A quarter of the risk for developing schizophrenia can be traced to genetic variations that are common in the general population, a study by Queensland researchers has found.
A new method of genetic analysis developed by The University of Queensland’s Queensland Brain Institute, in conjunction with The University of Queensland Diamantina Institute and the Queensland Institute of Medical Research, found that all people carry genetic variants that contribute to the risk of schizophrenia.
But only people who carry many of those variants together are at substantial risk of being affected.
The chronic disorder, characterised by persistent delusions and hallucinations, affects about one person in 100 at some point in their lives and usually strikes in late adolescence or early adulthood.
The latest research into the disease, published in the journal Nature Genetics, has shed light on its elusive genetic underpinnings, said the study leader, Associate Professor Naomi Wray from the Queensland Brain Institute.
“Not long ago people talked about finding "the gene” for schizophrenia, then the “handful of genes”. Our research implies there are many genetic factors acting together, and together with environmental factors,“ Professor Wray said.
“If we all carry some risk variants then our systems are robust to their effects – for example other pathways may compensate. Our results suggest that affected people may carry a burden of risk variants that means compensatory mechanisms can no longer cope.”
The researchers compared genetic variations in DNA known as single-nucleotide polymorphisms across 9,087 people who had schizophrenia and 12,171 people who did not.
They found that 23% of liability for the brain disorder could be traced back to a set of variations, most of which are common in the general population. The variance was shared equally between men and women.
According to Professor Naomi Wray, this suggests that we all carry genetic risk variants for schizophrenia, but that the disease only emerges when the burden of variants, in combination with environmental factors, reaches a certain tipping point.
Cannabis use is recognised as one environmental factor that contributes to the risk of developing schizophrenia.
Paul Fitzgerald, a Professor of Psychiatry at Monash Alfred Psychiatry Research Centre, said the past 10 years of research into schizophrenia had been characterised by “high hopes followed by disappointing results. But this study provides some novel and promising guidelines for how we can understand the causes of schizophrenia and where we go from here.”
The findings suggested that variations in many hundreds of genes contributed to the risk of developing schizophrenia, Professor Fitzgerald said. “Variations in many of these genes, however, are frequently found across all people and will be possible targets for study to help develop new treatments.
“However, before this can occur we need to individually identify this set of genes and this is likely to take studies with up to 50,000 patients and a similar number of controls.”
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Comments (4)
Charlotte LeBlanc
Nutritionist (logged in via email @rogers.com)
I have to agree that we all have schizophrenic genes. Schizophrenia could happen to a large percentage of the population given the right environment. Our family has lived it for 10 years. My son is now well, living a normal life; working, married, and living his passion (music) and medication free! We have written our story to provide hope to families and give another perspective to professionals helping youth deal with schizophrenia. Hope you enjoy it: www.wellnesshealthworks.com
John Harland
bicycle technician (logged in via email @gmail.com)
Thanks for that insight, Matthew.
I have used the concept of damping in the context of mood swings. Rhythmical swings, including mood swings, are part of being a living organism, and part of creativity.
In adverse circumstances, the amplitude of the swing needs to be damped.
It may be a good model for most mental "illnesses".
John Harland
bicycle technician (logged in via email @gmail.com)
What is the benefit of locating these genes? To eliminate them, or to marginalise the people who carry them?
Why have we evolved with these genes? What benefits do they bestow on us in circumstances that do not tip us over the edge into actual schizophrenia?
Matthew Albrecht
(Postdoc at Curtin University)
The benefit of locating these genes is a more targeted focus for therapeutics and a better understanding of the disease in general.
I'm not sure which genes are being talked about here, but one understanding of schizophrenia is that the systems that are tipped over the top are related to attributing importance to stimuli. In most people these act reasonably fine to make sure that important things in the environment (even important thoughts) are paid the amount of attention they are deserved. When…
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