Scientists announced on Monday that they had pinpointed 15 locations in our DNA that are associated with depression, one of the most common mental health conditions and one that is estimated to cost the world billions in health-care costs and lost productivity.
Although gene association studies — which link DNA inherited from our parents to particular diseases, conditions or even habits such as vegetarianism — are published practically every week, this is a particularly important one. It's the first large study on major depressive disorder in people of European descent, and it shows that the genes that may be involved in the condition correspond to those involved in the development of neurons in the brain. There is also overlap between the genetic regions implicated in depression and those that have been linked to other psychiatric disorders such as schizophrenia. This finding supports another key study published in April that focused on genetic factors related to well-being and depression, which found that the genetic variants for those genes had some "moderate" overlap with those with schizophrenia and bipolar disorder. This may suggest that scientists study these genes and traits jointly in future work.
The new study, published in Nature Genetics, involved an analysis of genetic variations of 75,607 people of European ancestry who self-reported having depression and 231,747 healthy controls.
The results are unlikely to lead to any new treatments anytime soon. People have been discovering genes associated with mental illness for decades but haven't figured out how to translate that into ways to help people. Moreover, many scientists think that environmental factors play just as important a role as genetics in the development of depression, so eliminating someone's risk of depression isn't as simple as, say, gene therapy might be for conditions that are controlled by one or two genes.
“We hope these findings help people understand that depression is a brain disease with its own biology,” said Roy Perlis, associate director of the psychiatric genetics program in mood and anxiety disorders at Massachusetts General Hospital. “Now comes the hard work of using these new insights to try to develop better treatments.”
The other noteworthy thing about this study, conducted by researchers from Massachusetts General Hospital and the University of Pennsylvania, is that the data came from people who sent their saliva to Silicon Valley personal genomics company 23andMe and consented to allow the company to use that information (anonymously) for research.
The decision to open up the company's data and collaborate with outside researchers is one of the most important decisions that 23andMe founder Anne Wojcicki made when she started the company and one that has made the modest-size Silicon Valley venture one of the most important players in the field of genetics.
For many years, a number of research groups have been trying to create their own large databases of DNA data and have had trouble getting their efforts off the ground. George Church created the Personal Genome Project in 2005 at Harvard Medical School to serve as a publicly shared resource on people's genetic makeup and health, but there have been only a limited number of volunteers. Craig Venter, the rogue scientist who competed with government-supported scientists to sequence the first human genome, started a venture a few years ago that aims to collect and analyze comprehensive genetic and microbial data on millions, but it is still far from that goal. National Institutes of Health Director Francis Collins recently announced that the government is seeking to create a genetic database of 1 million people, but details are still being sorted out.
It's possible, perhaps even likely, that the world's pharmaceutical giants have genetic data for patients on the scale of 23andMe, but for the most part they don't talk about it, and they certainly don't share it with academic researchers outside of the companies' own clinical trials.
In contrast, 23andMe has created a whole division to work with academic researchers.
Although the information that 23andMe houses is vast — more than one million customers have consented to research participation, 450,000 for the most recent study — the data isn't perfect. It's based on saliva rather than blood. Saliva is believed to be less reliable because of the naturally degrading enzymes and bacteria in it. The company also doesn't run a full genome sequence but looks only at certain key points in the genome.
But for now, it's the best we have, and we're learning a lot nonetheless. In recent years, the company has published a huge number of groundbreaking studies on how our DNA might influence important health issues, such as our susceptibility to migraines and age of onset of puberty, as well as things we weren't sure were genetic in the first place, such as educational attainment and even whether we're morning people or night owls.