Researchers at the UNC School of Medicine played key roles in a giant international study that mapped some of the likely genetic underpinnings of schizophrenia, opening the door to new therapies for the debilitating psychiatric disorder.
The study, published online Tuesday in the journal Nature, identified 108 sites in the human genome that are associated with the risk of developing the disorder, which is among the most common – and serious – mental illnesses. Schizophrenia affects millions of people.
Doctors said the potential for new medicines is a particularly important implication, because drugs for schizophrenia have been aimed at the same lone site in the human genome for more than half a century.
“This gives researchers new targets to study which could help identify pharmaceutical or other interventions that could be used on these pathways or systems in the brain,” said Dr. John Gilmore, a professor of psychiatry at UNC who was not involved in the study.
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Gilmore is deeply familiar with the disorder: He is director of UNC Center for Excellence in Community Mental Health, a program for people with schizophrenia and other serious mental illnesses that treats more than 1,000 patients in the Triangle.
The study is the largest ever of the genetics of a psychiatric disorder. It involved more than 300 researchers in nearly 30 countries. They scrutinized genetic samples from nearly 37,000 people who had been diagnosed with the disorder and more than 113,000 healthy adults. Among the locations in human genes that they linked to schizophrenia were 83 that had never before been connected to the illness.
“Every single one of these is a clue, a clue to a gene or part of the genome that might have something to do with schizophrenia, and that’s really cool because that’s the kind of thing that gives us ideas about biology, that will give us ideas about what’s really going wrong,” said Dr. Patrick Sullivan of UNC-CH, a co-author of the research paper and co-founder of the Psychiatric Genomics Consortium, an international group of dozens of institutions and hundreds of researchers conducting broad-scale analyses of genetic data for psychiatric disease.
The study is the result of several years of work by the consortium’s Schizophrenia Working Group.
More than 1 in 100 adults are affected by schizophrenia, which is often characterized by hallucinations, paranoia and inability to engage in normal social behavior. Its societal costs are estimated at more than $60 billion annually in the United States alone.
‘The biggest step’
Even though schizophrenia is a huge public health issue worldwide, science has long struggled to understand its complicated causes.
“Until we can actually come to terms with what that is, it’s going to be very difficult for us to design effective treatments, to really understand what’s going on and how we can keep people healthy,” said Sullivan. “And this project is the biggest step in that direction, I would argue, that we have ever taken.”
Nearly a dozen scientists from UNC-CH participated in the study. Sullivan’s role included helping write and edit the paper. Other UNC researchers’ work on the study included helping design it and recruiting subjects.
‘Many different pathways’
The study clarified that schizophrenia is caused by both genetic factors and environmental factors such as contracting certain illnesses, substance abuse and psychological stress. Many people whose genes were scrutinized had large numbers of the genetic risk factors but didn’t have schizophrenia.
“We label it with one word, but you can probably get to it many different ways, so you might have a certain combination of risk genes and environmental risk factors that lead to schizophrenia,” Gilmore said. “Meanwhile, another person may have a completely different set of both, and also get schizophrenia, so there are probably many different pathways to developing it.”
That means that one day researchers may be able to identify subtypes of the disorder, which could then be targeted with more specific treatments, he said.
“Perhaps in the future we’ll be able to say, well, you’ve got these risk genes, or this pathway is involved in your individual form of schizophrenia, and so these particular drugs might be more effective for you,” Gilmore said.
Most of the sites on the genome that were found to be associated with the disorder were related to brain function. But a particularly intriguing finding was a number of connections between the disorder and genes in the immune system, which had long been hypothesized. That could help lead to better understanding about links to specific illnesses, perhaps in particular viruses that affect the brain, Sullivan said.