Scientists at Cold Spring Harbor Laboratory in collaboration with colleagues at the University of Washington and the National Institute of Mental Health found that deletions, disruptions and duplications of normal genes were three to four times more frequent in people with schizophrenia, NIMH said Friday in a release.

Rare mutations showed up in only 5 percent of the healthy people in the study vs. 15 percent of those with schizophrenia. The rate of rare mutation was 20 percent among patients who had developed schizophrenia before age 19.

"This part of our findings indicates something we didn't know before: that rare structural mutations in genes, while present in both healthy people and people with schizophrenia, are much more likely to occur among people with the illness," said senior author Jonathan Sebat of Cold Spring Harbor. "This suggests a previously unknown role for rare mutations in the causation of schizophrenia."