Researchers say they hope the identification of one specific gene, that when damaged or mutated increases the risk of schizophrenia, could help them develop targeted treatments for the psychological disorder in the future.
Schizophrenia is a mental illness that causes serious disruptions to how people think, feel and act.
Patients can suffer psychotic episodes and delusions and, in rare cases, become violent towards themselves or others.
While it is understood to be brought on through a combination of environmental, genetic and psychological factors, the exact cause of schizophrenia is unknown.
Now, a team of international researchers have uncovered a piece of the puzzle, which has been hailed by the Queensland Brain Institute as a significant discovery.
Tarjinder Singh, the lead author of the paper from the Wellcome Trust Sanger Institute in Britain, said they had completed the largest analysis of individuals to date.
“After looking at the genomes of over 16,000 people, we were able to implicate single letters in one gene that contribute to significant risk of giving you schizophrenia,” Mr Singh said.
“So we’re estimating close to 35 times the risk.”
Single-letter change to the gene can increase risk
Mr Singh said a mutation to the SETd1a gene, while extremely rare, had been identified as a culprit.
“This is a really rare mutation, it is rarely seen in a general population ever, even in people with schizophrenia, it’s only seen in one every [1,000].”
Mr Singh said single-letter changes that disrupt the gene can greatly increase the risk of schizophrenia.
“Disruptions to this gene are only seen in a very small number of people with schizophrenia,” he said.
“So there’s much more to be learned about the biology suggested by this gene, and so by finding more of these genes and looking for new pathways that are suggested by them, hopefully that will give us informed leads, it will lead to more effective treatment.”
Professor John McGrath, from the Queensland Brain Institute at the University of Queensland, said it was a significant discovery.
“We’ve known for a long time now that genetic factors can increase a lot of mental disorders, like depression and anxiety, and also schizophrenia, which is a very serious and poorly understood group of disorders,” he said.
“And the new study, which is from a very large consortium of many researchers from around the world, have really got their foot in the door for a new pathway.
“They’ve found that a certain gene, if it’s knocked out or missing, increases the risk of not only schizophrenia, but a range of other disorders, so that’s a really interesting finding.”
‘We all carry genes that make us vulnerable’
Professor McGrath said the possibility this research could open up the future of gene therapy was still a distant prospect.
“Very distant future. I think what we’re looking for is treatments to help people with the disorder now,” he said.
“And this particular gene is involved in methylation, which is some of the modifiable aspects of how genes are turned on and off.
“So perhaps, and this is a speculation, if we understand how this gene alters brain development then we may be able to discover better treatments.”
Professor McGrath said what complicated things, was that schizophrenia was not simply a genetic condition.
“That’s pretty much life in modern epidemiology; the most common disorders have a mix of genetic factors and environmental factors,” he said.
“So with respect to schizophrenia, we know that cannabis use increases the risk, childhood trauma, prenatal infection and prenatal nutritional work also increases the risk factors.
“Some of these things are modifiable, but the genetic factors are always there and we’re trying to join the dots to explain why some people go on to get the illness.
“Now just because you have a gene or a variant of [that gene], doesn’t mean you will definitely get the disorder, it increases the risk.
“Just like … things like asthma and diabetes tend to run in families because through no fault of the individual, we all carry genes that make us vulnerable to one or many disorders.
“And this new finding has given us a big new clue to track down what may underlie some types of schizophrenia.”
The study from the Wellcome Trust Sanger Institute has been published in the journal Nature Neuroscience.