Blood test may flag Crohn's disease risk years before symptoms appear

A study reported that a blood test measuring immune responses to the bacterial protein flagellin was elevated in some people years before they were diagnosed with Crohn's disease, based on samples from relatives in the GEM Project.

Researchers report that a simple blood test detecting immune responses to flagellin, a protein from gut bacteria, was elevated in some people years before Crohn's disease diagnosis. The finding comes from work within the Genetic, Environmental and Microbial (GEM) Project, which has followed first-degree relatives of Crohn's patients since 2008. The study followed 381 relatives, of whom 77 later developed Crohn's disease. The average interval from the blood sample to diagnosis was about two and a half years. Key findings: - The test measured antibodies against flagellin and found higher responses in a subset of people before symptoms appeared. - Among 381 first-degree relatives studied, 77 developed Crohn's and more than 30% of those had elevated antibody responses; responses were strongest in siblings. - The pre-disease immune response was reported to be associated with signs of intestinal inflammation and gut barrier dysfunction, but the study did not map the exact biological steps linking the immune reaction to disease onset and noted limitations. Summary: The study reports an immune marker that appears before clinical Crohn's disease in some people, suggesting a detectable early change in how the immune system interacts with gut bacteria. Researchers announced that further validation and mechanistic studies are underway to confirm these findings and clarify the biological pathway.