Crohn's disease

More than 30 distinct genes, or presumed locations of genes (loci), have been suggested to be related to CD, including those related to susceptibility, age of onset, disease location, diagnosis, and prognosis.^[1] So far, the strongest associations with CD have been found with the NOD2 (also called CARD15), IL23R and ATG16L1 genes.^[1]

The search for specific susceptibility genes (genes in which variations may increase a person's risk) has been difficult due to complex genetics, including factors such as the lack of simple inheritance patterns and involvement of several genes. Studies have already led to the identification of a number of susceptibility genes: NOD2, DLG5, OCTN1 (also called SLC22A4), OCTN2 (SLC22A5), NOD1, IL23R, PTGER4, ATG16L1 and IRGM. The NOD2 gene is currently the most replicated and understood.^[1]

With respect to age of CD onset and more specifically to childhood or early-onset Crohn’s disease, the following genes/loci have been implicated: TNFRSF6B, CXCL9, IL23R, NOD2, ATG16L1 rs2241880, CNR1, IL-10, and MDR1 (also called ABCB1).^[1]

In terms of genes related to CD location, studies have suggested that upper GI Crohn’s disease has been related to NOD2 and MIF variants. Ileal CD has been related to the IL-10, CRP, NOD2, ZNF365 and STAT3 genes. Genes/loci associated with ileocolonic CD are 3p21, ATG16L1 and TCF-4 (TCF7L2).^[1]

Variations in a number of genes have also been found to be associated with other aspects of CD, such as disease behavior, risk for cancer, and presence of extraintestinal manifestations.^[1] To view a free, full-text journal article published in 2012 about the role of genetics in CD, click here. To view only a table from this article listing the genes that appear to be associated with Crohn's disease, click here.

Because the information provided here is complex, individuals seeking to better understand this information may benefit from meeting with a genetics professional or other qualified health care provider.

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by the American College of Medical Genetics and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference.