When a new baby is born, family and friends cannot resist guessing whom the infant takes after: whether she has inherited blue eyes from her mother, or whether his nose looks exactly like his father’s. The DNA we inherit from our parents influences how we look, of course, as well as our risk of certain diseases, and our cognitive abilities. But DNA influences even more than that.
According to a new study published in the journal Cell Host & Microbe, genes also influence the community of microorganisms that live in the gut: they play a role in what type and amount of bacteria we have in our intestine.
“We set out to find about human genes that are implicated in the regulation of the gut microbiome, and we found some that are”, states senior author Ruth Ley, an Associate Professor in the Department of Microbiology at Cornell University, in a press release.
The study, led by Cornell University researchers, provides the strongest evidence yet that human DNA shapes the constituency of gut microbiota. And also it identifies some heritable species linked to diet preference, metabolism or the immune system.
For instance, researchers found that people who have some specific variants of the gene LCT, which influences whether people can digest lactose (sugar contained in milk and other dairy products), have more Bifidobacterium in their guts; these are ‘friendly’ bacteria commonly used in probiotics. Also, researchers observed some links between specific genes, gut bacteria, and blood pressure. This complicates the picture of what it means to inherit these things genetically, since changes in both genes and gut bacteria occur together.
“Our genes might influence which microbes persist in the gut and which are more dominant than others,” explains Julia Goodrich, doctoral student and National Science Foundation Graduate Research Fellow in Ley’s lab, in a press release. “Diet also influences the microbiome, and our genetics can even influence our diet preference and taste perception. They all seem to be interrelated, and our genes impact which microbes thrive inside us to a degree we didn’t know until recently.”
In all, scientists identified more than a dozen microbes with known links to health that are heritable.
To come to these conclusions, the investigators used genome information from 1,126 pairs of identical and fraternal twins from the Twins UK Study, held by King’s College in London. These sibling pairs had already had their genomes analysed and there were 1.3 million small genetic variations known for each participant.
Researchers then conducted studies of the siblings’ fecal samples to determine how similar the gut bacteria were among twins genetically identical versus fraternally related and raised in the same environment. They observed that the host’s genes shaped 8.8% of the microbes.
“These microorganisms are environmentally acquired but the genome also plays a part, by determining which microorganisms are more dominant than others”, says Ley.
Julia K. Goodrich, Emily R. Davenport, Michelle Beaumont et al. Genetic Determinants of the Gut Microbiome in UK Twins. Cell Host & Microbe, 2016; 19 (5): 731 DOI:10.1016/j.chom.2016.04.017