Simple blood test may predict risk of heart attack

By Suzanne Morrison, February 11, 2009

    Dr. Sonia Anand, a professor in the Michael G. DeGroote School of Medicine at McMaster University and researcher within the Population Health Research Institute. Photo courtesy of FHS.
In the not-too-distant future, a simple blood test may predict the genetic risk of suffering a heart attack - no matter what your ethnic background.

Dr. Sonia Anand, a professor in the Michael G. DeGroote School of Medicine at McMaster University and researcher within the Population Health Research Institute, led a group of Canadian and British researchers who pinpointed specific genes and their association with an increased risk of heart attack.

Their research - Genetic Variants Associated with Myocardial Infarction risk Factors in over 8,000 Individuals from Five Ethnic Groups: The INTERHEART Genetics Study - appears in a recent online edition of Circulation Cardiovascular Genetics.

Dr. Anand and her team extracted DNA from the INTERHEART case-control study of 8,795 individuals of European, south Asian, Arab, Iranian and Nepalese origin and genotyped 1,536 single nucleotide polymorphisms (SNPs) from 103 genes.

SNPs are single base pair variations in DNA which occur within genes and, in some cases, change the production of proteins or alter the expression of other genes. (Scientists believe common SNPs may be associated with the development of some common chronic diseases such as cancer, diabetes, vascular disease and some forms of mental illness).

Their results show a "significant" association between four genes, and high cholesterol levels, particularly ApoB/A1 levels - ApolipoproteinB which is the primary protein involved in "bad cholesterol" and responsible for carrying cholesterol to tissues. In the current study, the researchers concluded 13 common SNPs were associated with heart disease risk factors and 1 variant was independently associated with the risk of a heart attack.

The earlier INTERHEART study led by Dr. Salim Yusuf, director of the Population Health Research Institute and professor at McMaster University, showed nine risk factors accounted for more than 90 per cent of the risk for heart attacks globally. Those nine risk factors are dyslipidemia/high cholesterol, diabetes, hypertension, abdominal obesity, tobacco, physical inactivity, psychosocial stressors, low fruit and vegetable intake and no alcohol consumption. Together the genetic variants(SNPs)increased the prediction of risk of MI by 1.6 per cent.

"Most genetic studies have focused on studying white Caucasians," said Dr. Anand. "The unique contribution of our study is that we demonstrate that common genetic variants are indeed common across 5 ethnic groups. Furthermore, we are able to put the contribution of these factors on the risk of heart attack into perspective, demonstrating that the nine risk factors account for the vast majority of heart attacks and the genetic variants while important only add a small independent contribution to the risk of heart attack."

In addition to researchers from McMaster University, the research team included investigators from McGill University and the Genome Quebec Innovation Centre; the Institute of Human Genetics, Newcastle upon Tyne, United Kingdom and the Ontario Institute for Cancer Research.

Dr. Anand is also a member of the Myocardial Infarction Genetics Consortium. In a separate paper published also this week in Nature Genetics Online, the consortium compared the genomes of about 3,000 people who had suffered heart attacks relatively early in life - under 50 in men, under 60 in women - with those of 3,000 people who hadnt had a heart attack.

This genome-wide study identified nine spots associated with an increased risk of heart attack. The 20 per cent of people who had the most unfavourable genetic profile had a 2.25-fold greater risk of having a heart attack, compared to the 20 per cent with the best genetic profile.

Dr. Anand is the director of the Population Genomics Program in Hamilton and holds the Michael G. DeGroote and Heart and Stroke Foundation of Ontario Chair in Population Health and the May Cohen Eli Lilly Endowed Chair in Women's Health Research, McMaster University.