Figure 1. Illustration of a section of the intestinum tenue showing inflammation of the intestine wall caused by Crohn disease.
Over 200 unique loci for Crohn disease have been identified in large-scale genome-wide association studies. Sequences in the NOD2 gene, the IL23R gene, and the ATG16L1 gene, all involved in innate immunity and epithelial barrier regulation, create vulnerability to Crohn disease. To date, however, no single variant is diagnostic of the condition.
Certain genetic variants are associated with distinct Crohn disease phenotypes. The presence of NOD2 variants are associated with early disease onset and suggest a more complicated disease course, including ileal involvement, stenosis, penetrating disease, and the need for surgery.
The incidence of susceptibility genes varies widely by race and ethnicity; for instance, NOD2 and IL23R variants occur very infrequently among East Asian populations. NOD2 and ATG16L1 appear to have no role in Crohn disease in East Asian populations; ATG16L2, identified in Korean populations, is not associated with Crohn disease in European populations.
Learn more about the etiology of Crohn disease.
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Cite this: Jaime Shalkow. Fast Five Quiz: Diagnosis of Crohn Disease - Medscape - Jan 12, 2022.
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