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Aberrant Genetic Material May Increase Heart Risk in Caucasians |
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Written by Theresa Maher
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Saturday, 05 May 2007 |
A clump of altered genetic material located on chromosome 9 may increase the risk of heart disease in Caucasians by almost 60 percent, two separate studies have found.
Heart disease is one of the leading causes of death globally and was thus far mainly linked to faulty lifestyle habits.
The discovery of aberrant genetic material promises to allow doctors to screen at risk individuals and allow for life-saving interventions early on. Heart disease is manageable if diagnosed in initial stages. Minor lifestyle changes can extend survival by many years.
The newly discovered gene variants are thought to be present in about half the people of European descent, who carry one copy of it. Two copies are present in 20 percent of the people, the report said.
The two reports, published in the online edition of the journal Science, said people with one copy have a 15 to 20 percent increased risk of heart disease, while those having two copies of the genetic variant have a 60 percent higher risk of heart disease as compared people who do not carry the genetic variants.
The finding of genetic basis for heart disease follows the discovery of several genes linked to diabetes last week. These findings are attributed to the hugely successful Human Genome Project.
In the first study conducted by Icelandic company DeCode Genetics and involved 17,000 heart patients as well as healthy volunteers based in Europe, the United States and Iceland. The study did not pinpoint specific genes, but pointed to areas on the DNA where variations called "single nucleotide polymorphisms" (SNPs) took place.
These SNPs are DNA sequence variations that occur in a single nucleotide on the DNA. For example a SNP can be described as an altered genetic code for the DNA, which contains A,T,C,or G units. The Human Genome Project says that SNPs are considered only if present in at least 1 percent of a given population.
The DeCode Genetics team, led by Kari Stefansson found a SNP called rs10757278 as having the ability to increase heart disease risk in Caucasian individuals. "What we've found is a very significant risk factor for the most common cause of death in our society," Stefansson said. "The most important story is that not only does this variant impose the risk of heart attack, but it imposes greater risk on younger people."
The researchers said the presence of the identified SNP doubled the risk of heart attacks in men under the age of 50 and women under the age of 60. People carrying this SNP had a 60 percent raised risk for heart attack as compared to those who did not have the SNP.
The second study led by Canadian researchers examined the DNA of 23,000 heart patients and healthy volunteers in Canada, Denmark and the United States. They identified two SNPs -- rs10757274 and rs2383206 as being implicated in increasing heart disease risk. People carrying these two SNPs had a 30 percent to 40 percent increased risk of heart disease.
"This is an important finding, because it was replicated in different populations around the world," said lead Canadian scientist Dr. Ruth McPherson.
However both teams were unable to explain how these SNPs impacted heart risk. Dr McPherson said the main mystery was that they do not involve genes rather they elaborate aberrant genetic material.
"They may be in a region that regulates the activity of genes," McPherson said. "It is possible that the region regulates genes that are a bit further away. But the finding so far does not tell us anything about their mechanism of action."
The DeCode team is planning to introduce a test that can detect people carrying the faulty SNPs. Stefansson said the company was planning to launch the test on its own.
According to the American Heart Association around 8 million Americans will have a heart attack each year. Major risk factors include age, smoking, heredity, high blood pressure, high cholesterol levels, diabetes and obesity.
Till date genetics was considered a marginal factor in the development of heart disease, but the two studies say it may play a more important role than previously thought. Overall maintaining a healthy lifestyle and avoiding all risky habits will help in preventing heart disease.
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