AUTOIMMUNE RETINOPATHY MIMICKING HERITABLE RETINAL DEGENERATION IN A PATIENT WITH COMMON VARIABLE IMMUNE DEFICIENCY

Retinitis Pigmentosa Masquerades: Case Series and Review of the Literature

Retinitis pigmentosa (RP) displays a broad range of phenotypic variations, often overlapping with acquired retinal diseases. Timely recognition and differentiation of RP masquerades is paramount due to the treatable nature of many such conditions. This review seeks to present examples of pseudo-RP cases and provide a comprehensive overview of RP masquerades. We first present two pseudo-RP cases, including comprehensive clinical histories and multimodal retinal imaging, to highlight the important role of accurate diagnoses that subsequently steered effective intervention. Subsequently, we conduct an in-depth review of RP masquerades to provide valuable insights into their key distinguishing features and management considerations. The recent approval of ocular gene therapy and the development of investigational gene-based treatments have brought genetic testing to the forefront for RP patients. However, it is important to note that genetic testing currently lacks utility as a screening tool for inherited retinal diseases (IRDs), including RP. The integrity of a precise clinical assessment remains indispensable for the diagnosis of both RP and RP masquerade conditions, thereby facilitating prompt intervention and appropriate management strategies.

Patient derived stem cells for discovery and validation of novel pathogenic variants in inherited retinal disease

Our understanding of inherited retinal disease has benefited immensely from molecular genetic analysis over the past several decades. New technologies that allow for increasingly detailed examination of a patient's DNA have expanded the catalog of genes and specific variants that cause retinal disease. In turn, the identification of pathogenic variants has allowed the development of gene therapies and low-cost, clinically focused genetic testing. Despite this progress, a relatively large fraction (at least 20%) of patients with clinical features suggestive of an inherited retinal disease still do not have a molecular diagnosis today. Variants that are not obviously disruptive to the codon sequence of exons can be difficult to distinguish from the background of benign human genetic variations. Some of these variants exert their pathogenic effect not by altering the primary amino acid sequence, but by modulating gene expression, isoform splicing, or other transcript-level mechanisms. While not discoverable by DNA sequencing methods alone, these variants are excellent targets for studies of the retinal transcriptome. In this review, we present an overview of the current state of pathogenic variant discovery in retinal disease and identify some of the remaining barriers. We also explore the utility of new technologies, specifically patient-derived induced pluripotent stem cell (iPSC)-based modeling, in further expanding the catalog of disease-causing variants using transcriptome-focused methods. Finally, we outline bioinformatic analysis techniques that will allow this new method of variant discovery in retinal disease. As the knowledge gleaned from previous technologies is informing targets for therapies today, we believe that integrating new technologies, such as iPSC-based modeling, into the molecular diagnosis pipeline will enable a new wave of variant discovery and expanded treatment of inherited retinal disease.