New research shows that scanning people’s DNA profiles to compile a genetic risk score can improve the prediction of heart disease compared with traditional clinical risk scoring. The researchers say this should increase the opportunity to intervene early and help affected people reduce their risk – for instance through lifestyle changes.
The study, published in the European Heart Journal, is the work of an international team, including members from the University of Melbourne in Australia.
The authors explain that at present, doctors calculate people’s risk of developing heart disease by assessing a range of clinical and lifestyle factors, such as blood pressure, smoking, and alcohol consumption.
Family history is also included in the assessment. However, despite advances in genomic technologies, genetic information based on an individual’s DNA profile is currently not used to assess risk for heart disease.
Heart disease is an umbrella term for a range of disorders that affect the heart, of which coronary artery disease is the most common.
Every year, about 610,000 Americans die of heart disease, the majority from coronary artery disease, where plaque builds up in the walls of the arteries that supply blood to the heart.
As the plaque – made up of deposits of cholesterol and other substances – builds up in the arteries, they gradually get narrower and narrower. Eventually, the process, called atherosclerosis, can totally or partially block the flow of blood.
When the heart muscle does not get enough blood, it can lead to angina, causing chest pain and discomfort. Angina is the most common symptom of coronary artery disease. Other disorders can also develop, such as heart failure or irregular heartbeat.
Mike Inouye, associate professor in Melbourne’s School of BioSciences and senior author of the new study, explains the significance of their work:
- Every year about 735,000 Americans have a heart attack
- Heart disease is the leading cause of death for both men and women in the United States
- Each year, heart disease costs the U.S. about $207 billion in healthcare services, medications, and lost productivity.
“About half of heart disease risk is inherited, yet current approaches don’t use genetics. Our study shows that we can potentially distinguish much earlier in life who is at high risk of heart disease, including heart attack.”
First, from an analysis of large genetic studies of heart disease by the CARDIoGRAMplusC4D Consortium, he and his colleagues developed a genetic risk score based on over 49,000 Single Nucleotide Polymorphisms (SNPs) – small sections of DNA that vary from person to person, rather like different spellings of the same word.
They then independently tested the genetic risk score using five prospective population cohorts from different large-scale studies of heart disease totalling over 16,000 participants.
They found not only that the genetic risk score was able to predict heart disease earlier on its own, but also integrating it into current clinical risk scoring methods improved the 10-year risk prediction, particularly for individuals aged 60 and over.
Lead author Dr. Gad Abraham, a computational biologist in Prof. Inouye’s systems genomics lab, says:
“Traditional scores can identify people at very high risk, but without an understanding of the genetics, we still fail to identify a large proportion of people who are going to develop heart disease over the next 10 years.”
The authors note that an important feature of the genetic risk score is that it captures “substantially different trajectories of absolute risk.”
They found it picked out men in the top 20 percent of attaining high cumulative lifetime risk some 12-18 years earlier than those in the bottom 20 percent.
The team concludes that a genetic risk score based on a large number of SNPs improves heart disease “risk prediction and encodes different trajectories of lifetime risk not captured by traditional clinical risk scores.”
“So far, we’ve been missing half the picture, but given the great strides being made by genomics in understanding human disease, we expect this approach to one day be part of routine clinical practice.”
Dr. Gad Abraham