Researchers looking at the genetic sources of schizophrenia say they've identified 83 new chromosome sites on the human genome holding inherited genes linked to the psychiatric disorder.
The finding of the previously unknown genes by international researchers ups the total of known gene variants linked to schizophrenia to 108.
The discovery was made by some 500 researchers working at research institutions in 25 countries that conducted a new analysis of gene samples taken from more than 37,000 people suffering from schizophrenia.
Data from 113,000 people with no evidence of the disorder was analyzed for comparison.
The sites of the newly discovered gene variants were linked to certain brain functions associated with the mental illness, researchers said, including chemical communication among brain cells and pathways dealing with memory, learning and immune function.
"For many years it has been difficult to develop new lines of treatment for schizophrenia, hampered by a poor understanding of the biology of disease," study leader Michael O'Donovan of Britain's Cardiff University says.
"Finding a whole new bunch of genetic associations opens a window for well-informed experiments to unlock the biology of this condition and we hope ultimately new treatments."
The genetic study confirms schizophrenia can have biological origins, similar to other medical conditions, the researcher said.
Although the gene associations can't at present reveal whether a person might or might not develop schizophrenia, the findings could at some point provide a testing tool to identify people at high risk who could benefit from possible preventative treatments, they say.
The total number of genes linked so far to the disorder "only explains about 3.5 percent of the risk for schizophrenia," says Dr. Thomas Insel, director of the U.S. National Institute of Mental Health.
Still, he says, "even based on these early predictors, people who score in the top 10 percent of risk may be up to 20-fold more prone to developing schizophrenia."
The NIMH is a supporter of the Psychiatric Genomic Consortium made up of some 80 research organizations, all of which participated in the study.
"These results underscore that genetic programming affects the brain in tiny, incremental ways that can increase the risk for developing schizophrenia," says Thomas Lehner, head of NIMH's Genomics Research Branch.
Follow-up research with even larger numbers of patients will hopefully help zero in on specific genes and genetic sequences that might present a risk of schizophrenia, the researchers said, and could show the way to new therapies.
