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IL23R gene

Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

IL23R gene

The IL23R gene encodes a receptor protein that regulates immune system inflammation, playing a significant role in the risk of various autoimmune and inflammatory conditions.

Normal Function

The IL23R gene provides instructions for making a protein called the interleukin 23 (IL-23) receptor. This protein is embedded in the outer membrane 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.

At the cell surface, the IL-23 receptor interacts with IL-23, a cytokine that regulates immune cell activity. When IL-23 binds to its receptor, it triggers chemical signals inside the cell that promote inflammation and coordinate the immune system's response to invaders like bacteria and viruses.

Health Conditions Related to Genetic Changes

Ankylosing spondylitis

Several variations (polymorphisms) in the IL23R gene influence the risk of ankylosing spondylitis, a form of chronic inflammatory arthritis that primarily affects the spine. One polymorphism, Arg381Gln (or R381Q), appears to reduce the risk of developing this disorder. Other variations may increase the risk. While the exact mechanism is not fully understood, these effects are likely related to the receptor's role in inflammation.

Crohn's disease

Variants in or near the IL23R gene influence the risk of developing Crohn's disease, particularly in people of northern European ancestry. The Arg381Gln variant, which protects against ankylosing spondylitis, also appears to reduce the risk of Crohn's disease. Researchers believe the receptor's role in triggering inflammation in the intestinal walls may underlie this connection.

Psoriatic arthritis

MedlinePlus Genetics provides information about Psoriatic arthritis.

Ulcerative colitis

MedlinePlus Genetics provides information about Ulcerative colitis.

Other disorders

Variants in the IL23R gene are associated with the risk of other immune-related conditions, including psoriasis. Psoriasis is a chronic inflammatory condition where the immune system mistakenly attacks healthy skin cells. The Arg381Gln variant appears to protect against psoriasis, while other variations may increase risk. These findings suggest that IL23R gene changes contribute to general immune system dysregulation.

Genomic Location

The IL23R gene is found on chromosome 1.

Frequently Asked Questions

Testing for IL23R variants is optional and usually performed as part of a broader inflammatory‑bowel‑disease gene panel. A positive risk allele may reinforce the need for early surveillance (e.g., colonoscopy) and may influence therapeutic choices, such as earlier consideration of IL‑23‑targeted biologics. However, a negative result does not guarantee protection, and management decisions remain based on clinical presentation and family history.
Ustekinumab and similar agents block the IL‑23 cytokine pathway, reducing downstream inflammation that drives Crohn’s disease, ulcerative colitis, psoriatic arthritis, and related conditions. Their efficacy is independent of a patient’s IL23R genotype; clinical trials have shown benefit across genotypes. Patients with high‑risk IL23R variants may be good candidates for these drugs, especially if conventional therapies fail, but the decision rests on disease severity, prior treatment response, and safety considerations.
dopting an anti‑inflammatory lifestyle can complement medical therapy. Recommendations include a Mediterranean‑style diet rich in omega‑3 fatty acids, fiber, fruits, and vegetables; limiting processed foods, red meat, and added sugars; maintaining a healthy weight; regular moderate exercise; and avoiding smoking, which markedly increases IBD risk. Probiotic‑rich foods or supplements may help modulate gut microbiota, though evidence is still emerging. These measures do not replace medication but can reduce flare frequency and overall disease burden.
No. The Arg381Gln (R381Q) variant lowers the relative risk but does not eliminate it. Disease risk is multifactorial, involving many other genes, environmental triggers, and gut microbiome composition. Even carriers of the protective allele can develop Crohn’s disease or ankylosing spondylitis, especially if they have additional risk factors.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.