By Gina DeMillo Wagner

Rare disease is a way of life for an estimated 30 million people in the U.S. and 400 million people worldwide. Experts believe that about 80 percent of rare diseases have a genetic origin. As a result, most rare disease patients will consider genetic testing at one point or another.

That’s where geneticists come in. If patients are lucky, they will meet with a doctor like Joshua Owens, MD, a genetics resident at Cincinnati Children’s Hospital. Through his work, Dr. Owens encounters families seeking answers to the range of mysterious symptoms and diseases that have genetic origins. Dr. Owens has made it his personal mission to help demystify genetics so that his patients feel safe and empowered. He uses visual aids like LEGO models, which his young patients readily understand. And, from the get-go, he views parents and caregivers as knowledgeable partners in the patient’s care. 

On average, Dr. Owens says, families might spend years navigating traditional healthcare systems before they receive a diagnosis. The variability in an individual’s genetics and symptoms makes the process more complicated. The journey from symptoms to diagnosis can put a lot of strain on not only families, but also the clinicians who want to help. 

Having precise, affordable, accessible genetic testing options reduces the time to diagnosis and saves patients and families a lot of stress.

Having precise, affordable, accessible genetic testing options reduces the time to diagnosis and saves patients and families a lot of stress. “We’ve come a long way since the human genome project in the 1990s,” Dr. Owens notes. “Back then, the first genome cost about 3 billion dollars and 13 years to get results. Now, we can sequence a genome in a matter of weeks for several thousand dollars.” More basic genetic tests are even more affordable. They use blood or a spit sample, and results are typically ready in a few weeks. 

But what exactly does “genetic testing” mean? What kinds of tests are out there? And what information do they provide?

Dr. Owens sat down with us and explained the options available for genetic testing. He also answered some common questions he hears from the families he treats:

1. What types of genetic testing are available? 

Genetic tests are not one-size-fits-all, Dr. Owens says. Testing should be individualized based on your unique symptoms, medical history, and family history. Some tests look exclusively at whether a patient has extra or missing copies of certain genes. Meanwhile, others look for “spelling errors,” he says, which means the gene is there, but it isn’t made properly. “There might be too much protein added to the gene or a piece of the gene is missing,” he explains. “As a result, the gene may interact with the body differently.”

Single-gene testing finds changes or abnormalities that affect only one gene. Your doctor may recommend this if you or your child shows symptoms of a specific condition, such as sickle cell disease. Single-gene testing can also help in families where there is a known mutation that doctors are looking for. Panel testing is broader and looks for changes in several genes in one test. This may be prescribed when a patient has symptoms that fit a variety of genetic disorders, or when a disease is linked to several genes. Exome sequencing looks for changes in all known genes that play a role in human health. Finally, genome sequencing is the largest genetic test and looks at all of a person’s DNA, not just the genes. 

2. What can genetic testing results tell you and your doctors?

Genetic testing results generally fall into one of three categories, Dr. Owens notes: 

• A positive or pathogenic result means the test found a genetic change that is known to cause disease. 

• A negative or benign result means the test did not find a genetic change for the genes that were tested. 

• Finally, a “maybe” or “variant of unknown significance” result means the test found a genetic variation, but it’s unclear whether that variation has any significance for the patient. In other words, the variation may or may not affect your health.  

Going over test results with your doctor is the best way to understand what they mean for you, he says. As testing becomes more widely available, patients are uncovering genetic differences that might have gone unnoticed before. You may worry about certain outcomes, but geneticists know that not every positive result is severe. “There’s a huge range of presentations for any given genetic change, and two patients with the same genetic change can have different symptoms,” Dr. Owens explains.  

3. What are the benefits and risks of testing?

For families with a history of rare disease or known genetic variants, early genetic testing can provide peace of mind and/or a head start on life-saving treatments. Testing can also assist family planning decisions and connect patients with the right experts, treatments, clinical trials, and support networks. Some doctors are using genetic testing in precision medicine, so that they can carefully match drugs and other treatments to the patient’s unique genetic makeup. The investment up front in testing can save patients thousands of dollars, if not more, in medical costs down the road. More importantly, early genetic testing may result in better health outcomes.

That said, there’s a risk in relying too heavily on genetic testing, Dr. Owens warns. A genetic test doesn’t account for a person’s lifestyle, environment, stress, and socioeconomic factors—all of which affect health. Plus, testing too widely without reason can cause undue anxiety. You might uncover a genetic anomaly that will never cause problems for you. “There’s a lot of focus on single-gene disorders, but in reality, we know there are hundreds of other genes interacting with that one defective gene,” Dr. Owens says. A test alone won’t tell you what the future looks like for a given patient. 

4. How can I find out more about testing?

Ask your doctor or care team about genetic testing options available to you. There’s also a directory of medical geneticists available through the American College of Medical Genetics and Genomics. 

Remember, if you’re unsure about whether to undergo genetic testing, you can attend genetic counseling first. A genetic counselor can work with you before and after genetic testing to make sure testing is appropriate for you, to help you know what to expect during testing, and to help you understand the results. You can find a genetic counselor in your area through the National Society of Genetic Counselors. 

To connect with experts and clinical trials for your rare disease, click here.