As part of the study, a team of Australian researchers identified how the activity or expression of those 70 new genes, and 261 other genes that were already linked to mental illnesses, increased the disease risk.“In this study, we are homing in on the biological causes of these mental illnesses,” said Eske Derks, a lead researcher of the study published in the Journal Nature Genetics.
The study was led by the head of QIMR Berghofer’s Translational Neurogenomics Group in collaboration with scientists from Vanderbilt University and the University of Amsterdam.
The researchers examined data from tens of thousands of people collected from four separate studies into schizophrenia, bipolar disorder, depression, and ADHD and compared it to information from hundreds of thousands of healthy controls who were classified as not having mental illnesses.
“For schizophrenia, for example, we looked at the genetic data from about 40,000 patients and compared it to data from about 65,000 control samples from people without the disorder,” Derks asserted.
“Through this process, we identified 275 genes whose activity levels contribute to the risk of schizophrenia, 13 genes whose expression is associated with bipolar disorder, 31 genes involved in depression and 12 for ADHD. We can now conduct follow up tests of those particular genes,” she added.
The study also looked at the DNA and gene activity, or expression, in the brain, colon, adrenal gland and whole blood tissue samples from 700 deceased donors who had not been diagnosed with psychiatric disorders during their lives, to gain an understanding of where in the body the gene activity was taking place.“This study narrows the field on which genes contribute to these four serious mental disorders. Recent studies have found associations between the disorders and large regions of the genome, but they didn’t reveal which particular genes were responsible or how the genes’ activity affected the risk of developing a mental illness,” Derks explained.
“We pinpointed a smaller set of genes and looked at how much their level of expression in different tissues such as the brain, colon, adrenal gland, and blood, contributed to symptoms,” she added.
Derks claimed that this study provides more evidence about the genetic basis of these diseases and by better understanding the biology of the genes, attention can be diverted to finding the best drugs or treatments to manage them.