Millions of other people are also at a much higher risk of conditions including bowel disease, breast cancer and type 2 diabetes, due to their genetics, the study found.
But because they show no warning signs they are unlikely to be unaware they suffer from an increased risk.
The scientists behind the research, which was published in the journal Nature Genetics, said they hoped everyone could be given a “heart attack score” from birth that would tell their chances of suffering a heart condition on their basis of their genetics alone.
Coronary heart disease is the number one cause leading to death worldwide.
In the UK alone it is responsible for 66,000 deaths every year.
Being aware of which people are at great risk could mean doctors could take steps earlier to take counter measures, such as prescribing statins or telling patients to improve their diet and lifestyle.
Doctors currently only test people for genetic risk if their family history indicates they might have a faulty gene.
A new test, which could cost as little as £40, involves looking not at a single genetic change but at thousands, each of which can have an incremental effect on disease risk.
This was made possible by the UK Biobank, a project that was set up to follow tens of thousands of middle-aged Britons as they aged and then looked at how their health correlated to their genome.
The study of 400,000 middle-aged and elderly people revealed 0.8 percent who had the lowest genetic score for heart attack risk had coronary heart disease, compared with 11 per cent for those in the highest-scored group.
Sekar Kathiresan, from Harvard University, said the findings could significantly widen the number of people who would be warned of a genetic risk.
He said: “If you look at people who have early heart attacks before the age of 55, only 2 per cent have familial hypercholesterolemia (high cholesterol).
“This is now millions of people, most of whom are under the radar. We’ve known for ten years that half the risk of heart attack is things we know about – high cholesterol, blood pressure, obesity and smoking. This genetic score captures some of the other half.”
Dr Kathiresan said that this could be crucial information to enable people to protect themselves.
He suggested that for other diseases it may help doctors to decide who to screen in order to make an early diagnosis.
A person’s genetic risk score was worked out by looking at the millions of positions on the human genome that most often vary between people.
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