Advances in retina genetics: Progress, potential, and challenges

State of the Art on Inherited Retinal Dystrophies: Management and Molecular Genetics

Inherited retinal dystrophies (IRDs) represent a group of heterogeneous disorders caused by gene mutations primarily affecting retinal photoreceptors. In addition to vision loss, other symptoms may lead to visual impairment, such as altered visual fields, hemeralopia, glare sensitivity, and impaired color vision. These conditions almost always complicate with the onset of cataracts, macular edema or atrophy, glaucoma, etc. A brief overview of key genes involved in the most common and well-known IRDs is provided, followed by clinical and diagnostic implications. The study of IRDs has seen a significant acceleration in recent decades, owing to advances in molecular genetics with the introduction of exome sequencing (WES) and genome-wide association studies (GWASs), which have facilitated the identification of a broad spectrum of genes associated with IRDs. This has led to the classification of five genetic variants, based on the criteria of the American College of Medical Genetics and Genomics (ACMG), serving as a guide for interpreting genetic reports. Next, approaches to genomic editing therapies and research directions regarding artificial intelligence (AI) and machine learning (ML) are discussed. The paper concludes with an examination of the inevitable ethical and regulatory issues, typically driven by regulatory bodies such as the Food and Drug Administration (FDA).

Keep an Eye on Next Generation Sequencing (NGS) Technology: Secondary Findings and Differential Diagnosis in Inherited Retinal Dystrophies (IRDs)

Background: Next Generation Sequencing (NGS) Technology has represented a revolution in the molecular characterization of Inherited Retinal Dystrophies (IRDs), which are among the most genetically and phenotypically heterogeneous conditions. NGS has allowed the characterization of a consistent number of patients affected by IRDs, but at the same time, unexpected results can pose diagnostic dilemmas. Aim: The purpose of this review is to describe possible scenarios as a reference for ophthalmologists and geneticists who are involved in this particularly complex field. Methods: A review of the existing literature has been performed. In addition, examples have been brought, from a series of patients that have been analyzed at the University of Naples "Federico II"-CEINGE Biotecnologie Avanzate "Franco Salvatore". Results: Unexpected results in the genetic characterization of IRDs are not uncommon. The main findings are additional variants that potentially modify phenotypes, deletions masked by apparent homozygosity, and pathogenic variants leading to phenotypes revisitation. Conclusions: The high genetic and phenotypic heterogeneity characterizing IRDs have been greatly advantaged by the advent of NGS Technology. At the same time, the not uncommon finding of unexpected data poses diagnostic criticisms that need to be addressed. In this review, we describe possible scenarios, and we go through some more complex genotype-phenotype correlations.