Mass study finds record haul of disease genes

LONDON (Reuters) - The largest ever study of genes in disease has found 24 genetic risk factors -- half of them completely new -- linked to seven common conditions, British scientists said on Wednesday.

It represents the biggest single haul of disease-associated genes so far, underlining an accelerating pace of discovery that will help researchers unpick the fundamental biology of major illnesses and may lead to more effective drugs.

Last week, researchers found a big batch of breast cancer genes and two months ago scientists identified a gene that contributes to obesity.

"We are just scratching the surface," Peter Donnelly of the University of Oxford, who led the Wellcome Trust Case Control Consortium behind the project, told reporters.

"What will happen over the next couple of years, as these sorts of studies are extended, is that our understanding of the genetics of common diseases will change enormously."

Scientists have known for years that genes, along with environmental factors, play a role in increasing the risk that people will develop problems like heart disease.

But they are still trying to work out which parts of the genome -- the 3 billion sub-units of DNA in our cells -- are actually responsible.

To find out more, Donnelly and colleagues from 50 research groups examined 500,000 genetic markers from each of 17,000 individuals, comparing the genomes of diseased and healthy volunteers.

Their findings, published in the journals Nature and Nature Genetics, included the discovery of four new chromosome regions containing genes that can predispose to type 1 diabetes and three new genes for Crohn's disease, the most common form of inflammatory bowel disease.

They also found genetic links to coronary artery disease and hypertension, rheumatoid arthritis, bipolar disorder and type 2 diabetes.

NEW IDEAS FOR TREATMENT

Significantly, many of the genes found were in areas of the genome not previously thought to have been related to the conditions, opening up completely new options for treatment.

In the case of Crohn's disease, they uncovered the importance of a process known as autophagy, or "self eating", which cells use to clear unwanted material, such as bacteria. John Todd of the University of Cambridge said this could be key to explaining the role gut bacteria play in the condition.

Scientists also, for the first time, found a gene linking Crohn's and type 1 diabetes.

The overall increase in risk of disease conferred by the various genetic risk factors was between 1.2 and 1.5 times, suggesting routine testing is not worthwhile.

But Mark Walport, director of the Wellcome Trust medical charity, said there was a clear need for more research in even bigger projects, such as the UK Biobank scheme, which aims to test the DNA of half a million volunteers.