Scientists have successfully developed a test for calculating a person's inherited risk for five common diseases, according to a study published Monday in Nature Genetics—and the researchers are letting individuals access the test at no cost.
In recent years, scientists have identified more than six million genetic variations in DNA that alter—sometimes by just 1%—the likelihood that an individual will get a specific disease. While the variants' small effect makes it impractical for scientists to conduct individual tests, the researchers at the Broad Institute and Harvard University sought to combine the data to determine an individual's risk score.
To do so, the researchers used genetic data to create an algorithm that calculates a person's individual risk score—called a polygenic risk score—for developing one of five diseases:
- Atrial fibrillation;
- Breast cancer;
- Chronic inflammatory bowel disease;
- Heart disease; and
- Type 2 diabetes.
The researchers tested and validated their algorithm using genetic and disease data on populations of African Americans, East Asians, Hispanics, South Asians, and White Europeans from sources such as the U.K. Biobank and 20,000 patients who had received care at the Brigham and Women's Hospital and Massachusetts General Hospital.
The researchers found the algorithm can predict a person's chances of being diagnosed with one of the five diseases at higher rates than current tests. For example, according to the Times, standard screening methods will identify two out of 100 heart attack patients who have a single genetic mutation that increases their risk. But the researchers found the new test will identify 20 such individuals.
In addition, the researchers said the test can identify people who are at the lower and higher ends of the risk range for developing the diseases.
According to the Times, the risk predictions could help patients decide what kind of care to receive. For instance, a person might use his or her risk score to help determine whether he or she should have a regular mammogram or use a statin, the Times reports.
The researchers said they are now developing a website that will allow people to upload genetic data sources, such as data they have received from Ancestry.com or 23andMe, and receive their risk scores for the five diseases. Individuals will be able to use the website and receive risk scores at no-cost.
Why providing genetic tests directly to patients is controversial
Sekar Kathiresan—one of the study's authors, director of the Cardiovascular Disease Initiative at the Broad institute, and a professor at Harvard Medical School—said some "patients are currently unaware of their risk because [they] don't have higher levels of the usual risk factors. Their cholesterol is not high. Their blood pressure is not that high. They are hidden from the current risk assessment tools."
However, Kathiresan, who also is director of the Center for Genomic Medicine at Massachusetts General Hospital, explained that the polygenic risk score is based on a much broader range of genetic mutations that can cause common diseases and, as such, can identify more patients at risk of developing the diseases than current risk assessment tools. "[I]n a few years, I think everybody will know [their polygenic risk scores], similar to the way we know our cholesterol right now," Kathiresan said.
David Maron, director of preventive cardiology at Stanford University who was not involved in the study, said the new test "carries great hope, but also comes with a lot of questions," such as "[w]ho should get tested" and "how should the results be provided?." Further, Maron said, "Physicians are not generally well trained to provide genetic test results." Maron also questioned whether the test results will lead people to care decisions that will improve their health.
Similarly, Eric Schadt—CEO of Sema4 and dean of precision medicine at the Icahn School of Medicine at Mount Sinai, who was not involved in the study—said, "Do people really understand that once you learn something you cannot unlearn it?" He added that some people might need genetic counseling before and after they receive their risk scores.
Daniel Rader, a professor of molecular medicine at the University of Pennsylvania who was not involved in the study, said physicians at the University of Pennsylvania will soon begin to incorporate polygenic risk scores into preventive care by offering offer patients their heart disease score. Rader said the university will not charge patients for their risk scores (Harper, Forbes, 8/13; Kolata, New York Times, 8/13).
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