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Twin studies find Genetic link to Heart disease

Two separate studies have discovered a common genetic variation that dramatically raises the risk of coronary heart disease (CHD) and doubles the chances of younger people suffering a heart attack in early age.

A team of US and Canadian scientists using powerful state-of-the-art genetics research methods has for the first time identified a strand of DNA which they claim increases the risk of heart disease and heart attacks by around 40%. Another study in Iceland found that the same genetic variant was linked to a fifth of heart attacks.

Researchers said the high-risk stretch of genes is common among Caucasian populations, with up to 50 percent carrying one copy of it, and about 20 percent of people inheriting two copies, one from each parent. It is much less prevalent in people of African descent, the researchers said.

To reach their conclusion, both teams of researchers scanned the genomes of more than 40,000 patients who had coronary heart disease or who had suffered a heart attack in order to see if there were any differences between them and healthy people.

The two separate reports, which are published in the journal Science, alighted on a single nucleotide polymorphism (SNP) that lies close to two genes called CDKN2A and CDKN2B. Both groups spotted snips in a small region of Chromosome 9 (the human genome is packaged into 23 pairs) as being associated with higher risk of heart disease.

The study by US/Canadian researchers, led by Ruth McPherson at the University of Ottawa Heart Institute in Canada, showed that those who carried one copy of this section of DNA, called an allele, have a moderately increased risk of heart disease. But people who have two copies of this most damaging variant have a 30 to 40% higher risk of heart disease than individuals who carry no copies.

However, the second study, led by scientists at deCODE genetics Inc., an Icelandic biotechnology company, cited 60 percent raised risk for heart attack compared to non-carriers.

"This is one of the most significant genetic risk factors found to date for heart attack," said Dr. Kari Stefansson, chief executive of Reykjavik, Iceland-based DeCode Genetics, which is famous for its gene-hunting prowess. "Early-onset heart attacks unexpectedly take the lives of young people, and these are the heart attacks that are most important to prevent. If we can identify the risk factors, we have ways of dealing with the problem."

Researchers from the biotech company deCODE hopes to develop a test for the gene variant that would enable doctors to assess patients at risk more accurately and to recommend early interventions like cholesterol-lowering statins and methods to reduce blood pressure. Heart disease is the leading cause of death worldwide.

The new heart disease risk snip is much less common in Africans and African-Americans and seems not to be correlated with cardiovascular disease in these populations, the US/Canada team reported.

Besides the well-documented effects of smoking, diet and exercise, the twin studies reveal the substantial influence that genetic factors have on the risk of heart disease. The variant of genes increases the risk of cancer by causing cells to multiply speedily, causing a build up of cells in heart blood vessels and eventually causing them to become blocked.

"This is an important finding, because it was replicated in different populations around the world," said Canadian scientist Dr. Ruth McPherson, director of the Ottawa Heart Institute's lipid clinic and lipid research laboratory.

Heart disease is the chronicle affliction in the western world. In the United States alone, some 1.2 million people suffer a heart attack every year and at least 452,000 die from it, as per the data provided by the American Heart Association.