Analysing a person's stool microbes can help quickly and easily diagnose liver cirrhosis, a team led by an Indian-origin scientist has found.
It is difficult and invasive to detect liver cirrhosis before it is well advanced, according to the study published in the journal Nature Communications.
In an effort to identify people at high risk for nonalcoholic fatty liver disease (NAFLD)-cirrhosis, researchers at the University of California San Diego in the US identified unique patterns of bacterial species in the stool of people with the condition.
"If we are better able to diagnose NAFLD-related cirrhosis, we will be better at enrolling the right types of patients in clinical trials, and ultimately will be better equipped to prevent and treat it," said Rohit Loomba, a professor at UC San Diego School of Medicine.
"This latest advance towards a noninvasive stool test for NAFLD-cirrhosis may also help pave the way for other microbiome-based diagnostics and therapeutics, and better enable us to provide personalised, or precision, medicine for a number of conditions," Loomba said in a statement.
The precise cause of NAFLD is unknown, but both diet and genetics play substantial roles, researchers said.
Up to 50 per cent of obese people are believed to have NAFLD, and people with a first-degree relative with NAFLD are at increased risk for the disease themselves, they said.
In a previous study of patients with biopsy-proven NAFLD, Loomba and colleagues found a gut microbiome pattern that distinguished mild/moderate NAFLD from advanced disease, allowing them to predict which patients had advanced disease with high accuracy.
In this latest study, Loomba's team wanted to know if a similar stool-based "read-out" of what is living in a person with NAFLD's gut might provide insight into his or her cirrhosis status.
The researchers analysed the microbial makeup of stool samples from 98 people known to have some form of NAFLD and 105 of their first-degree relatives, including some twins.
They did this by sequencing the 16S rRNA gene, a genetic marker specific for bacteria and their relatives, archaea.
The 16S rRNA sequences serve as "barcodes" to identify different types of bacteria and the relative amounts of each, even in a mixed sample like stool.
The researchers first noticed that people who share a home also tended to share similar microbial patterns in their gut microbiomes, further validating several previous studies.
In addition, they observed that people with extreme forms of NAFLD had less diverse and less stable gut microbiomes.
The team identified 27 unique bacterial features unique to the gut microbiomes, and thus stool, of people with NAFLD-cirrhosis.
The researchers were able to use this noninvasive stool test to pick out the people with known NAFLD-cirrhosis with 92 per cent accuracy.
However, more importantly, the test allowed them to differentiate the first-degree relative with previously undiagnosed NAFLD-cirrhosis with 87 per cent accuracy. The results were confirmed by magnetic resonance imaging (MRI).
While Loomba estimates that a stool-based microbiome diagnostic might cost USD 1,500 if it were on the market today, he predicts that cost will lower to less than USD 400 in the next five years due to advances in genomic sequencing and analysis technologies.