4 Common Questions About Genetic Testing

McKenna Princing Fact Checked
A blue and green watercolor illustration of DNA.
© Liliya Rodnikova / Stocksy United

You’ve probably heard about how genetic medicine can make medical care more personalized. After all, how much more personal does it get than using data about a person’s genetic makeup to help treat medical conditions they have and prevent other conditions from occurring?

Genetic medicine is somewhat of a buzzword, though, and it can be confusing to figure out what it really means. (No, those ancestry DNA tests don’t count.) 

If you’re curious about how medical genetics can benefit your healthcare, here are answers to four common questions medical geneticists get asked. 

What conditions can genetic medicine help treat?

The most impactful way doctors can use genetic information is to prevent a patient from developing a disease, says Dr. Gail Jarvik, the head of medical genetics at the University of Washington School of Medicine who sees patients at the Genetic Medicine Clinic at UW Medical Center – Montlake. 

For example, some people get breast or ovarian cancer because of a genetic change in their BRCA1 or BRCA2 gene. 

Sometimes, people don’t get genetic tests until after they’ve developed cancer. In this case, the test results can be used to inform their treatment plan and help to prevent them from developing cancer again in the future.

If someone has a family history of breast or ovarian cancer, though, they might get a genetic test early in life. If they find out they have a genetic mutation that increases their risk for one of these cancers, they can then get regular screenings and take other steps to prevent cancer. 

In other people, a single gene mutation can actually guarantee that someone will develop a disease, not just put them at higher risk. Single-gene disorders such as Huntington’s disease and cystic fibrosis can’t necessarily be prevented, but geneticists can use a patient’s genetic information to correctly diagnose them and make sure they receive treatment that will be most helpful. 

Another way doctors can use genetic information is to help them decide which medications to give (or not give) to a patient. This is called pharmacogenetics, and while it’s still a new field of research, Jarvik says the goal is to make it more mainstream.

“It’s the idea that certain people do better or worse on certain medications, and this information would be incorporated into their electronic medical record. It should reduce a number of bad events that happen, where someone has more side effects or the drug doesn’t work for them,” she says.

Who should get a genetic test?

People who have a family history of certain diseases, such as certain forms of early onset cancer or heart disease, would often benefit from getting a genetic test, Jarvik says. 

Heart conditions like high blood pressure or certain arrythmias; cancers such as breast, ovarian and colon cancer; diabetes; and even osteoporosis can all be caused by gene mutations that are passed down in families. Any women with ovarian cancer might benefit from genetic testing.

Genetic testing can also be helpful for people who have mysterious medical symptoms but no diagnosis. Sometimes, people whose symptoms are undiagnosed have a rare genetic disorder; a test can help provide answers in the form of a correct diagnosis and guide doctors on which treatment to prescribe or ways to lessen the effects of the disease. 

Some populations have a higher risk for inheriting genetic conditions; for example, 1 in 40 Ashkenazi Jewish women will have the BRCA1 or BRCA2 gene that puts them at greater risk for breast cancer, while the CDC estimates that only 1 in 500 women in the general population has this gene (though Jarvik says this estimate is low). 

Genetic testing is also common for fetuses if the pregnant woman has risk factors, like being over age 35 or having initial prenatal tests for birth defects come back with positive results. Newer tests can assess fetal genetics by looking at the DNA circulating in the mother.

Genetic tests are relatively simple and typically require a blood or spit sample. Genetic counselors will help you understand your results and guide you on next steps. 

And no, one of those tests you get in the mail where you spit in a tube and learn about your ancestry isn’t the same as a genetic test from a doctor. (Direct to consumer medical tests can actually be more harmful than helpful.)

Does genetic medicine have racial bias?

You may have seen articles in the news about how most genetic research — the standards to which individual genetic tests are compared — has focused on people of European ancestry. This is unfortunately true, although the situation is improving.

“There are many rare variants in genetics and understanding whether those do or do not cause disease is very important. Variants are different in different ancestry groups, so if you haven’t looked a lot in a certain group you may see a variant you think is concerning, but if you had enough data on enough people you’d find out it was more common in some groups,” Jarvik explains.

Despite small genetic variations that can have a big impact and differences among people of different ethnicities, it’s important to note two things. One is that all humans, regardless of race or ethnicity, share about 99.9% of our DNA. (Plus, race is a social construct, not a biological one.) Two is that, when it comes to someone’s health, that 0.1% can make a big difference.

Learning about genetic variation for people of all races and ethnicities, not just white people, is something researchers are actively working on. This is important not just for healthcare equity, but for our understanding of genetic diseases.

How easy is it to access genetic medicine services?

Removing barriers that keep people from getting genetic tests and accessing other services is another must-have in order to make genetic medicine more equitable, Jarvik says.

“The cost of genetic testing has dramatically come down in the last four or five years, but we still have a problem with insurance companies not paying for tests; we have more patients now who self-pay,” she says.

Of course, not everyone can afford to do that. Whether or not insurance covers genetic testing and other services largely depends on the insurance plan someone has and, as with most medical coverage, some plans are better than others. 

Another issue is physical access. At the clinic where Jarvik works, some patients traveled hours from faraway areas in Washington state to get care — pre-coronavirus, that is. Now that more patients are utilizing telehealth services for genetic consultations, Jarvik is hopeful this will be a long-term solution for patients who don’t live in or near Seattle.

“Adult genetics is a good specialty for telehealth because often we don’t need to give the patient a physical examination,” she explains.

The future of genetic medicine

Along with diversity in genetic research and improving access to care, Jarvik is hopeful that the near future will show decreased costs for some of the newer testing techniques, such as pharmacogenetics. Currently, this testing is expensive, she says.

Another thing she’s interested in is polygenic risk score research, which analyzes an individual’s risk for common conditions that are important causes of illness in the U.S., based on their genetic data — and more of their genetic data, not just a small part of it. 

“Instead of looking at one single gene change, it’s like evaluating the whole set of cards they were dealt,” Jarvik says.