The Institute for Vision Research, University of Iowa, Iowa City, IA, USA; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
The Institute for Vision Research, University of Iowa, Iowa City, IA, USA; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
Prog Retin Eye Res. 2021 Jul;83:100918. doi: 10.1016/j.preteyeres.2020.100918. Epub 2020 Oct 29.
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.
在过去的几十年中，分子遗传学分析极大地促进了我们对遗传性视网膜疾病的理解。允许对患者 DNA 进行越来越详细检查的新技术扩展了导致视网膜疾病的基因和特定变体目录。反过来，致病变体的鉴定允许开发基因疗法和低成本、临床重点的基因测试。尽管取得了这一进展，但今天仍有相当一部分（至少 20%）具有遗传性视网膜疾病临床特征的患者尚未获得分子诊断。那些对外显子的密码子序列没有明显破坏的变体可能难以与良性人类遗传变异的背景区分开来。这些变体中的一些不是通过改变主要氨基酸序列，而是通过调节基因表达、异构体剪接或其他转录水平机制来发挥其致病作用。虽然不能仅通过 DNA 测序方法发现这些变体，但它们是视网膜转录组研究的绝佳目标。在这篇综述中，我们介绍了视网膜疾病中致病变体发现的当前状态，并确定了一些尚存的障碍。我们还探讨了新技术的实用性，特别是基于患者来源的诱导多能干细胞 (iPSC) 的建模，如何使用转录组为重点的方法进一步扩展致病变体目录。最后，我们概述了允许在视网膜疾病中发现新变体的生物信息学分析技术。随着从以前的技术中获得的知识为今天的治疗目标提供信息，我们相信将基于 iPSC 的建模等新技术集成到分子诊断管道中，将能够发现新一波的变体，并扩大遗传性视网膜疾病的治疗范围。
