Frequency of <i>RPE65</i> Gene Mutation in Patients with Hereditary Retinal Dystrophy

Genetics and phenotypes of RPE65 mutations in inherited retinal degeneration: A study from a tertiary eye care center in Brazil

Purpose

Biallelic variants in the retinal pigment epithelium-specific 65-kDa protein (RPE65) gene are linked to several inherited retinal diseases (IRDs), including Leber congenital amaurosis (LCA), early-onset severe retinal dystrophy (EOSRD), and retinitis pigmentosa (RP). This study screened patients from a tertiary center in Brazil with IRDs for RPE65 variants to characterize the associated phenotypes.

Methods

LCA, EOSRD, and RP diagnoses were based on predefined clinical criteria. Patients underwent comprehensive clinical evaluations and retinal imaging. Genomic DNA was analyzed using a next-generation sequencing panel for IRDs, covering 238 genes.

Results

RPE65 variants were identified in seven of the 68 patients screened. Of these, three were homozygous, and four were compound heterozygous for the identified mutant alleles. A total of six variants were detected, of which one was novel. The p.Leu341Ser (c.1022T>C) mutation was the most prevalent, being found in four of seven patients. Visual loss onset ranged from birth to the third decade of life. A consistent clinical feature observed in all patients was some degree of pigmentary change upon peripheral retinal examination.

Conclusions

RPE65 variants were found in 10.3% of cases in this series, associated with LCA, EOSRD, and RP. These variants were consistently linked with pigmentary changes in the peripheral retina and exhibited variable manifestations regarding arteriolar attenuation, disc pallor, and macular appearance. In this series, the prevalence of the p.Leu341Ser (c.1022T>C) mutation was 57%.

Beyond the phenotype: Exploring inherited retinal diseases with targeted next-generation sequencing in a Turkish cohort

This research aims to compile recent clinical and genetic data from Turkish patients with inherited retinal disorders and evaluate the effectiveness of targeted Next-generation sequencing panels. The study included Turkish individuals with hereditary retinal diseases who visited the Medical Genetic Department of Erciyes University between 2019 and 2022. One proband per family was selected based on eligibility. We used Hereditary Disorder Solution (HDS) by Sophia Genetics and performed next-generation sequencing (NGS) with Illumina NextSeq-500. Bioinformatics analysis using Sophia DDM® SaaS algorithms and ACMG guidelines classified genomic changes. The study involved 354 probands. Disease-causing variants were found in 58.1% of patients, with ABCA4, USH2A, RDH12, and EYS being the most frequently implicated genes. Forty-eight novel variants were detected. This study enhances the knowledge of clinical diagnoses, symptom onset, inheritance patterns, and genetic details for Turkish individuals with hereditary retinal disease. It contributes to broader health strategies by enabling comparisons with other studies.

Adeno-associated virus vectors for retinal gene therapy in basic research and clinical studies

Retinal degenerative diseases, including glaucoma, age-related macular degeneration, diabetic retinopathy, and a broad range of inherited retinal diseases, are leading causes of irreversible vision loss and blindness. Gene therapy is a promising and fast-growing strategy to treat both monogenic and multifactorial retinal disorders. Vectors for gene delivery are crucial for efficient and specific transfer of therapeutic gene(s) into target cells. AAV vectors are ideal for retinal gene therapy due to their inherent advantages in safety, gene expression stability, and amenability for directional engineering. The eye is a highly compartmentalized organ composed of multiple disease-related cell types. To determine a suitable AAV vector for a specific cell type, the route of administration and choice of AAV variant must be considered together. Here, we provide a brief overview of AAV vectors for gene transfer into important ocular cell types, including retinal pigment epithelium cells, photoreceptors, retinal ganglion cells, Müller glial cells, ciliary epithelial cells, trabecular meshwork cells, vascular endothelial cells, and pericytes, via distinct injection methods. By listing suitable AAV vectors in basic research and (pre)clinical studies, we aim to highlight the progress and unmet needs of AAV vectors in retinal gene therapy.