RESUMEN
PURPOSE: Progressive inherited retinal degenerations (IRDs) affecting rods and cones are clinically and genetically heterogeneous and can lead to blindness with limited therapeutic options. The major gene defects have been identified in subjects of European and Asian descent with only few reports of North African descent. METHODS: Genome, targeted next-generation, and Sanger sequencing was applied to cohort of â¼4000 IRDs cases. Expression analyses were performed including Chip-seq database analyses, on human-derived retinal organoids (ROs), retinal pigment epithelium cells, and zebrafish. Variants' pathogenicity was accessed using 3D-modeling and/or ROs. RESULTS: Here, we identified a novel gene defect with three distinct pathogenic variants in UBAP1L in 4 independent autosomal recessive IRD cases from Tunisia. UBAP1L is expressed in the retinal pigment epithelium and retina, specifically in rods and cones, in line with the phenotype. It encodes Ubiquitin-associated protein 1-like, containing a solenoid of overlapping ubiquitin-associated domain, predicted to interact with ubiquitin. In silico and in vitro studies, including 3D-modeling and ROs revealed that the solenoid of overlapping ubiquitin-associated domain is truncated and thus ubiquitin binding most likely abolished secondary to all variants identified herein. CONCLUSION: Biallelic UBAP1L variants are a novel cause of IRDs, most likely enriched in the North African population.
Asunto(s)
Distrofias de Conos y Bastones , Linaje , Pez Cebra , Humanos , Distrofias de Conos y Bastones/genética , Distrofias de Conos y Bastones/patología , Masculino , Femenino , Pez Cebra/genética , Animales , Genes Recesivos , Epitelio Pigmentado de la Retina/metabolismo , Epitelio Pigmentado de la Retina/patología , Mutación/genética , Células Fotorreceptoras Retinianas Conos/patología , Células Fotorreceptoras Retinianas Conos/metabolismo , Retina/patología , Retina/metabolismo , Adulto , Túnez , Retinitis Pigmentosa/genética , Retinitis Pigmentosa/patología , Fenotipo , Células Fotorreceptoras Retinianas Bastones/metabolismo , Células Fotorreceptoras Retinianas Bastones/patologíaRESUMEN
The ITM2B-related retinal dystrophy (ITM2B-RD) was identified within patients carrying the autosomal dominant variant [c.782A > C, p.(Glu261Ala)] in ITM2B from whom induced pluripotent stem cell (IPSC) lines were previously generated. Here, we report the generation of three isogenic control iPSC lines from the derived affected subject cell line (ITM2B-5286-3) using CRISPR/Cas9 engineering. The three generated lines express pluripotency markers, can be differentiated into the three germ layers and present a normal karyotype. The generated iPSC lines can be used to study the implications of ITM2B-RD variant in vitro.
Asunto(s)
Células Madre Pluripotentes Inducidas , Distrofias Retinianas , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Sistemas CRISPR-Cas/genética , Distrofias Retinianas/genética , Distrofias Retinianas/metabolismo , Diferenciación Celular , Mutación , Proteínas Adaptadoras Transductoras de Señales/genéticaRESUMEN
PURPOSE: To reappraise the presentation and the course of ITM2B-related retinal dystrophy and give further insights into ITM2B expression in the retina. METHODS: The clinical data of nine subjects with ITM2B-related retinal dystrophy were retrospectively reviewed. The genetic mutation was assessed for its influence on splicing in cultured fibroblasts. The cellular expression of ITM2B within the inner retina was investigated in wild-type mice through mRNA in situ hybridization. RESULTS: All patients complained of decreased vision and mild photophobia around their twenties-thirties. The peculiar feature was the hyperreflective material on optical coherence tomography within the inner retina and the central outer nuclear layer with thinning of the retinal nerve fiber layer. Although retinal imaging revealed very mild or no changes over the years, the visual acuity slowly decreased with about one Early Treatment Diabetic Retinopathy Study letter per year. Finally, full-field electroretinography showed a mildly progressive inner retinal and cone dysfunction. ITM2B mRNA is expressed in all cellular types of the inner retina. Disease mechanism most likely involves mutant protein misfolding and/or modified protein interaction rather than misplicing. CONCLUSION: ITM2B-related retinal dystrophy is a peculiar, rare, slowly progressive retinal degeneration. Functional examinations (full-field electroretinography and visual acuity) seem more accurate in monitoring the progression in these patients because imaging tends to be stable over the years.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/genética , Distrofias Retinianas/genética , Anciano , Animales , Modelos Animales de Enfermedad , Electrorretinografía , Femenino , Regulación de la Expresión Génica/fisiología , Humanos , Hibridación in Situ , Masculino , Ratones , Ratones Endogámicos C57BL , Persona de Mediana Edad , Imagen Óptica , Fenotipo , ARN Mensajero/genética , Retina/fisiopatología , Distrofias Retinianas/diagnóstico por imagen , Distrofias Retinianas/fisiopatología , Estudios Retrospectivos , Tomografía de Coherencia Óptica , Agudeza Visual/fisiologíaRESUMEN
Human induced pluripotent stem cell (iPSC) lines were generated from fibroblasts of a patient affected with an autosomal dominant retinal dystrophy carrying the mutation c.782A>C, p.Glu261Ala in ITM2B and from an unaffected brother. Three different iPSC lines were generated and characterized from primary dermal fibroblasts of the affected subject and two from the unaffected brother. All iPSC lines expressed the pluripotency markers, were able to differentiate into the three germ layers and presented normal karyotypes. This cellular model will provide a powerful tool to study this retinal dystrophy and better understand the role of ITM2B.
