A genome-wide assessment of genetic variation in individuals with Crohn disease has identified seven genes or regions that are associated with elevated risk of the disease, according to a study to be published online this week in Nature Genetics.
Three of the genes were previously known, but four are newly associated with the disease.
Crohn disease is one of the most common forms of inflammatory bowel disease, affecting 100-150 per 100,000 individuals of European ancestry. John Rioux and colleagues assessed more than 300,000 genetic variants in individuals with Crohn disease, as well as controls, and identified three previously reported risk factors (CARD15, IL23R, and ATG16L1), and four new ones (PHOX2B, NCF4, FAM92B, and a region on chromosome 10).
In combination with other studies, these ‘genome-wide association studies’ promise to flesh out the entire catalogue of genetic variants that predispose to Crohn disease, as well as provide new insight into the causes of the disease. In this case, the authors show that ATG16L1 might have a role in the degradation and processing of bacteria by the body’s inflammatory response– a process known as autophagy. This is consistent with other evidence that an inappropriate response to bacteria in the gut is important in the initiation of Crohn disease.