Almost 700,000 people in the U.S. suffer from Crohn’s disease however each individuals experience with the chronic illness is unique and can differ significantly from others. For some individuals, flare-ups only occur every few years, others may never get relief and ultimately require surgical intervention.¹ New research may explain why the disease affects people differently.² 

Crohn’s dis­ease and ulcerative colitis (collectively called inflammatory bowel disease, or IBD) result from a hyper­active immune system that attacks the gastrointestinal system. The immune system’s attack leads to inflammation of the intestines caus­ing abdominal pain, diarrhea, rectal bleeding, and other symptoms. Immunotherapies for IBD aim to suppress the excessive, inappropriate immune response that is causing the inflammation.

The cause of Crohn’s disease is not known, but the disease is associated with abnormalities of the immune system that could be triggered by a genetic predisposition or diet and other environmental factors. There is currently no cure for Crohn’s disease.¹

While the exact cause of Crohn’s is not well defined, researchers have established that certain genes and the presence of some types of gut bacteria are linked to a person’s risk of developing the disease.  James Lee, a gastroenterologist at University of Cambridge is the author of a new genetic analysis of people with Crohn’s. He and colleagues analyzed the whole genome of 2,734 individuals with Crohn’s, and identified four genes that appear to influence the severity of a person’s symptoms.  These same four genes had previously been determined to play a role in determining the severity of other chronic immune conditions.²

Importantly, the four genes are specifically associated with the severity of Crohn’s symptoms, not causation of the disease itself. This and the link to symptoms in other chronic inflammatory diseases suggests that if scientists are able to design drugs that work against the specific genetic pathways identified in this study, new therapies could be developed that will be effective for Crohn’s and a range of illnesses.

References:

1. Reference: Dahlhamer JM, Zammitti EP, Ward BW, Wheaton AG, Croft JB. Prevalence of Inflammatory Bowel Disease Among Adults Aged ≥18 Years — United States, 2015. MMWR Morb Mortal Wkly Rep 2016;65:1166–1169. DOI: http://dx.doi.org/10.15585/mmwr.mm6542a3.
2. Lee, JC, Biasci, D, et al. Genome-wide association study identifies distinct genetic contributions to prognosis and susceptibility in Crohn's disease. Nature Genetics; 9 Jan 2017; DOI: 10.1038/ng.3755

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