IRGM

The IRGM gene provides instructions for making a protein that plays an important role in the immune system. This protein is involved in a process called autophagy, which cells use to surround and destroy foreign invaders such as bacteria and viruses. Specifically, the IRGM protein helps trigger autophagy in cells infected with certain kinds of bacteria (mycobacteria), including the type of bacteria that causes tuberculosis. In addition to protecting cells from infection, autophagy is used to recycle worn-out cell parts and break down certain proteins when they are no longer needed. This process also plays an important role in controlled cell death (apoptosis).

Crohn disease - increased risk from variations of the IRGM gene

Several variations in or near the IRGM gene have been associated with an increased risk of developing Crohn disease. This increased risk has been found primarily in Caucasian (white) populations. IRGM variations change single DNA building blocks (nucleotides) in regions of DNA that may regulate when and how the IRGM protein is produced. It is unclear how these changes influence a person's chance of developing Crohn disease. Researchers suspect that changes involving the IRGM protein may disrupt the autophagy process, preventing the immune system from destroying harmful bacteria effectively. An abnormal immune response to bacteria in the intestinal walls may lead to chronic inflammation and the digestive problems characteristic of Crohn disease.