Inherited retinal diseases: How genetic testing is reshaping eye care

Conventional eye exams may not always distinguish one IRD from another, as symptoms like reduced night vision or gradual sight loss are common across several conditions (Image: Canva)

Inherited retinal diseases (IRDs) refer to a broad group of conditions affecting the retina, the light-sensitive tissue at the back of the eye, which can lead to visual impairment or loss. These conditions include retinitis pigmentosa (RP), Stargardt disease, cone-rod dystrophy, and Leber congenital amaurosis (LCA), among others. Onset can vary from infancy to adulthood, and symptoms often overlap, making clinical diagnosis difficult.

Over 200 genes have been associated with IRDs, shares Dr N Soumittra, Disease Head, Ophthalmology, MedGenome. “Many different genes can lead to the same condition, and a single gene can sometimes be linked to multiple forms of IRD. This complexity makes genetic testing a valuable tool in arriving at a more definitive diagnosis,” he says.

Dr. Soumittra outlines the role of genetic testing in the diagnosis and management of inherited retinal diseases:

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• Early and accurate diagnosis: Conventional eye exams may not always distinguish one IRD from another, as symptoms like reduced night vision or gradual sight loss are common across several conditions. Genetic testing can identify the precise mutation involved, supporting an earlier and more accurate diagnosis.

• Predicting disease progression: The course of IRDs can vary widely. Some appear in infancy, while others may not present until later childhood or adolescence. “Knowing the genetic root of the disease enables doctors to estimate how it might progress, whether it starts at birth or shows up in adulthood,” says Dr Soumittra. This information can help patients and clinicians make more informed decisions about ongoing care and monitoring.

• Informing treatment possibilities: While there is currently no universal treatment for IRDs, gene-based therapies are being explored in clinical and research settings. A therapy targeting RPE65 gene mutations is already in use in some countries. Where such treatments are available, genetic testing is essential to determine patient eligibility.

• Supporting family planning: Genetic testing can provide clarity for people regarding carrier status. “This information can help families assess the likelihood of passing on an inherited condition and consider their reproductive options accordingly,” Dr Soumittra notes.

• Identifying syndromic IRDs: Some inherited retinal diseases are part of wider syndromes that affect multiple systems in the body, such as hearing, kidney function, or neurological development. Early genetic testing can help identify these cases, allowing for a more comprehensive approach to care.

• Contributing to research: Each genetic test result contributes to broader research efforts. “The genetic data collected is crucial for developing therapies like gene editing and RNA-based interventions,” adds Dr Soumittra. These insights help build a deeper understanding of IRDs and inform future treatment strategies.