What the Cell: Adventures in Science

Mendelian randomization is a research method used in epidemiology to estimate the effects of a causal variable without conducting a clinical trial – it reduces reverse causation and confounding. It is important in genetic research because, despite the abundance of genetic data available, much of it is summarized at high levels that don’t allow you to drill into race, sex, and other dimensions which are often confounders.

The study found that Eubacterium ruminantium is associated with a lower risk of endometriosis, while Anaerotruncus, Olsenella, and Oscillospira were associated with a higher risk of endometriosis. Additionally, they found that triglycerides partially mediate the effects of Olsonella on endometriosis but only account for 3.3% of the effect.

Issues with this study

• No actual microbiome data was analyzed – they measured genetic predisposition to high levels of the above bacteria. They did not collect stool samples from endometriosis patients and culture them.
• Did not conduct multiple testing corrections for p values, used < 0.05