A large genetic analysis suggests that inflammatory bowel disease (IBD), especially Crohn’s disease, and primary biliary cholangitis (PBC) are biologically connected, while ulcerative colitis appears to follow a different path, according to results from a study published recently in Medicine.
Using genetic data rather than patient history, researchers found evidence that Crohn’s disease increases the risk of developing PBC, and that genetic risk for PBC can also raise the risk of IBD overall.
The study used a method called Mendelian randomization, which relies on inherited genetic variants to explore cause-and-effect relationships. Researchers analyzed genome-wide association data and selected single-nucleotide polymorphisms strongly linked to IBD, Crohn’s disease, ulcerative colitis and PBC. Multiple statistical approaches were applied to ensure the findings were reliable and not due to chance or hidden bias.
Genetically predicted IBD was associated with a 20% higher risk of PBC; Crohn’s disease showed a similar pattern. In contrast, ulcerative colitis did not show a statistically significant relationship with PBC.
Read more about causes and risk factors for PBC
When the analysis was reversed, genetic risk for PBC was linked to a higher likelihood of IBD overall. However, there was no clear evidence that PBC caused Crohn’s disease or ulcerative colitis individually. Extensive sensitivity testing showed no major signs of bias or distortion in the results.
For patients, these results do not mean that having Crohn’s disease will inevitably lead to liver disease. Instead, they suggest that some people may share underlying immune or genetic traits that affect both the gut and the liver. Researchers point to the gut-liver axis, where intestinal inflammation can expose the liver to immune triggers, while bile acids from the liver influence gut bacteria and immune responses.
Understanding these shared pathways may eventually help doctors identify patients at higher risk and monitor symptoms earlier. While more research is needed before changing care, the results offer reassurance that ulcerative colitis does not appear to carry the same genetic link to PBC, and they highlight why Crohn’s disease may warrant closer attention to liver health over time.
“These findings can significantly contribute to the advancement of the diagnosis and treatment of both IBD and PBC,” explained the study’s authors.
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