RESUMEN
PURPOSE: In this study, we described a large family presenting different manifestations of cone dystrophy at different ages associated with GUCY2D gene mutation. METHOD: Sixty-three individuals of a single kindred, including 23 affected with cone dystrophies, were recruited and received ocular examinations, including best corrected visual acuity, intraocular pressure, slit-lamp biomicroscopy, color fundus photograph (CFP), fundus autofluorescence, optical coherence tomography, fluorescence fundus angiography, color vision testing, full-field electroretinography, and electro-oculogram. Whole exome sequencing (WES) and Sanger sequencing were performed for underlying mutations associated with cone dystrophy. RESULT: There were 23 affected family members. Clinical analysis showed that the proband and other patients had impaired visual acuity ranging from 20/800 to 20/50 with impaired color vision. Fundus photograph showed retinal pigment epithelium (RPE) granular abnormalities with depressed macular reflex in young patients and macular or retinochoriodal atrophy in older patients. OCT examination confirmed the reduced outer retinal thickness or inner retinal thickness, absence of the ellipsoid zone (EZ) and retinal atrophy to varying degrees. Electroretinography revealed a reduced cone response combined with a relatively maintained rod response. WES and Sanger sequencing revealed a heterozygous variant c.2512C>T in the GUCY2D gene of the affected family members. CONCLUSIONS: We reported cone dystrophy in 23 affected individuals in a five-generation family and demonstrated different macular abnormalities in OCT scans and CFP at different ages. The multimodal ocular records in our study provide physicians and ophthalmologists with a better understanding of cone dystrophy associated with GUCY2D mutation.
Asunto(s)
Distrofia del Cono , Degeneración Retiniana , Humanos , Anciano , Distrofia del Cono/patología , Degeneración Retiniana/diagnóstico , Células Fotorreceptoras Retinianas Conos , Mutación , Electrorretinografía , Atrofia/patología , Tomografía de Coherencia Óptica , Linaje , FenotipoRESUMEN
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.
Asunto(s)
Distrofia del Cono , Distrofias de Conos y Bastones , Transportadoras de Casetes de Unión a ATP/genética , Distrofia del Cono/patología , Distrofias de Conos y Bastones/diagnóstico , Distrofias de Conos y Bastones/genética , Distrofias de Conos y Bastones/patología , Electrorretinografía , Femenino , Angiografía con Fluoresceína , Humanos , Imagen Multimodal , Mutación , Fenotipo , Células Fotorreceptoras Retinianas Conos/patología , Tomografía de Coherencia Óptica/métodosRESUMEN
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.
Asunto(s)
Distrofia del Cono/patología , GMP Cíclico/metabolismo , Proteínas Activadoras de la Guanilato-Ciclasa/genética , Guanilato Ciclasa/metabolismo , Mutación , Retina/enzimología , Células Fotorreceptoras Retinianas Bastones/metabolismo , Adolescente , Calcio/metabolismo , Niño , Distrofia del Cono/genética , Distrofia del Cono/metabolismo , Femenino , Humanos , Fototransducción , Masculino , Persona de Mediana Edad , Linaje , Transducción de SeñalRESUMEN
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.
Asunto(s)
Codón , Distrofia del Cono/patología , Proteínas del Ojo/genética , Mutación , Fenotipo , Adulto , Distrofia del Cono/genética , Femenino , Humanos , Masculino , LinajeRESUMEN
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.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Proteínas de Ciclo Celular/metabolismo , Distrofia del Cono/patología , Células Ependimogliales/metabolismo , Células Ependimogliales/patología , Haploinsuficiencia/genética , Animales , Animales Recién Nacidos , Proteínas Portadoras/metabolismo , Ciclo Celular , Proliferación Celular , Distrofia del Cono/genética , Receptores ErbB/metabolismo , Eliminación de Gen , Regulación de la Expresión Génica , Homeostasis , Ratones Noqueados , Modelos Biológicos , Opsinas/metabolismo , Fenotipo , Retina/patología , Células Fotorreceptoras Retinianas Conos/metabolismo , Células Fotorreceptoras Retinianas Conos/patología , Degeneración Retiniana/genética , Degeneración Retiniana/patología , Células Madre/metabolismo , Transactivadores/metabolismo , Proteínas Señalizadoras YAPRESUMEN
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.
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Distrofia del Cono/genética , Distrofias de Conos y Bastones/genética , Proteínas Activadoras de la Guanilato-Ciclasa/genética , Patrón de Herencia , Polimorfismo Genético , Adolescente , Adulto , Edad de Inicio , Anciano , Secuencia de Aminoácidos , Distrofia del Cono/diagnóstico , Distrofia del Cono/epidemiología , Distrofia del Cono/patología , Distrofias de Conos y Bastones/diagnóstico , Distrofias de Conos y Bastones/epidemiología , Distrofias de Conos y Bastones/patología , Análisis Mutacional de ADN , Electrorretinografía , Femenino , Angiografía con Fluoresceína , Expresión Génica , Genes Dominantes , Humanos , Japón/epidemiología , Masculino , Persona de Mediana Edad , Linaje , Prevalencia , Retina/metabolismo , Retina/patología , Alineación de SecuenciaRESUMEN
Mutations in the KCNV2 gene, which encodes the voltage-gated K+ channel protein Kv8.2, cause a distinctive form of cone dystrophy with a supernormal rod response (CDSRR). Kv8.2 channel subunits only form functional channels when combined in a heterotetramer with Kv2.1 subunits encoded by the KCNB1 gene. The CDSRR disease phenotype indicates that photoreceptor adaptation is disrupted. The electroretinogram (ERG) response of affected individuals shows depressed rod and cone activity, but what distinguishes this disease is the supernormal rod response to a bright flash of light. Here, we have utilized knock-out mutations of both genes in the mouse to study the pathophysiology of CDSRR. The Kv8.2 knock-out (KO) mice show many similarities to the human disorder, including a depressed a-wave and an elevated b-wave response with bright light stimulation. Optical coherence tomography (OCT) imaging and immunohistochemistry indicate that the changes in six-month-old Kv8.2 KO retinae are largely limited to the outer nuclear layer (ONL), while outer segments appear intact. In addition, there is a significant increase in TUNEL-positive cells throughout the retina. The Kv2.1 KO and double KO mice also show a severely depressed a-wave, but the elevated b-wave response is absent. Interestingly, in all three KO genotypes, the c-wave is totally absent. The differential response shown here of these KO lines, that either possess homomeric channels or lack channels completely, has provided further insights into the role of K+ channels in the generation of the a-, b-, and c-wave components of the ERG.
Asunto(s)
Distrofia del Cono/metabolismo , Canales de Potasio con Entrada de Voltaje/metabolismo , Retina/metabolismo , Canales de Potasio Shab/metabolismo , Animales , Distrofia del Cono/diagnóstico por imagen , Distrofia del Cono/patología , Femenino , Técnicas de Inactivación de Genes , Ratones Endogámicos C57BL , Ratones Noqueados , Mutación , Canales de Potasio con Entrada de Voltaje/genética , Retina/diagnóstico por imagen , Retina/patología , Canales de Potasio Shab/genética , Transmisión Sináptica , Visión Ocular/fisiologíaRESUMEN
Inherited retinal degenerations are a common cause of untreatable blindness worldwide, with retinitis pigmentosa and cone dystrophy affecting approximately 1 in 3500 and 1 in 10,000 individuals, respectively. A major limitation to the development of effective therapies is the lack of availability of animal models that fully replicate the human condition. Particularly for cone disorders, rodent, canine, and feline models with no true macula have substantive limitations. By contrast, the cone-rich macula of a nonhuman primate (NHP) closely mirrors that of the human retina. Consequently, well-defined NHP models of heritable retinal diseases, particularly cone disorders that are predictive of human conditions, are necessary to more efficiently advance new therapies for patients. We have identified 4 related NHPs at the California National Primate Research Center with visual impairment and findings from clinical ophthalmic examination, advanced retinal imaging, and electrophysiology consistent with achromatopsia. Genetic sequencing confirmed a homozygous R565Q missense mutation in the catalytic domain of PDE6C, a cone-specific phototransduction enzyme associated with achromatopsia in humans. Biochemical studies demonstrate that the mutant mRNA is translated into a stable protein that displays normal cellular localization but is unable to hydrolyze cyclic GMP (cGMP). This NHP model of a cone disorder will not only serve as a therapeutic testing ground for achromatopsia gene replacement, but also for optimization of gene editing in the macula and of cone cell replacement in general.
Asunto(s)
Distrofia del Cono , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 6 , Modelos Animales de Enfermedad , Proteínas del Ojo , Mutación Missense , Retinitis Pigmentosa , Sustitución de Aminoácidos , Animales , Defectos de la Visión Cromática/enzimología , Defectos de la Visión Cromática/genética , Defectos de la Visión Cromática/patología , Distrofia del Cono/enzimología , Distrofia del Cono/genética , Distrofia del Cono/patología , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 6/genética , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 6/metabolismo , Proteínas del Ojo/genética , Proteínas del Ojo/metabolismo , Femenino , Células HEK293 , Humanos , Macaca mulatta , Masculino , Retinitis Pigmentosa/enzimología , Retinitis Pigmentosa/genética , Retinitis Pigmentosa/patologíaRESUMEN
MicroRNAs (miRNAs) are key post-transcriptional regulators of gene expression that play an important role in the control of fundamental biological processes in both physiological and pathological conditions. Their function in retinal cells is just beginning to be elucidated, and a few have been found to play a role in photoreceptor maintenance and function. MiR-211 is one of the most abundant miRNAs in the developing and adult eye. However, its role in controlling vertebrate visual system development, maintenance and function so far remain incompletely unexplored. Here, by targeted inactivation in a mouse model, we identify a critical role of miR-211 in cone photoreceptor function and survival. MiR-211 knockout (-/-) mice exhibited a progressive cone dystrophy accompanied by significant alterations in visual function. Transcriptome analysis of the retina from miR-211-/- mice during cone degeneration revealed significant alteration of pathways related to cell metabolism. Collectively, this study highlights for the first time the impact of miR-211 function in the retina and significantly contributes to unravelling the role of specific miRNAs in cone photoreceptor function and survival.