Genetic breakthrough may pave way to new heart and stroke tests

Scientists have found the largest number of genes associated with an increased risk of developing heart disease in a study that helps to pave the way towards the day when doctors may be able to offer genetic tests that can identify people most at risk of heart attacks and strokes.

The genetic basis of heart disease is well established – it explains why some people live long lives despite unhealthy lifestyles while others die young – but it is only through decoding the human genome that scientists have been able to start pinpointing the actual genes involved.

In one of the biggest studies so far, involving 140,000 people from the US, Iceland, Britain and the rest of Europe, scientists have identified 13 genetic mutations out of the 3 billion-long sequence of "letters" in the human genome, that each confer a small but significant increased risk of coronary heart disease.

People who inherit a particular combination of these genetic variations, called single nucleotide polymorphisms, may be at higher-than-average risk of developing heart disease, especially if they adopt an unhealthy lifestyle, such as a fatty diet and no regular exercise.

The scientists behind the study, published in the journal Nature Genetics, believe that the breakthrough will help to identify the genes that are involved in, for example, the build-up of fatty deposits inside the walls of coronary arteries which leads to atherosclerosis and heart disease.

"These new discoveries will allow scientists worldwide to eventually better understand the root causes of coronary atherosclerosis, possibly leading to important new drug therapies that may profoundly reduce the risk of having a heart attack," said Professor Thomas Quertermous of Stanford University in California.

"We've been slow in understanding the molecular pathways associated with the disease process in the walls of blood vessels. Studying the function of the genes in these gene regions should teach us how we can block the process of plaque development in the vessel wall. Currently there are no drugs that directly target the vessel wall," Professor Quertermous said.

In order to find the genetic mutations, the scientists had to compare the entire genomes of people with and without heart disease, a process akin to looking for a needle in a haystack.

"Out of the roughly 3 billion bases in our DNA code, we're talking about finding a few bases that are different in some people, and that difference leads to a change in the function of a gene or a set of genes that in turn changes your lifetime risk of having heart disease," Professor Quertermous said.