杏吧原创

The microbes that live inside you hint more than your genes do about your likelihood of having health conditions ranging from asthma to cancer and schizophrenia, according to a new analysis.

The finding suggests that monitoring the ecosystems of聽bacteria, viruses, protozoa and聽fungi that live inside us could聽help diagnose or even prevent some conditions. 鈥淭hat鈥檚聽going to change medicine,鈥澛爏ays Braden Tierney at聽Harvard Medical School, who聽worked on the analysis.

However, it also raises privacy issues, because information about this microbiome is currently less tightly regulated than genomic data. 鈥淚f our results are true, that microbiome data聽鈥� which is not private聽鈥� could be telling you a lot more about an individual than even their genetic data,鈥� says Alex聽Kostic at the Joslin Diabetes Center in Boston, who also worked聽on the study. 鈥淲e need to聽rethink data privacy in the age聽of the microbiome.鈥�

Tierney, Kostic and their colleagues analysed 70 previous studies that had linked complex conditions to genetic variants or聽to various aspects of the microbiome, such as the microbe species present. They focused on聽conditions that may be influenced by both genetic and environmental factors, including schizophrenia, Parkinson鈥檚 disease, high blood pressure, asthma and obesity.

For 12 out of the 13 conditions that the team looked at, the microbiome was a better indicator than genetics of whether a person was likely to have a condition. The exception was type聽1 diabetes (bioRxiv, ).

This is the first study to demonstrate that the microbiome is a good indicator of conditions that may be shaped by our environments. This makes sense, because the balance of organisms in our microbiomes is influenced by a range of factors, including our age, diet, exercise regimes and the medications we take.

鈥淎t first, I was very surprised,鈥� says Kostic. 鈥淏ut now it鈥檚 like duh, of course it鈥檚 stronger. The microbiome is constantly changing, the genome isn鈥檛.鈥�

The findings show the need for a holistic approach to predicting health that takes both the genome and the microbiome into account, says Harriet Schellekens at University College Cork, Ireland. 鈥淵ou can鈥檛 look at one over the聽other in isolation.鈥�

In most cases, alterations to a person鈥檚 microbiome are likely to聽be caused by changes in their聽health or lifestyle. But in聽some cases, an altered microbiome may聽be directly involved in聽causing a condition.

Three types of bacteria have been implicated in causing colon cancer, for example. In cases where microbes are to blame, treating the microbiome may prevent certain conditions developing. 鈥淭hat鈥檚 really the聽dream,鈥� says Tierney.

But much more research is needed. We don鈥檛 know yet which features of the microbiome are most informative. This could include which microbes are present and how abundant each聽of聽them are, or which genes they聽have. Long-term studies are聽also needed to reveal how microbiomes change over time.

Microbiome studies typically involve just hundreds of people. We need to study hundreds of聽thousands of people to get better results, says the team.

Studies may now also need to take participants鈥� privacy more seriously. There is a potential exposure of privacy in ways people might not expect, says Tierney.

Currently, in the US, anyone can聽sign into the National Center聽for Biotechnology Information and download stored聽microbiome data that has聽been collected for research.

There is probably little reason to聽be concerned about privacy for聽now, says Matt Jackson at聽the聽University of Oxford. 鈥淚t聽would be a lot of work to have聽a聽vague guess at someone鈥檚 chances of having a disease.鈥�

But it could become a concern as more studies are done and the聽predictive power of the microbiome grows, says Jackson. What鈥檚 more, he points out that stool samples always contain human cells that are sequenced along with the microbes. This means that the raw data from microbiome studies contains human genome sequences that could in theory be used to identify individuals. It is regarded as best practice to remove these human sequences from shared data, but聽this isn鈥檛 always done.

In principle, microbiome data that is identifiable should be regarded as personal data under the European Union鈥檚 data protection laws and subject to the same restrictions, says Alison Hall at the PHG Foundation, a genomics think tank. 鈥淭he test would be whether the microbiome data can聽uniquely identify a person.鈥�