Hundreds of genes play a role in inherited retinal dystrophy (IRD). That includes a set of rare eye disorders passed down through the DNA of families. Genetic testing for IRD may help your eye doctor find gene changes or mutations behind your retinal disease.
IRDs lead to vision loss that worsens over time, sometimes causing blindness. The right diagnosis early on may boost your long-term eye health and help you plan for the future. The genetic cause of your IRD may also impact your access to current clinical trials and new and future gene therapies.
Here’s some information about genetic testing for IRD, but work with your doctor to decide if it’s right for you.
Who Should Get Genetic Testing?
You’re a good candidate if you or your child already have an IRD diagnosis associated with a known gene change. A diagnosis is a big help because many genes are associated with retinal disorders. And the person reading your genetic test needs to know what mutation or mutations to look for.
In other words, your doctor may use “diagnostic” genetic testing when they already have a good guess about what type of IRD you have. Retinal diseases can be hard to identify just by looking at your eye. But your doctor can use genetic tests to confirm they’re on the right track.
They may also suggest genetic testing for your close relatives (parents, siblings, kids) if you test positive for a gene associated with IRD. That means your family history may qualify you for “predictive” genetic testing, even before you have telltale signs of retinal disease.
Genetic testing for IRD isn’t recommended for those without a diagnosis of IRD or those without a family history of retinal diseases.
What Are the Pros and Cons of Genetic Testing?
There are many ways genetic testing might be useful if you have a suspected IRD. For starters, a test that pinpoints your gene mutation can confirm your doctor’s diagnosis and treatment plan.
A positive genetic test for IRD can also:
- Tell you more about how your vision loss may progress
- Impact your current or future treatment options
- Get you in the right clinical trial
- Tell you which family members need testing
Some gene changes are passed down through many generations, while others may only affect one. But you may not know this inheritance pattern, or the chances you’ll pass on the gene to your kids, without testing for a specific mutation.
Genetic testing may also shed light on the cause of other health conditions.
For example, some IRD genes may lead to hearing loss or kidney damage. If you don’t have these health problems yet, genetic testing could tell you what signs to watch for or how to prepare for the future.
Keep in mind there are hundreds of genes known to cause IRDs, but some are unknown. And a genetic test may not always find the one you have. Around 30% of those tested for an IRD gene change may get a negative result.
These tests may not be the right choice for everyone.
You may decide not to go ahead with genetic testing if you’re symptom-free and there’s no treatment for the kind of IRD you might get later on. A genetic counselor can help you weigh the pros and cons of making these decisions for yourself or your child.
Does Genetic Testing Affect Treatment?
Right now, there’s only one gene therapy approved to treat IRD. It’s used to stop disease progression in kids and adults who have a mutation in both copies of the RPE65 gene, which includes people with Leber congenital amaurosis.
But even if a gene therapy doesn’t exist for your type of IRD, genetic testing may change your treatment in other ways. That may include:
Access to clinical trials. Scientists continue to study new gene therapies for IRD. You may be able to try one of these new drugs before they’re approved for the general public.
But your doctor needs to know which gene mutation you have in order to match you with the right clinical trial.
Which medication you can take. You shouldn’t take a vitamin A supplement if you have Stargardt disease, Best disease, cone-rod dystrophy, or other forms of inherited macular degeneration. These conditions are caused by a buildup of toxic breakdown products of vitamin A. Genetic testing can tell your doctor if you test positive for gene changes associated with those conditions.
How Can You Prepare for Genetic Testing?
There are several steps in the genetic testing process. You may need to:
Get detailed retina tests. It’s helpful to find what genetic mutation you might have. The best person to do that is a retinal specialist who knows a lot about IRDs. They’ll use specialized tests to look at the cells, blood vessels, and structure of your retina.
To help guide your genetic testing, you may first need one or more of the following:
- Optical coherence tomography
- Other retinal imaging
- Visual field testing
- Electroretinography
Talk to a genetic counselor. These are health professionals who know the ins and outs of genetic testing. They’ll help you decide if these tests are right for you or your child.
To make the most of your appointment, you can:
- Write down any questions ahead of time.
- Make a list of any other medical conditions.
- Find out the diagnosis of anyone in your family with vision problems.
- Learn about any other health problems that run in your family.
- Find out if any of your family members have died early from cancer or other illnesses.
Try to get as many details as possible when it comes to family members affected by retinal diseases. And if any of them has had genetic testing, try to get copies of their report. That can speed up the process for you and your medical team.
Give a DNA sample. Genetic testing typically uses only a little of your blood or saliva. This process is similar to other common lab tests, but your doctor should let you know what to expect.
Wait for the results. You may not hear back about your tests for 2 to 3 months. But your genetic counselor will help you understand the results.
They’ll work with your doctor to help you figure out next steps or if you need genetic testing in the future.
How Much Does Genetic Testing Cost?
In general, genetic testing is less expensive today than it was in the past.
How much you’ll pay depends on where you get your test and the kind of medical coverage you have.
The good news is there’s a lot of research interest in this area. And people with IRDs can usually get genetic testing done for free without ever needing to bill medical insurance.
Ask your doctor or genetic counselor about sponsored programs that may cover your costs. These include nonprofit or commercial groups who use your information to learn more about IRD and its treatment.
Find more information about free genetic testing through the My Retina Tracker Genetic Testing Program. A nonprofit group called the Foundation Fighting Blindness sponsors this program, which may be able to match you with a clinical trial or gene therapy.
