Study demonstrates how precision medicine is advancing because of new insights from the use and interpretation of whole-genome sequencing
As part of the Genomic Medicine at Veterans Affairs Study (GenoVA), researchers from Harvard Medical School, Veterans Affairs Boston Healthcare System, and Brigham and Women’s Hospital in Massachusetts used thousands of genetic markers to develop and validate polygenic risk scores (PRS) for six common illnesses. These findings may eventually provide clinical laboratories and anatomic pathology groups with useful biomarkers and diagnostic tests.
The focus of the ongoing GenoVA study is to “determine the clinical effectiveness of polygenic risk score testing among patients at high genetic risk for at least one of six diseases measured by time-to-diagnosis of prevalent or incident disease over 24 months,” according to the National Institutes of Health.
The scientists used data obtained from 36,423 patients enrolled in the Mass General Brigham Biobank. The six diseases they researched were:
- Atrial fibrillation
- Breast cancer
- Colorectal cancer
- Coronary artery disease
- Prostate cancer
- Type 2 diabetes
The polygenic scores were then tested among 227 healthy adult patients to determine their risk for the six diseases. The researchers found that:
- 11% of the patients had a high-risk score for atrial fibrillation,
- 7% for coronary artery disease,
- 8% for diabetes, and
- 6% for colorectal cancer.
Among the subjects used for the study:
- 15% of the men in the study had a high-risk score for prostate cancer, and
- 13% of the women in the study had a high score for breast cancer.
The researchers concluded that the implementation of PRS may help improve disease prevention and management and give doctor’s a way to assess a patient’s risk for these conditions. They published their findings in the journal Nature Medicine, titled, “Development of a Clinical Polygenic Risk Score Assay and Reporting Workflow.”
“We have shown that [medical] laboratory assay development and PRS reporting to patients and physicians are feasible … As the performance of PRS continues to improve—particularly for individuals of underrepresented ancestry groups—the implementation processes we describe can serve as generalizable models for laboratories and health systems looking to realize the potential of PRS for improved patient health,” the researchers wrote.
Using PRS in Clinical Decision Support
Polygenetic risk scores examine multiple genetic markers for risk of certain diseases. A calculation based on hundreds or thousands of these genetic markers could help doctors and patients make personalized treatment decisions, a core tenet of precision medicine.
“As a primary care physician myself, I knew that busy physicians were not going to have time to take an entire course on polygenic risk scores. Instead, we wanted to design a lab report and informational resources that succinctly told the doctor and patient what they need to know to make a decision about using a polygenic risk score result in their healthcare,” epidemiologist Jason Vassy, MD, told The Harvard Gazette. Vassy is Associate Professor, Harvard Medical School at VA Boston Healthcare System and one of the authors of the research.
Increasing Diversity of Patients in Genomic Research
The team did encounter some challenges during their analysis. Because most existing genomic research was performed on persons of European descent, the risk scores are less accurate among non-European populations. The researchers for this study addressed this limitation by applying additional statistical methods to qualify accurate PRS calculations across multiple racial groups.
“Researchers must continue working to increase the diversity of patients participating in genomics research,” said Matthew Lebo, PhD, Chief Laboratory Director, Laboratory Molecular Medicine, at Mass General Brigham and one of the authors of the study. “In the meantime, we were heartened to see that we could generate and implement valid genetic scores for patients of diverse backgrounds,” he told The Harvard Gazette.
The team hopes the scores may be utilized in the future to help doctors and patients make better decisions regarding preventative care and screenings.
“It’s easy to say that everyone needs a colonoscopy at age 45,” Vassy told WebMD. “But what if you’re such a low risk that you could put it off for longer? We may get to the point where we understand risk so much that someone may not need one at all.”
Future of PRS in Clinical Decision Making
The scientists plan to enroll more than 1,000 patients in a new program and track them for two years to assess how medical professionals use PRS in clinical care. It is feasible that patients who are at high risk for certain diseases may opt for more frequent screenings or take preventative medicines to mitigate their risk.
“Getting to that point will take time,” Vassy added. “But I can see this type of information playing a role in shared decision making between doctor and patient in the near future.”
The team also established resources and educational materials to assist both doctors and patients in using the scores.
“It’s still very early days for precision prevention,” Vassy noted, “but we have shown it is feasible to overcome some of the first barriers to bringing polygenic risk scores into the clinic.”
More research and studies are needed to prove the effectiveness of using PRS tests in clinical care and determine its role in customized treatment plans based on personal genetics. Nevertheless, pathologists and medical scientists will want to follow the GenoVA study.
“It is probably most helpful to think of polygenic risk scores as a risk factor for disease, not a diagnostic test or an indication that an individual will certainly develop the disease,” Vassy said. “Most diseases have complex, multifactorial etiologies, and a high polygenic risk score is just one piece of the puzzle.”
Pathologists and clinical laboratory managers may want to stay informed as researchers in the GenoVA study tease new useful diagnostic insights from their ongoing study of the whole human genome. Meanwhile, the GenoVA team is moving forward with the 1,000-patient study with the expectation that this new knowledge may enable earlier and more accurate diagnoses of the health conditions that were the focus of the GenoVA study.