The investigators analyzed the gut microbiomes of 1,126 pairs of twins who were part of the TwinsUK Study. This multiyear research effort, which includes a total of 12,000 twins, is looking at a number of diseases and conditions. By including data from both identical and fraternal twins who were raised together, the study seeks to account for both environmental and genetic contributions.

The twins in the current study had already had their genomes analyzed, and 1.3 million small genetic variations (also known as single-nucleotide polymorphisms or SNPs) were known for each participant. The investigators used the genome-wide association approach to look for connections between genetic variations between twin pairs and certain bacterial types that were present and stable in the study subjects.

The analysis confirmed earlier findings that several other types of bacteria are also heritable, but specific genes connected to those differences were not found. One connection they were able to make was between the lactate (LCT) gene, which is involved in making the enzyme that helps the body digest dairy, and a type of microorganism called Bifidobacterium, which is commonly used in probiotics.
 
Authors also identify an association between the host gene ALDH1L1and the bacteria SHA-98, suggesting a link between formate production and blood pressure. Additional genes detected are involved in barrier defense and self/non-self recognition. These results indicate that diet-sensing, metabolism, and immune defense are important drivers of human-microbiome co-evolution.

http://www.cell.com/cell-host-microbe/fulltext/S1931-3128(16)30153-6