The Importance of Genetic Testing
By MDA Staff | Thursday, January 16, 2020
Kelly Berger, 31, of Cincinnati, spent most of her life chasing a diagnosis. When she was 3, her parents noticed that, although she reached physical milestones for her age, she did them in unusual ways. For example, to step up, she pushed off her thighs with her hands, and she preferred crawling on stairs to walking them. Her parents took her to a neurologist and, after bloodwork, an electromyography (EMG), and a muscle biopsy, she received a diagnosis of spinal muscular atrophy (SMA) type 3. That was in the early 1990s, when fewer types of neuromuscular disease were understood.
“Fast-forward to my mid-teens,” Kelly recounts. “After more bloodwork, another neurologist concluded that my tests showed I didn’t have the SMA gene mutation. They settled on congenital muscular dystrophy [CMD], type undefined. I was my own category. Kind of cool when you think about it.”
But Kelly and her neurologist weren’t ready to give up on getting an accurate diagnosis. Finally, in 2017, genetic tests run on blood samples and a skin biopsy showed she has collagen VI A1 intron 11, a rare type of CMD.
Searching for answers
Struggling to get an accurate diagnosis is a common experience among people living with neuromuscular diseases. In a survey of more than 3,000 individuals living with a neuromuscular disease or a family member who has one, MDA found 25% have not had their diagnosis confirmed through genetic testing.
Having a genetically confirmed diagnosis is important because it can lead to better treatment and open doors to participating in clinical trials and other research aimed at treatments and cures.
Genetic testing not only is used to confirm a diagnosis but also can help predict how a disease will progress and give physicians vital information for targeting therapies to an individual’s disease.
“Recently, we had a case of an individual who had been visiting his neurologist for many years without a clear diagnosis,” says molecular geneticist Madhuri Hegde, PhD, FACMG, a professor at Emory University School of Medicine and vice president and chief scientific officer of PerkinElmer Genomics. “When the sample was sent to us for genetic testing, the neurologist was planning a muscle biopsy, which can be painful. We were able to find a disease-causing change in the GAA gene, which can cause adult-onset Pompe disease, and thereby did not need the invasive procedure.” That genetic diagnosis also allowed the individual to start enzyme-replacement therapy, currently the most effective treatment for Pompe disease.
Advances in genetic testing
Genetic testing becomes more accessible and accurate every year. This has as much to do with scientific discoveries in the neuromuscular disease field as it does with advances in testing technology.
Genetic tests look for specific gene mutations that are known to be associated with particular diseases. Genetic mutations have been identified for a fraction of the many neuromuscular diseases we know. But scientists are continuing to search for and identify more disease-causing gene mutations. With each discovery, the possibilities for genetic testing expand.
At the same time, testing technology is improving. “Years ago, we could only test for one gene at a time,” says Kristin Engelstad, MS, CGC, a genetic counselor at Columbia University. “As the technology changed, we had tests that could cover more. Now, if I have a patient with muscle weakness, I can check 70-100 genes for sequencing.”
In addition to finding gene mutations, some test panels can evaluate how a patient will respond to a particular treatment.
Where to start
If you’re considering genetic testing, begin by talking with your doctor and a genetic counselor. They will consider your symptoms and family history to determine the appropriate tests to order.
Most genetic tests involve taking a blood sample or cheek swab, which is sent to a lab for testing. When the results are in, the physician and genetic counselor will share the results and advise you on appropriate treatments or clinical trials.
Some people are hesitant to undergo genetic tests when there is no cure for their disease. But at a time when science is advancing quickly in the field of gene-targeted therapies, it makes sense to have a genetically confirmed diagnosis in order to be prepared as new therapies emerge.
Having an accurate diagnosis can have positive impacts on other areas of your life. For example, you and your family may be able to plan for the future knowing the possible progression of your disease. You may also find social networks of people who share the same diagnosis.
Since receiving her genetically confirmed diagnosis, Kelly has joined a clinical trial. She hopes she can help advance research and discover treatments for her condition.
She’s found another benefit that is less tangible but no less important. “I finally have the answer to that question that’s been lingering my whole life,” Kelly says. “Yes, it’s just a name and some numbers; it ultimately doesn’t define me. But it feels like I have a bit of closure after not knowing for so long.”
Donna Albrecht is a health writer based in San Francisco.
The First Step to Testing
If you’re interested in genetic testing, talk with the care team at your MDA Care Center.
What’s a Genetic Counselor?
Genetic counselors are medical professionals who have advanced training in medical genetics and counseling. Their role is to guide and support patients and families who are seeking information about genetic conditions.
At MDA Care Centers, genetic counselors are often part of multidisciplinary care teams. Your doctor may refer you to a genetic counselor before or after genetic testing.
Jennifer Roggenbuck, MS, CGC, a genetic counselor and associate professor at the Ohio State University Wexner Medical Center, explains that when she meets with a patient, she begins by asking about their family and medical history. With this history, she can address concerns about diseases that might run in the family, and she can recommend specific genetic tests.
“It’s important that patients and clinicians understand the possible outcomes before embarking on the testing journey,” Jennifer says.
After genetic testing, she can help patients and their families understand test results and provide them with emotional support as they continue on that journey.
My doctor gave me a diagnosis. Why should I get a genetic test?
Genetic testing can improve the accuracy of a clinical diagnosis by pinpointing an individual’s disease-causing mutation. This can lead to eligibility for certain therapies or medications and clinical trials, as well as a better understanding of how the disease will progress.
Can’t I order a genetic testing kit on the internet?
There are many DNA testing kits on the market that claim to reveal your ancestry or provide health insights. But over-the-counter genetic testing kits can’t match the specificity of the tests ordered in a clinical setting and don’t offer the clinical help and counseling your care team delivers with test results.
I already had a genetic test. Do I need another?
Genetic testing is advancing quickly. If your previous genetic test was negative or inconclusive, keep asking about new testing. Anyone considering a gene-targeted therapy also should ask if their testing needs to be repeated.
Is genetic testing expensive?
Genetic testing is becoming more affordable. MDA’s Resource Center may be able to help you find resources for genetic testing. Call us at 833-ASK-MDA1.
If I have a diagnosis, should my family be tested?
Talk with your genetic counselor about who in your family should be tested based on the type of disease and who else is showing symptoms. Relatives may be interested in genetic testing to find out if they are carriers. Carriers have a chance of having children with the same genetic disease.
Disclaimer: No content on this site should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.