Researchers at the University of Washington say they've found specific gene variations linked to schizophrenia. Three rare deletions in the human genome seem to raise the risk of developing the devastating brain disease considerably. In other words people who lack certain chunks of DNA are more likely to develop the mental disease.

Schizophrenia, a serious disorder, is characterized by hallucinations and delusions and affects some 1 percent of the population. It is usually diagnosed in late adolescence or early adulthood and tends to be chronic.

The new work is notable because two large studies independently identified the same two DNA deletions. Both papers were published online Wednesday by the journal Nature.

"Once we understand what the mutations are doing, new drugs and new approaches like preventative measures can be developed. It opens up the way to new methods for classifying and diagnosing people with the illness," said David St. Clair, a psychiatrist at the University of Aberdeen in Scotland who worked on both studies.

In the studies, the researchers analyzed the genes of 6,000 to 10,000 people from around the world, half of whom had schizophrenia. The next step is to find out how these deletions affect brain function, according to the researchers, who included scientists from deCODE genetics in Iceland and the U.S. based Broad Institute of MIT and Harvard Universities in Massachusetts.

Pamela Sklar of the Broad Institute, who led one of the studies, explains: "This work opens up an entirely new way to think about schizophrenia and eventually will suggest avenues for researching therapies for the sake of patients and families suffering from this terrible disorder."