Scientists in Canada have found a piece of DNA in the human genome that increases some people’s risk of getting heart disease by up to 40 per cent, regardless of other factors such as cholesterol, high blood pressure and diabetes. They hope the discovery will lead to a predictive genetic test for heart disease.
The study, which was conducted at the University of Ottawa Heart Institute (UOHI), is published in Science, available now in the Science Express online edition.
The research was led by Dr Ruth McPherson, Director of UOHI’s Lipid Clinic and Lipid Research Laboratory in collaboration with Dr Jonathan Cohen of the University of Texas Southwestern Medical School. They hope their discovery will one day lead to a genetic test to identify people at high risk as well as help other scientists better understand the biology of heart disease.
The researchers compared the DNA of 1,300 people with heart disease to the DNA of 1,500 healthy people and looked for differences in their genes.
The participants were part of the Ottowa Heart Study, considered to be the first to scan the human genome for heart disease genes using half a million genetic markers.
The results showed that:
— A region on chromosone 9 was strongly linked to premature heart disease.
— About 25 per cent of the participants carried the variant.
— Those carrying the variant had a 30 to 40 per cent increased risk of heart disease compared to those who did not.
— This increased risk was regardless of other known risks linked to cholesterol, blood pressure, diabetes and smoking.
To confirm their findings the Canadian team collaborated with researchers working on other large scale genome-wide association (GWA) projects in the US and Denmark, bringing the overall number of participant to more than 23,000 Canadians, Americans and Danes.
The other studies had participants enrolled in the Copenhagen City Heart study, the Atherosclerosis Risk in Communities (ARIC) in the US, and the Dallas Heart Study. All three studies confirmed that this same stretch of DNA was significantly linked to coronary heart disease.
Dr McPherson said these findings were important because:
“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.”
“To put this into perspective — 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,” she added.
Dr McPherson explained that heart disease is a major cause of death in western countries where the lifetime risk of contracting the disease is one in two for men and one in three for women. She was hopeful that:
“If we can identify genetic factors which influence heart disease risk over and above known risk factors, we can do a better job of identifying those people who will benefit most from early intervention to reduce their risk.”
Speculating on their findings the researchers said the genetic variant does not seem to work through blood pressure, cholesterol and the other known risk factors so perhaps there is some new pathway. Perhaps it codes for a protein that directly promotes atherosclerosis.
“This is a stunner”, said Francis Collins, director of the National Institute of Human Genome Research in Bethesda, Maryland, one of the authors of another paper that last week pinpointed the same stretch of DNA as playing a role in diabetes.
Another study published in the same edition of Science (Anna Helgadottir et al), conducted by a team in Iceland also found a variant on chromosone 9 that pinpointed Icelanders with increased risk of heart attack.
“A Common Allele on Chromosome 9 Associated with Coronary Heart Disease.”
Ruth McPherson, Alexander Pertsemlidis, Nihan Kavaslar, Alexandre Stewart, Robert Roberts, David R. Cox, David A. Hinds, Len A. Pennacchio, Anne Tybjaerg- Hansen, Aaron R. Folsom, Eric Boerwinkle, Helen H. Hobbs, and Jonathan C. Cohen.
Published online May 3 2007; 10.1126/science.1142447 (Science Express Reports)
Written by: Catharine Paddock
Writer: Medical News Today