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Inherited retinal diseases (IRDs) are a leading cause of genetic vision loss, yet they remain difficult to identify and diagnose. Genetic testing plays a pivotal role in identifying the underlying causes, opening the door to timely treatment and improved patient outcomes. Here, we explore key barriers to diagnosing IRDs and the importance of early genetic screening in managing these rare conditions.
Identifying rare disease patients
Although IRDs are one of the leading causes of genetic vision loss, these conditions are still rare and difficult to identify in a population-scale context. Additionally, IRDs often progress slowly and have overlapping symptoms, making them difficult to diagnose and impeding efforts to enroll patients into relevant registries and clinical trials. These conditions are also highly heterogeneous and linked to variants in more than 280 genes, making genetic testing important in identifying the underlying cause, in turn increasing the cost of diagnosing patients.
Barriers to genetic screening
Patient access to genetic testing is an additional challenge, as the cost of testing can pose a significant barrier to gathering the data required for an accurate IRD diagnosis - especially when screening for specific conditions requires a specialized genetic panel. In many healthcare systems, insurance or public health programs may not cover the cost of a genetic test, making access to an accurate IRD diagnosis prohibitive before even reaching the treatment and management stage.
Limited access to genetic services such as testing facilities and genetic counseling also pose a challenge - particularly in rural or underserved regions - making it difficult or potentially impossible for patients to receive the relevant referrals or support. Even in well-served regions, a paucity of trained specialists such as genetic counselors can cause long wait times and reduced accessibility to screening services.
Many healthcare practitioners are also unaware of the need for genetic testing to diagnose IRDs, leading to underdiagnosis and under referral to genetic testing services. However, as awareness and education around personalized medicine increases, it is hoped that genetic testing will be perceived as a standard approach for diagnosing a growing number of conditions.
Screening techniques
With the advent of new technologies such as Next Generation Sequencing (NGS) (including Whole Exome Sequencing) it’s now possible to identify the relevant genetic variants present in up to 70% of IRD cases. Whole Exome Sequencing scans only 1-2% of the entire genome but covers the area which contains 85% of all known disease-causing variants, making it a more cost-effective approach.
However, there are still limitations to genetic testing for IRDs. In 30-40% of cases, the genetic cause remains unclear. Reasons for this high number of undetermined causes include the presence of IRD-linked variants which are undetectable or uninterpretable using NGS.
Importance of early diagnosis
An early diagnosis is fundamental to successful disease management and ensuring the most effective treatment options can be implemented where available. It also enables healthcare professionals to better predict a patient's vision loss journey and what can be done to best support them, again reinforcing the importance of genetic testing in delivering an accurate diagnosis.
Genetic testing is an effective method for enabling early diagnosis and identifying the specific disease causing variants which are present in individual cases, ultimately enabling better care and vision outcomes. In some cases, genetic screening enables patients to get access to gene therapies, as well as opportunities to join relevant clinical trials.
As awareness of personalized medicine increases, genetic testing is poised to become a standard part of diagnosing IRDs, leading to better care and outcomes for patients facing vision loss. To learn more, download our whitepaper:
