By Alexandra Rachitskaya, MD, as told to Hailey Levin
Being diagnosed with hereditary retinal dystrophy (IRD) can be devastating. These rare, hereditary eye diseases cause progressive vision loss, and sometimes blindness. Here at the Cleveland Clinic, we see more patients with IRD than ever before. Our strength has grown from 327 patients in 2015 to nearly 800 in 2019. Cause? We’ve gotten a lot better at both diagnosis and treatment.
Over the past 2 decades, we have learned that there are approximately 300 genes associated with IRD. Thanks to advances in genetic testing technology, we are able to diagnose gene mutations in over 70% of all cases.
This is good news, because once we know which genetic mutation is driving your disease, we can often refer you for an appropriate clinical trial that will help improve or maintain your vision. Can do. Even if we can’t now, thanks to gene therapy, there’s a very real chance that in the next decade or two, there could be a revolutionary new treatment to save your sight.
Here’s why we’re so excited about gene therapy, what’s available now, and how to go about finding a clinical trial near you.
Why gene therapy is so promising for IRD
In gene therapy, an abnormal gene is replaced with a normal gene. While there are many ways to do this, the most common method is to use a vector – a virus without the disease-causing parts – to deliver a healthy gene into cells. This is done through eye surgery by a doctor. The hope is that the cells with the new, functional copy of the gene will now work properly.
As it turns out, the eye itself is actually an ideal candidate for gene therapy. There are a couple of reasons for this. One is that it is relatively easy to reach the retina compared to other parts of your body, such as your heart or lungs. The second is that the eye is “immune privileged”. This means that its immune response is not as active as in other parts of the body. This is important, because when a virus vector containing a normal gene is injected into the eye, you don’t want the eye’s immune response to be triggered.
What treatments are currently available for IRD?
There is only one FDA-approved gene therapy for inherited retinal disorders: Luxturna, which was approved in 2017. This is especially true for people with IRD who have the mutation. RPE 65 Jean. This can be seen in two diseases: retinitis pigmentosa and Leber congenital amaurosis (LCA). Provides a functional copy of the treatment RPE 65 Genes in retinal cells of the eye. These cells then produce the normal protein that converts light into an electrical signal to the retina. This helps slow the progression of the patient’s disease and vision loss.
The first thing patients with these forms of IRD notice is that they have trouble seeing at night. They then begin to lose their peripheral, or side vision, then finally, their central vision. During clinical trials of Luxturna, researchers had patients go through a mobility maze before and after treatment. Almost all of them also saw a significant improvement in their ability to navigate the maze in dark environments, which are usually more difficult. There are some wonderful stories of children who have had their sight returned by this procedure.
Several other clinical trials are underway at medical centers across the country. Here at the Cleveland Clinic, we’re enrolling patients with a type of retinitis pigmentosa called X-linked retinitis pigmentosa. Since it is an X-linked disorder, it mainly affects males, as they have one copy of the X chromosome that carries the mutation. (In females, the effect of the mutation is masked by a second healthy copy of the X chromosome. But they can still be carriers of the disease and sometimes have visual changes.) We try to target one eye of eligible patients. use gene therapy. To try to prevent the disease from progressing to more severe stages.
Other gene therapy clinical trials are also underway for other IRDs, such as choroideremia and achromatopsia. It shows promise in halting the progression of vision loss, and sometimes even improving vision.
Why gene therapy offers hope to people with IRDs
Gene therapy has the potential to revolutionize the treatment of hereditary retinal disorders. Just a decade ago, patients would see eye doctors and be offered nothing more than low vision therapy. Now, we can test them for the specific genetic mutations that cause disease, and ideally pair them with a gene therapy test to replace that bad gene.
It’s important to understand that if you have IRD and it’s already very advanced, introducing a healthy normal gene won’t do much. You want to catch and treat the disease before it progresses too far. That’s why genetic testing is so important. Once that is done, we can search nationwide to see if there are any clinical trials available. You can keep yourself updated about active and recruiting clinical trials in the United States or even globally through https://clinicaltrials.gov.
I think it’s important to stay on top of your eye health, even if you don’t have a diagnosed IRD, but a family history of one. If recommended by your doctor or genetic counselor, it is important to get genetic testing to make sure you are not a carrier, and to encourage other family members to get tested as well. This way, an IRD can be raised sooner.
Looking even further down the pipeline, there’s a lot of excitement around cell therapy. This is where diseased retinal cells are replaced with stem cells that can develop into healthy ones. Studies on this are still in very early stages, and the science is not as strong as for gene therapy. But this type of treatment may hold promise, not only for people with IRD, but also for people with other more common diseases of the retina, such as age-related macular degeneration.
Overall, the future has never been brighter for people with IRDs. We can’t promise them 20/20 vision, but hopefully we can introduce them to a clinical trial that may improve their vision.
