", whereas the other five variants, which did not co-segregate with IRDs, were considered "non-pathogenic". Ophthalmic findings of 9 patients from 3 families with the pathogenic variants showed central visual impairment from early to middle-age onset and progressive macular atrophy. Electroretinography revealed severely decreased or non-recordable cone responses, whereas rod responses were highly variable, ranging from nearly normal to non-recordable. Our results indicate that the three pathogenic variants, two of which were novel, underlie AD-COD/CORD with progressive retinal atrophy, and the prevalence (0.25%, 3/1192 families) of GUCA1A-associated IRDs may be low among Japanese patients.


Assuntos
Distrofia de Cones/genética , Distrofias de Cones e Bastonetes/genética , Proteínas Ativadoras de Guanilato Ciclase/genética , Padrões de Herança , Polimorfismo Genético , Adolescente , Adulto , Idade de Início , Idoso , Sequência de Aminoácidos , Distrofia de Cones/diagnóstico , Distrofia de Cones/epidemiologia , Distrofia de Cones/patologia , Distrofias de Cones e Bastonetes/diagnóstico , Distrofias de Cones e Bastonetes/epidemiologia , Distrofias de Cones e Bastonetes/patologia , Análise Mutacional de DNA , Eletrorretinografia , Feminino , Angiofluoresceinografia , Expressão Gênica , Genes Dominantes , Humanos , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Linhagem , Prevalência , Retina/metabolismo , Retina/patologia , Alinhamento de Sequência
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