Special Issue Introduction: Inherited Retinal Disease: Novel Candidate Genes, Genotype-Phenotype Correlations, and Inheritance Models

Functional Genomics of the Retina to Elucidate its Construction and Deconstruction

The retina is the light sensitive part of the eye and nervous tissue that have been used extensively to characterize the function of the central nervous system. The retina has a central position both in fundamental biology and in the physiopathology of neurodegenerative diseases. We address the contribution of functional genomics to the understanding of retinal biology by reviewing key events in their historical perspective as an introduction to major findings that were obtained through the study of the retina using genomics, transcriptomics and proteomics. We illustrate our purpose by showing that most of the genes of interest for retinal development and those involved in inherited retinal degenerations have a restricted expression to the retina and most particularly to photoreceptors cells. We show that the exponential growth of data generated by functional genomics is a future challenge not only in terms of storage but also in terms of accessibility to the scientific community of retinal biologists in the future. Finally, we emphasize on novel perspectives that emerge from the development of redox-proteomics, the new frontier in retinal biology.

Inherited Retinal Disorders: Using Evidence as a Driver for Implementation

Incremental advances in the field of retinal genetics have transformed our understanding of inherited retinal disorders and have led to the development of powerful diagnostic tests and promising gene-based therapies. Despite this, successful integration of these developments into routine healthcare is frequently ineffective. Providing robust evidence of benefit can accelerate the implementation of clinical genetic interventions. For example, the adoption of a genetic test is much more likely when the test's clinical utility (i.e. its ability to influence management and health outcomes) has been clearly demonstrated. However, accruing such evidence for rare conditions like inherited retinal disorders is challenging. Conducting sufficiently powered studies requires both efficient study designs and large-scale, international collaboration. Reaching all populations and as many affected individuals as possible is key. Equally important are efforts to precisely and consistently capture phenotypic information, including natural history data. This article summarizes some of the current obstacles to implemen-tation and discusses approaches to overcome these barriers.

Genetic and Clinical Findings in a Large Cohort of Chinese Patients with Suspected Retinitis Pigmentosa

PURPOSE

To characterize the genetic landscape of patients with suspected retinitis pigmentosa (RP) in the Chinese population.

DESIGN

Cohort study.

PARTICIPANTS

A total of 1243 patients of Chinese origin with clinically suspected RP and their available family members (n = 2701) were recruited.

METHODS

All patients and available family members were screened using multigene panel testing (including 586 eye disease-associated genes), followed by clinical variant interpretation.

MAIN OUTCOME MEASURES

Diagnostic yield, the 17 most commonly implicated genes, age at onset, de novo mutations, and clinical usefulness of genetic testing.

RESULTS

Overall, 72.08% of patients received a molecular diagnosis, and the 17 top genes covered 75.63% of diagnostic cases. Diagnostic yield was higher among patients in the early-onset subgroup (≤5 years old, 79.58%) than in the childhood or adolescence-onset subgroup (6-16 years old, 73.74%) and late-onset subgroup (≥17 years old, 65.99%). Moreover, different genes associated with different onset ages and subgroups with different onset ages showed a diverse mutation spectrum. Only 11 de novo mutations (3.18%) were identified. Furthermore, 16.84% of the patients who received a molecular diagnosis had refinement of the initial clinical diagnoses, and the remaining 83.16% received definite genetic subtypes of RP.

CONCLUSIONS

This large cohort study provides population-based data of the genome landscape of patients with suspected RP in China. The diagnostic yield was significantly higher than that in previous studies, and the mutation spectrum is completely different with other populations. Genetic testing improves the chance to establish a precise diagnosis, identifies features not previously determined, and allows a more accurate refinement of risk to family members. Our results not only expand the existing genotypic spectrum but also serve as an efficient reference for the design of panel-based genetic diagnostic testing and genetic counseling for patients with suspected RP in China.

Emerging Drug Therapies for Inherited Retinal Dystrophies

Worldwide, 1 in 2000 people suffer from inherited retinal dystrophies (IRD). Individuals with IRD typically present with progressive vision loss that ultimately results in blindness. Unfortunately, effective treatment options are not widely available due to the genetic and clinical heterogeneity of these diseases. There are multiple gene, cell, and drug-based therapies in various phases of clinical trials for IRD. This mini-review documents current progress made in drug-based clinical trials for treating IRD.

Progress in Inherited Retinal Disease Drug Discovery and Development: A Foundation's Perspective

Ophthalmic drug discovery and development has enjoyed a recent renaissance, with a major shift away from reformulating old systemic drugs for ocular use to de novo discovery of drugs for specific ocular disease targets. This shift, coupled with a revolution in molecular biology and genetic sequencing, has uncovered an unprecedented number and variety of novel targets for therapeutic intervention in eye disease. With such a treasure chest of new science to pursue, it also creates a new challenge for translating the lab-based discoveries through the translational "valley of death" into full scale industry-led development of new, approved therapeutics to treat eye disease. This is in fact a daunting task, as the cost of drug development continues to increase and many of the new therapeutic targets are based on smaller, orphan diseases with very high unmet medical needs. This perspective focuses on the role of a nonprofit foundation, The Foundation Fighting Blindness, in fueling and supporting the advancement of new therapies for blinding inherited retinal degenerative diseases into approved therapeutics. The new collaborative model is changing the way breakthrough drugs are coming to market for patients, and innovative funding models are required to match the innovative science.