Genetic Testing Companies Are Facing a Racial Bias Problem in Disease Risk Tests

Genetic Testing Companies Are Facing a Racial Bias Problem in Disease Risk Tests

The large genetic studies underlying certain disease risk tests have primarily been done in populations of European ancestry, limiting their accuracy.

Earlier this year, California-based Ambry Genetics announced that it was discontinuing a test meant to estimate a person's risk of developing prostate or breast cancer. The test looks for variations in a person's DNA that are known to be associated with these cancers.

Known as a polygenic risk score, this type of test adds up the effects of variants in many genes — often in the dozens or hundreds — and calculates a person's risk of developing a particular health condition compared to other people. In this way, polygenic risk scores are different from traditional genetic tests that look for mutations in single genes, such as BRCA1 and BRCA2, which raise the risk of breast cancer.

Traditional genetic tests look for mutations that are relatively rare in the general population but have a large impact on a person's disease risk, like BRCA1 and BRCA2. By contrast, polygenic risk scores scan for more common genetic variants that, on their own, have a small effect on risk. Added together, however, they can raise a person's risk for developing disease.

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Emily Mullin
Emily Mullin is a science and biotech journalist whose work has appeared in The Washington Post, New York Times, Wall Street Journal, Scientific American, National Geographic and Smithsonian Magazine.
This man spent over 70 years in an iron lung. What he was able to accomplish is amazing.

Paul Alexander spent more than 70 years confined to an iron lung after a polio infection left him paralyzed at age 6. Here, Alexander uses a mirror attached to the top of his iron lung to view his surroundings.

Allison Smith / The Guardian

It’s a sight we don’t normally see these days: A man lying prone in a big, metal tube with his head sticking out of one end. But it wasn’t so long ago that this sight was unfortunately much more common.

In the first half of the 20th century, tens of thousands of people each year were infected by polio—a highly contagious virus that attacks nerves in the spinal cord and brainstem. Many people survived polio, but a small percentage of people who did were left permanently paralyzed from the virus, requiring support to help them breathe. This support, known as an “iron lung,” manually pulled oxygen in and out of a person’s lungs by changing the pressure inside the machine.

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Sarah Watts

Sarah Watts is a health and science writer based in Chicago.

When doctors couldn’t stop her daughter’s seizures, this mom earned a PhD and found a treatment herself.

Savannah Salazar (left) and her mother, Tracy Dixon-Salazaar, who earned a PhD in neurobiology in the quest for a treatment of her daughter's seizure disorder.

LGS Foundation

Twenty-eight years ago, Tracy Dixon-Salazaar woke to the sound of her daughter, two-year-old Savannah, in the midst of a medical emergency.

“I entered [Savannah’s room] to see her tiny little body jerking about violently in her bed,” Tracy said in an interview. “I thought she was choking.” When she and her husband frantically called 911, the paramedic told them it was likely that Savannah had had a seizure—a term neither Tracy nor her husband had ever heard before.

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Sarah Watts

Sarah Watts is a health and science writer based in Chicago.