Medicine

How do Inherited Retinal Diseases Happen?

• June 7, 2022
• lensnframesoptical786@gmail.com

How Do Inherited Retinal Diseases Happen? The retina, a delicate layer of tissue at the back of the eye, plays a crucial role in capturing visual information and sending it to the brain. Any damage or dysfunction in the retina can lead to serious vision problems or even blindness. Among the many types of retinal disorders, inherited retinal diseases (IRDs) are particularly complex and devastating, often affecting individuals from a young age and progressing over time. But how exactly do inherited retinal diseases happen? Understanding the Retina Before diving into inherited conditions, it’s essential to understand how the retina works. The retina contains two main types of photoreceptor cells: rods and cones. Rods are responsible for vision in low light, while cones handle color and sharp central vision. These cells convert light into electrical signals, which are then transmitted to the brain through the optic nerve. In inherited retinal diseases, mutations in specific genes disrupt the normal function of these photoreceptor cells, leading to gradual cell death and vision loss. What Are Inherited Retinal Diseases? Inherited retinal diseases are a group of rare eye disorders caused by genetic mutations passed down from one or both parents. These mutations affect the proteins necessary for retinal cells to function correctly. Over 260 genes have been linked to different types of IRDs, and new ones continue to be discovered through genetic research. Some common types of IRDs include: Retinitis Pigmentosa (RP): A group of disorders that cause the breakdown of rod photoreceptors, followed by cone deterioration. Night blindness and tunnel vision are common early symptoms. Leber Congenital Amaurosis (LCA): A severe form of inherited vision loss that begins in infancy. Stargardt Disease: A type of macular degeneration that affects central vision, typically starting in childhood or adolescence. Choroideremia and X-linked Retinoschisis: X-linked diseases that mostly affect males and are passed down through the mother’s X chromosome. The Role of Genetics Genes are like instruction manuals for cells, telling them how to make the proteins that carry out vital functions. A mutation is like a typo in that manual, leading to faulty or missing proteins. In the case of IRDs, these genetic errors result in dysfunctional or dying retinal cells. Inherited retinal diseases can be passed on through different inheritance patterns: Autosomal Recessive Inheritance: Both parents carry one copy of a mutated gene but typically don’t show symptoms. A child must inherit two copies (one from each parent) to develop the disease. Example: Leber Congenital Amaurosis. Autosomal Dominant Inheritance: Only one copy of the mutated gene (from either parent) is enough to cause the disease. The affected parent has a 50% chance of passing it on. Example: Some forms of Retinitis Pigmentosa. X-Linked Inheritance: The mutated gene is on the X chromosome. Males (with only one X chromosome) are more severely affected. Females may be carriers with mild or no symptoms. Example: X-linked Retinoschisis. Mitochondrial Inheritance: Mutations in mitochondrial DNA, which are inherited only from the mother. These are less common in retinal diseases but still significant in some cases. Diagnosis and Genetic Testing Diagnosing an inherited retinal disease typically involves a detailed eye exam, imaging of the retina, visual field testing, and electroretinography (ERG) to measure the retina’s electrical activity. However, the most definitive tool is genetic testing. Genetic testing can: Identify the exact mutation causing the disease. Confirm the diagnosis. Help determine the inheritance pattern. Open the door to potential gene-specific therapies or clinical trials. Emerging Treatments Although there is currently no cure for most IRDs, exciting progress is being made in gene therapy, stem cell therapy, and retinal implants. One notable breakthrough is Luxturna, a gene therapy approved by the FDA for a specific mutation (RPE65) causing Leber Congenital Amaurosis and Retinitis Pigmentosa. It works by delivering a healthy copy of the gene directly to retinal cells, restoring some level of vision. Clinical trials for other genetic mutations are also ongoing, offering hope to many families affected by these conditions. Living with IRDs Living with an inherited retinal disease can be challenging, especially as vision declines. However, early diagnosis, low vision aids, orientation and mobility training, and supportive services can significantly improve quality of life. Genetic counseling is also essential for affected families, helping them understand inheritance patterns, risks for future children, and available support networks. Conclusion Inherited retinal diseases happen because of genetic mutations that disrupt the normal functioning of the retina’s photoreceptor cells. These mutations can be inherited in various ways, and while they often lead to progressive vision loss, advances in genetic research and therapy are offering new hope. If you or a loved one has symptoms of vision loss—especially at a young age or with a family history—it’s vital to consult an eye specialist. Early intervention, genetic testing, and staying informed about emerging treatments can make a meaningful difference. Let me know if you’d like a version tailored to a younger audience, with simpler language, or with references for medical accuracy.