How do Inherited Retinal Diseases Happen?

The Genetics of Vision: Understanding Inherited Retinal Diseases

Inherited Retinal Diseases (IRDs) are a group of rare, progressive eye disorders that are caused by variations in our DNA, leading to severe vision impairment or blindness. While they can manifest at any age, they collectively represent a significant cause of vision loss, often beginning in childhood or early adulthood.

How Do Inherited Retinal Diseases Happen?

The root cause of all IRDs lies in our genes. Genes act as the blueprints for producing proteins that maintain the health and function of every cell in our body, including the specialized cells in the retina.

1. The Role of Genes: The retina, the light-sensitive tissue at the back of the eye, contains millions of light-sensing cells called photoreceptors (rods for night and peripheral vision, and cones for day and color vision). Over 300 different genes have been identified that are vital for the development, survival, and proper function of these retinal cells.

2. Genetic Variants (Mutations): An IRD develops when there is a change—or pathogenic variant—in one of these critical retinal genes. This variant can be inherited from one or both parents, or in some rare cases, occur spontaneously.

3. Protein Dysfunction: This genetic error prevents the gene from producing its required protein correctly. For example, the protein might be:

   • Defective or Missing: It fails to perform its essential job, such as converting light into electrical signals (a process called phototransduction) or recycling key visual molecules.

   • Toxic: It may be produced in a misfolded way that stresses and damages the retinal cell.

4. Cell Degeneration: Over time, the dysfunction caused by the faulty protein leads to the progressive degeneration and death of the rods and/or cones. The type of cell primarily affected determines the specific IRD phenotype (e.g., loss of night vision first in Retinitis Pigmentosa, or loss of central vision in Stargardt disease).

Common Types of IRDs:

• Retinitis Pigmentosa (RP): A group of disorders often causing night blindness first, followed by loss of peripheral vision (tunnel vision).

• Stargardt Disease: Typically affects the macula, leading to a loss of central, sharp vision.

• Leber Congenital Amaurosis (LCA): A severe form that causes vision loss starting in infancy or early childhood.

The Importance of Genetic Testing

For individuals affected by IRDs, genetic testing is a crucial step. Identifying the specific mutated gene provides:

• A definitive diagnosis and a clearer understanding of the disease prognosis.

• A basis for genetic counseling to understand the risk for other family members.

• The eligibility information needed to participate in potential gene therapy clinical trials or access FDA-approved gene therapies like Luxturna (for RPE65 gene mutations).

At Preethika Eye Hospital, we emphasize a comprehensive approach, combining advanced clinical diagnostics with genetic analysis to provide the most personalized care for patients with inherited retinal diseases.