Researchers have identified mutations in genes that control epigenetic regulation, which may contribute to both schizophrenia and autism.
Schizophrenia affects about 1% of the adult population. Currently, schizophrenia can only be diagnosed by observing behavior and measuring the duration of the symptoms and functional impairment. There is little biological understanding of the disease, which has presented a barrier in developing more precise diagnosis and more effective treatments.
As schizophrenia can be inherited and because genomic technologies have vastly improved in recent years, research has now turned to investigating the genetic risk factors for the condition.
Previous research in this area has provided estimates for about a quarter of the genetic contribution to schizophrenia risk, and has revealed a genetic risk overlap with some other psychiatric disorders, such as bipolar disorder.
Also, past research has found that some genetic variants are implicated in autism, intellectual disability and seizure disorder, as well as schizophrenia.
To further explore this link, and as part of a collaboration between Trinity College in Dublin, Ireland, and Cold Spring Harbor Laboratories (CSHL) in New York, a team of researchers performed genetic sequencing on 171 Irish people who have at least one schizophrenic family member.
New genetic mutations identified
Analyzing the sequences, the team identified new genetic mutations that were present in people with schizophrenia, but not in their unaffected parents. This means that the mutations were new and not inherited.
The team identified new genetic mutations that were present in people with schizophrenia but not in their unaffected parents. This means that the mutations were new and not inherited.
First author, Shane McCarthy of CSHL, says: "We found that these types of mutations occurred more common than expected in people with schizophrenia and are likely to have functional consequences."
"Such things can happen by chance, and we are all likely to carry a small number of apparently damaging mutations with no obvious health consequences," senior author, Trinity College's Prof. Aiden Corvin, told Medical News Today.
However, Prof. Corvin, further explains:
"Two things were of interest in this study, first that the genes where this was happening (AUTS2, CDH8, HUWE1) had already been implicated in autism and intellectual disability. When we tested whether this was a chance clustering we found this to be highly unlikely. Second, the genes appear to be involved in the same process, which is to control how DNA is used, or expressed as proteins. So they seem to be regulatory."
What this means is that the genes have a common function - called chromatin modification - in regulating how other genes function. Prof. Corvin thinks that chromatin modification "may be an important molecular mechanism in explaining how developmental disorders of this type emerge."
He adds that this process can be targeted by some treatments, so the team's goal now is to further investigate this at a cellular level.
"I believe that treatments will emerge which target the underlying molecular problem," he says, "rather than is the case now, the clinical diagnosis of autism or schizophrenia."
Prof. Corvin concludes:
"This is a really exciting finding as it suggests that neurodevelopmental disorders such as schizophrenia and autism, which hitherto have been seen as different diseases may involve common underlying disease mechanisms. This may have implications in the future for how we conceptualize and treat these conditions."
In 2013, Medical News Today reported on a study published in The Lancet that found four risk gene mutations common to bipolar disorder, attention deficit-hyperactivity disorder, autism, major depressive disorder and schizophrenia.