IL23R

The IL23R gene provides instructions for making a protein called the interleukin 23 receptor. This receptor is present on the surface of several types of immune system cells including T cells, natural killer (NK) cells, monocytes, and dendritic cells. These cells identify foreign substances and defend the body against infection and disease. The interleukin 23 receptor spans the cell membrane, so that one end of the protein projects from the outer surface of the cell and the other end remains inside the cell.

The interleukin 23 receptor interacts with a protein called interleukin 23, fitting together like a lock and its key. Interleukin 23 is a cytokine, which is a type of protein that regulates the activity of immune system cells. When interleukin 23 binds to its receptor, it triggers certain chemical signals inside the cell. These signals promote inflammation and help coordinate the immune system's response to foreign invaders such as bacteria and viruses.

Crohn disease - associated with the IL23R gene

Several variations in or near the IL23R gene have been found to influence the risk of developing Crohn disease. This association has been found primarily in Caucasian (white) populations. One of these variations appears to reduce the likelihood of developing Crohn disease. This genetic change alters a single protein building block (amino acid) in the interleukin 23 receptor, replacing the amino acid arginine with the amino acid glutamine at protein position 381 (written as Arg381Glu). Although it is unclear how this change protects against Crohn disease, researchers believe that the receptor's role in triggering inflammation in the intestinal walls may underlie its connection with this disorder.

other disorders - associated with the IL23R gene

At least two variations in the IL23R gene have been associated with a skin disorder called psoriasis. People with this chronic inflammatory condition have patches of red, irritated skin that are often covered by flaky white scales. Psoriasis likely results from a malfunction of the immune system in which the body's immune response turns against itself, attacking healthy skin cells by mistake.

Each of the known IL23R variations changes a single amino acid in the interleukin 23 receptor. One of these variations, Arg381Gln, appears to reduce the risk of developing psoriasis. This variation has also been shown to protect against Crohn disease, another disorder associated with chronic inflammation. Researchers suggest that changes in the IL23R gene may contribute to general problems with regulation of the immune system, which may help explain why these variations are related to several different disorders characterized by immune system dysfunction.