A gene has been discovered which can increase the risk of heart disease in some people by up to 40 per cent.
For these people, they can develop heart disease regardless of their cholesterol level, blood pressure and whether they have diabetes.
The research, carried out by the University of Ottawa Heart Institute (UOHI), involved a comparison of the DNA of 1,300 people with heart disease and 1.500 healthy people, observing differences in the genes.
It is hoped that the discovery will lead to a predictive gene test for heart disease.
Dr Ruth McPherson, director of the UOHI's Lipid Research Laboratory, said: "This is a common genetic variant which has a very strong effect on heart disease risk that isn't related to other factors that we already know about.
"Of the groups studied in Ottawa, about 33 per cent of people with early onset heart disease had this genetic variant versus 24 per cent of healthy elderly people."