The current way doctors evaluate a patient's risk for coronary heart disease involves monitoring one's blood pressure and cholesterol while also identifying other factors such as smoking, family history or diabetes. The problem with this strategy is that it is age-dependent, with monitoring only beginning when a person reaches the age of 40 or 50, and it misses a large volume of people who are seemingly otherwise healthy yet get struck down by sudden heart attacks.
Impressive work from an international team of researchers has now resulted in what they are calling a Genomic Risk Score (GRS), which can assess a person's genetic risk factor for developing coronary heart disease. Using genomic data from nearly half a million people, and analyzing nearly two million different individual genetic variants, the test could be a missing link in diagnostic tools, allowing doctors to combine a GRS with other risk factors so as to better target at risk individuals.
In evaluating the efficacy of the new genetic test against six conventional risk factors (smoking, blood pressure, body mass index, diabetes, family history, and high cholesterol) the research found the GRS was better at predicting whether a person would develop heart disease than any other single risk factor. Overall, those with a GRS in the top 20 percent were four times more likely to develop heart disease compared to those with a GRS in the bottom 20 percent.
Perhaps the most significant metric raised in the study was the finding that males with a high GRS score that were otherwise healthy were as likely to develop coronary heart disease as males with at least two conventional risk factors (i.e. high cholesterol and blood pressure) but a low GRS score. This suggests that the GRS could be an incredibly useful addition to the other diagnostic risk factors already utilized by clinicians, allowing better preventative targeting of those who may otherwise seem healthy.
The other big benefit in incorporating this kind of genomic testing into common practice is that it can be measured at young ages, before other symptoms or risk factors take hold. The GRS is suggested to cost no more than US$50 per test, allowing for a cheap, one-off insight into persons at high risk and hopefully allowing for early preventive strategies to be offered.
"At the moment we assess people for their risk of coronary heart disease in their 40's through NHS health checks," explains Nilesh Samani, senior author on the paper. "But we know this is imprecise and also that coronary heart disease starts much earlier, several decades before symptoms develop. Therefore if we are going to do true prevention, we need to identify those at increased risk much earlier."
Michael Inouye, lead author on the new study, suggests the exciting new combination of big data science and extraordinarily large genomic cohorts has allowed scientists to develop these novel genetic tests. Inouye admits genes are only one part of the story in whether a person will ultimately develop coronary heart disease, but the data is now accurate enough for these tests to become a valid additional tool in a doctor's arsenal.
"While genetics is not destiny for coronary heart disease, advances in genomic prediction have brought the long history of heart disease risk screening to a critical juncture, where we may now be able to predict, plan for, and possibly avoid a disease with substantial morbidity and mortality," says Inouye.
The new study was published in the Journal of the American College of Cardiology.
Source: British Heart Foundation
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