The CONVERGE consortium has identified the first genetic risk loci for depression.

Genetic risk factors for major depressive disorder have been surprisingly hard to pin down, with several major genomewide association studies coming up empty. One theory is that genetic associations are drowned out by the extreme heterogeneity of the disease, which may consist of environmentally caused cases, and mild and more severe cases that may have distinct genetic risk factors.

In their study, the consortium decided to increase the chances of detecting a genetic association by focusing on a genetically relatively homogenous population of about 5,000 Han Chinese women. Furthermore, only those with relatively severe depression were genotyped.

Using that approach, the authors were able to identify two risk-associated variants, one near the SIRT1 gene and the other in an intron of the LHPP gene. The authors said that "we attribute our success to the recruitment of relatively homogeneous cases with severe illness."

They reported their finding in the July 30, 2015, issue of Nature.

LOOK TO THE GUT TO DIAGNOSE RA

In separate science news, a team from the Chinese Beijing Genomics Institute – Shenzhen has shown that individuals with rheumatoid arthritis (RA) had altered oral and gut microbiomes, and that the specific nature of the changes predicted their response to drugs.

The signature pathology in rheumatoid arthritis is joint inflammation, but inflammation in other parts of the body can, in fact, develop years before the onset of clinical symptoms in RA patients. In their work, the authors looked at the gut, salivary and dental microbiomes via metagenomic sequencing and found that alterations in all three correlated and could be used to stratify patients on the basis of their response to therapy.

The authors concluded that "our results establish specific alterations in the gut and oral microbiomes in individuals with RA and suggest potential ways of using microbiome composition for prognosis and diagnosis."

They published their results in the July 27, 2015, online issue of Nature Medicine.

Editor's note: These are outtakes from BioWorld's Bench Press, a weekly addition to the daily news in which BioWorld takes a look at translational medicine. For more science news like this, look for the attachment every Monday morning, or visit BioWorld's dedicated science portal, The BioWorld Biome: Our Habitat for All Things Science at www.bioworld.com.