Researchers ID Genes for Some Common Diseases

WEDNESDAY, June 6, 2007 (HealthDay News) -- In the largest study to date of the genetics of diseases, researchers say they've substantially increased the number of genes believed to play a role in the development of common illnesses, ranging from bipolar disorder to diabetes.

Many of these genes were found in areas of the human genome not previously thought to be related to the diseases, the researchers said. While much was already known about genetic-based diseases, such as cystic fibrosis, little was known about the genetic components of more common diseases.

"These are like heart disease, schizophrenia, depression and arthritis, where we have known that genetics plays a role, but we haven't been able to pinpoint the genetic factors which are involved," said lead researcher Peter Donnelly, of the Department of Statistics at the University of Oxford in England. "Our study is a new dawn to understanding genetic components of common diseases.

"For most common human disease, despite hundreds of years of research, we know depressingly little about what causes them," added Donnelly, who is also chairman of the Wellcome Trust Case Control Consortium. "The big hope with genetics is to give us a new foothold on a new way to understanding the biology of these diseases."

Donnelly noted that a number of approaches had been tried to identify genes connected to common diseases. "There have been a small number of successes but not as good as we would have hoped," he said.

Now with new technologies, only available in the past two years, researchers have been able to do "gene associations studies," which have made linking genes to diseases possible, Donnelly said.

"It is very clear that these studies work," he said. "As a consequence, our understanding of common human diseases is about to change very substantially."

For the new research, the study authors concentrated on seven diseases and found genetic links for each one. These are bipolar disorder, Crohn's disease, coronary heart disease, hypertension, rheumatoid arthritis, and type 1 and type 2 diabetes.

"Six months ago, we probably knew about 10 different genetic risk factors across those diseases," Donnelly said. "We now know closer to 30, and I would expect in a couple of years time, for those diseases, there will be substantially more as there will be for many other common diseases," he said.

Identifying genetic risk factors for diseases opens the door to testing people to determine who's at risk for what illness, Donnelly said. These risk factors, however, do not mean that one is destined to get the disease. "It's predictive, but it doesn't determine one way or the other," he said.

But knowing the risk could help people to take steps to reduce their risk, such as having more frequent screening tests or changing their lifestyle to reduce the risk, Donnelly said.

Also, knowing the biology of common diseases would make it possible to develop new treatments that target their causes, he said.

Donnelly said that even for the diseases the researchers studied, there are likely more genetic components involved than the ones they have found so far.

The researchers are continuing their work and looking for genetic components of tuberculosis, breast cancer, autoimmune thyroid disease, multiple sclerosis and ankylosing spondylitis, a rheumatic disease of the spine.

The findings on the new research are published in the June 7 issue of the journals Nature and Nature Genetics.

Anne M. Bowcock, a professor of genetics at Washington University School of Medicine and author of an accompanying editorial in Nature, said knowing the genetic components of common diseases will dramatically change the way medicine is practiced.

"This is a tour-de-force," Bowcock said of the new research. "It's going to revolutionize medicine."

"Once you know which genes are involved, you will know a lot more about the disease," she said. "There will be novel drugs developed to treat these diseases on the basis of the information that has been found right now."

Bowcock added that knowing the genetic components of a disease will also lead to individualized medicine, where treatments are based on one's own risk for an illness.

More information

For more on genes and disease, visit the U.S. National Center for Biotechnology Information.