What you carry at this position in your DNA and what research says about it.
Crohn Disease Risk: 8/10 evidence, 39 publications.
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Sample genotype (not yours): T/T
Typical Risk of Crohn Disease and Autoimmune Conditions
This genotype represents the baseline genetic profile, carrying two copies of the common T allele. It is associated with standard susceptibility to Crohn disease and other chronic inflammatory conditions.
What this genotype means: Typical susceptibility to inflammatory bowel diseases; Standard baseline risk for ankylosing spondylitis.
Sample genotype (not yours): G/G
Significantly Lowered Risk of Crohn Disease and Autoimmune Conditions
Carrying two copies of the protective G allele provides the strongest genetic defense against Crohn disease. It also substantially reduces the risk of several other chronic inflammatory disorders.
What this genotype means: Strongest genetic protection against Crohn disease; Significantly reduced risk of ankylosing spondylitis and psoriasis.
Sample genotype (not yours): T/G
Reduced Risk of Crohn Disease and Autoimmune Conditions
Carrying one copy of the protective G allele is associated with a lower risk of developing Crohn disease. It also offers moderate protection against other chronic inflammatory disorders.
What this genotype means: Lowered risk of developing Crohn disease; Moderate protection against joint and skin inflammation.
Gene function and biological role
Gene Function: The IL23R gene encodes a subunit of the receptor for interleukin-23, a key pro-inflammatory cytokine [1]. This receptor is essential for the survival and expansion of Th17 cells, which regulate mucosal immunity and inflammatory responses [2]. Dysregulation of this pathway is a major driver of chronic intestinal inflammation and joint-related autoimmune diseases [3]. Genetic variations in this gene can significantly alter susceptibility to various chronic inflammatory disorders [4].
Variant Impact: The rs7517847 variant is an intronic change located within the IL23R gene [2]. While it does not alter the protein sequence directly, it influences receptor expression and downstream immune signaling [3]. The minor G allele is widely recognized as a protective variant against chronic inflammatory conditions [1]. Conversely, the major T allele is associated with typical susceptibility to these autoimmune disorders [4].
Key Insight: The minor G allele of this variant acts as a natural genetic shield, significantly lowering the risk of developing Crohn disease and several other chronic inflammatory conditions.
Location: IL23R. Chromosome 1 · 1p31.3 · 67.2 Mb
Estimated prevalence by population
Global 40.6%; European 31.5%; African 64.2%; East Asian 31.6%; South Asian 49.4%; Americas 21.8%; Ashkenazi 44.9%; Finnish 32.1%; Middle Eastern 53.0%; Amish 33.4%.
Estimated TT genotype frequency.
Global 44.1%; European 49.2%; African 31.8%; East Asian 49.2%; South Asian 41.8%; Americas 49.8%; Ashkenazi 44.2%; Finnish 49.1%; Middle Eastern 39.6%; Amish 48.8%.
Estimated TG genotype frequency.
Global 15.3%; European 19.2%; African 3.9%; East Asian 19.2%; South Asian 8.8%; Americas 28.4%; Ashkenazi 10.9%; Finnish 18.7%; Middle Eastern 7.4%; Amish 17.8%.
Estimated GG genotype frequency.
Showing effects for T/T genotype
Immunity & Inflammation
Chronic Inflammatory Diseases
Crohn's Disease. Evidence: 8/10. Source: PMID 17435756. Typical Risk.
Ulcerative Colitis. Evidence: 6/10. Source: PMID 26974007. Typical Risk.
Autoimmune Diseases
Ankylosing Spondylitis. Evidence: 6/10. Source: PMID 26974007. Typical Risk.
Rheumatoid Arthritis. Evidence: 6/10. Source: PMID 33686288. Typical Risk.
Organ Systems
Skin & Hair Conditions
Psoriasis. Evidence: 6/10. Source: PMID 26974007. Typical Risk.
Showing effects for G/G genotype
Crohn's Disease. Evidence: 8/10. Source: PMID 17435756. ~35% Lower Risk.
Ulcerative Colitis. Evidence: 6/10. Source: PMID 26974007. Lowered Risk.
Ankylosing Spondylitis. Evidence: 6/10. Source: PMID 26974007. Lowered Risk.
Rheumatoid Arthritis. Evidence: 6/10. Source: PMID 33686288. Lowered Risk.
Psoriasis. Evidence: 6/10. Source: PMID 26974007. Lowered Risk.
Showing effects for T/G genotype
Crohn's Disease. Evidence: 8/10. Source: PMID 17435756. Reduced Risk.
Ulcerative Colitis. Evidence: 6/10. Source: PMID 26974007. Reduced Risk.
Ankylosing Spondylitis. Evidence: 6/10. Source: PMID 26974007. Reduced Risk.
Rheumatoid Arthritis. Evidence: 6/10. Source: PMID 33686288. Reduced Risk.
Psoriasis. Evidence: 6/10. Source: PMID 26974007. Reduced Risk.
What this genotype means for the people who carry it
Sample genotype: TT (Homozygous)
Carrying two copies of the common T allele at this locus represents the baseline genetic risk for several chronic inflammatory conditions. Large-scale genome-wide association studies have shown that individuals with the T/T genotype have a higher relative risk of developing Crohn disease compared to those carrying the protective G allele [1]. This variant is located within the IL23R gene, which is crucial for regulating the body's inflammatory response [2]. Without the protective G allele, the immune system maintains a standard level of susceptibility to autoimmune disorders like ankylosing spondylitis and psoriasis [2]. While this genotype does not guarantee the development of any disease, it lacks the protective benefit against mucosal inflammation seen in G allele carriers [3]. Maintaining a healthy lifestyle and monitoring for digestive or joint symptoms remains standard practice.
Typical susceptibility to inflammatory bowel diseases; Standard baseline risk for ankylosing spondylitis.
Sample genotype: GG (Homozygous)
Carrying two copies of the protective G allele provides the most robust genetic protection against Crohn disease, reducing the relative risk by approximately 35% compared to the common genotype [1]. This homozygous genotype is associated with a highly regulated immune response, preventing the hyper-activation of the interleukin-23 pathway that typically triggers chronic mucosal inflammation [2]. Beyond inflammatory bowel disease, the G/G genotype is consistently linked to a significantly decreased susceptibility to other autoimmune conditions, including ankylosing spondylitis, psoriasis, and ulcerative colitis [2]. Clinical cohorts have shown that individuals with this genetic profile are less likely to develop severe inflammatory symptoms or require aggressive immunosuppressive therapies [3]. This variant serves as a prime example of a natural genetic shield against chronic inflammatory disorders.
Strongest genetic protection against Crohn disease; Significantly reduced risk of ankylosing spondylitis and psoriasis.
Sample genotype: TG (Heterozygous)
Having one copy of the protective G allele significantly lowers the likelihood of developing Crohn disease compared to the typical T/T genotype [1]. This protective effect is thought to stem from altered signaling within the interleukin-23 pathway, which reduces the overactive immune responses that drive chronic gut inflammation [2]. Research indicates that this single protective allele also extends moderate defense against other autoimmune conditions, such as ankylosing spondylitis and psoriasis [2]. Clinical studies have observed that carriers of the G allele tend to experience milder inflammatory phenotypes and fewer severe symptoms [3]. This genetic marker highlights how subtle variations in immune receptors can naturally buffer the body against chronic inflammation.
Lowered risk of developing Crohn disease; Moderate protection against joint and skin inflammation.
Variants with shared genetic architecture
rs11209026 · IL23R Gene · Chr 1 · Autoimmune Disease Risk
rs11465804 · IL23R Gene · Chr 1 · Inflammatory Disease Risk
rs1004819 · IL23R Gene · Chr 1 · Crohn's Disease Risk
Content updated August 2026.
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