A team of researchers has identified 17 genetic variations associated with depression in individuals of European ancestry.
The team identified 17 new genetic variations linked to depression. Image credit: Patrica J. Joslin.
It’s well known that at least some depression runs in families and some risk is inherited.
Yet, prior to this study, conventional genome-wide approaches had failed to reliably identify chromosomal sites associated with the illness in populations with European roots.
Since depression is thought to be like fever – a common set of symptoms likely rooted in multiple causes – lumping together genetic data from people with different underlying illness processes likely washed out, or statistically diluted, subtle evidence of effects caused by risk genes.
To increase their odds of detecting these weak genetic signals, the team of researchers from Harvard/Massachusetts General Hospital, Pfizer Inc. and 23andMe Inc. adopted a strategy of studying much larger samples than had been used in the earlier studies.
The team first analyzed common genetic variation in 75,607 people of European ancestry who self-reported being diagnosed or treated for depression and 231,747 healthy controls of similar ethnicity.
These data had been shared by people who purchased their own genetic profiles via www.23andMe.com website and agreed to participate in the company’s optional research initiative, which makes data available to the scientific community, while protecting privacy.
The researchers integrated these data with results from a prior Psychiatric Genomic Consortium genome-wide-association study, based on clinician-vetted diagnoses of more than 20,000 patients and controls of European ancestry.
They then followed-up with a closer look at certain statistically suspect sites from that analysis in an independent 23andMe ‘replication’ sample of 45,773 cases and 106,354 controls.
In all, the team found 17 genetic variations linked to depression at 15 genome locations.
In addition to hinting at a link between depression and brain gene expression during development, there was also evidence of overlap between the genetic basis of depression and other mental illnesses.
“While the genome sites identified still account for only a fraction of the risk for depression, the results support the strategy of complementing more traditional methods with crowd-sourced data,” the scientists said.
“We hope these findings help people understand that depression is a brain disease, with it’s own biology,” said lead co-author Dr. Roy Perlis, from the Center for Experimental Drugs and Diagnostics at Harvard/Massachusetts General Hospital.
“Now comes the hard work of using these new insights to try to develop better treatments.”
The team’s results were published online this week in the journal Nature Genetics.
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Craig L. Hyde et al. Identification of 15 genetic loci associated with risk of major depression in individuals of European descent. Nature Genetics, published online August 1, 2016; doi: 10.1038/ng.3623
