Genetic makeup influences the gut microbiome

 The statement "we are what we eat" will have to be slightly modified, according to a recent study by King's College London and Cornell University, which suggests that our genetic makeup influences whether we are fat or thin, through the regulation of what types of microorganisms live in our body.

Both the genetic makeup of an individual and the microbial populations of the intestine can influence metabolic disease or obesity, but so far the relationship between the two or how genetic changes can shape or interact with the microbiome and this affect the phenotype, it was not clear.

Among the members of the same family, the microbiome is more similar than between unrelated people, however, although this characteristic could be due to the fact that they share a greater proportion of genetic identity, traditionally, this was attributed to the shared environment and the common diet.

In order to determine which species of the microbiome are heritable and to what extent they are and how these species are related to the rest, the researchers carried out a study in which they compared the microbiome of pairs of identical twins, which share their composition genetics and non-identical twin pairs that share on average 50% of their genetic architecture. In total, the team analyzed more than 1,000 fecal samples, corresponding to more than 400 pairs of twins, and found that the abundances of some of the microbial populations were more similar among identical twins than non-identical twins. Specifically, the family of bacteria whose presence is most influenced by the genetic makeup of their host is the Christensenellaceae family.. As this is a recently described family, the type of interaction between it and the host is unknown. However, this family, and those other species with which it interacts, were found enriched in individuals with a low body mass index.

Finally, in order to analyze the phenotypic effects of the Christensenellaceae family , the researchers used fecal transplants in mice free of these bacteria and observed that after transplantation and incorporation of the bacteria in the intestine, the mice lost weight.

Los resultados obtenidos proporcionan, por primera vez, evidencias de que la abundancia de algunas especies de bacterias, no sólo está influida por condiciones ambientales como la dieta, el estilo de vida o la salud, sino que también está condicionada parcialmente por la genética del hospedador y que la variabilidad de estas poblaciones bacterianas entre las distintas personas se debe en parte a la variabilidad genética de las personas. Además, las evidencias de que ciertas especies microbianas en el intestino, cuya abundancia está influida por los genes, pueden ser protectoras para la obesidad, convierten al microbioma en una atractiva diana para los tratamientos destinados a combatir la obesidad.