This isn't about to usher in a cure or treatment. Scientists haven't yet found a way to turn genetic findings around mental illness into practical solutions. It could get the ball rolling, however, and will at least help explain how major depressive disorder works. And as 23andMe is more than a little eager to point out, it's a testament to how large-scale, customer-submitted genomic data can lead to answers that might be difficult to obtain through conventional studies.