Recent research has identified 44 gene loci with significant association to depression. The analysis involved nearly 135,000 people with major forms of depression and more than 344,000 controls. And of those 44 loci found, 30 of them were new discoveries. With the other 14 having been identified in previous studies. That is roughly 70% of the loci being newly discovered. In addition to this, there was also another study done in Nature Genetics. In which they identified 153 genes and also found that depression shared six loci associated with schizophrenia. The study has been described as "a game-changer" by study co-leader Patrick F. Sullivan. The study shows that all people carry genetic variants for depression, but some people's are just higher in volume. Thus resulting in major depression.
There were a number of other findings in this study. Including ways to improve therapies because known antidepressant medications were enriched in the genetic findings. The researchers also found that the genetic basis of depression had overlaps with other psychiatric disorders such as bipolar disorder and schizophrenia. The basis also has overlaps with obesity, daytime sleepiness, insomnia and tiredness. I believe this is important in today's society as depression as become somewhat of a 'silent killer' in the United States. As depression usually leads to suicide. Reducing the affects of depression could save a lot of lives.
Nature Genetics study: https://www.nature.com/articles/s41588-018-0090-3