What you carry at this position in your DNA and what research says about it.
Crohn's Disease Risk: 10/10 evidence, 42 publications.
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Sample genotype (not yours): G/G
Typical Crohn's Disease Risk
Carrying two copies of the common G allele represents the baseline genetic risk for Crohn's disease. The immune system's ability to recognize and respond to gut bacteria remains typical.
What this genotype means: Typical baseline risk of inflammatory bowel disease; Normal NOD2 receptor function and bacterial sensing.
Sample genotype (not yours): C/C
~35x Higher Crohn's Disease Risk
Carrying two copies of the C allele is associated with a highly elevated risk of developing Crohn's disease. This genotype significantly impairs the body's ability to recognize gut bacteria, leading to chronic inflammation.
What this genotype means: Significantly increased risk of developing Crohn's disease; Higher likelihood of early-onset and severe disease course.
Sample genotype (not yours): G/C
~3x Higher Crohn's Disease Risk
Carrying one copy of the C allele is associated with a moderately increased risk of developing Crohn's disease. This variant alters the immune system's ability to monitor gut bacteria.
What this genotype means: Moderately increased risk of Crohn's disease; Slightly higher susceptibility to other inflammatory conditions.
Gene function and biological role
Gene Function: The NOD2 gene encodes a cytosolic pattern recognition receptor that plays a critical role in the innate immune system. It is responsible for detecting bacterial peptidoglycans, specifically muramyl dipeptide, within cells [1]. Upon sensing these bacterial components, the protein activates inflammatory signaling pathways to clear infections and maintain gut homeostasis [2]. Genetic variations in this gene can impair bacterial sensing, leading to persistent inflammation and an altered gut microbiome [3]. Consequently, it is the most well-established genetic susceptibility locus for Crohn's disease [4].
Variant Impact: The rs2066845 variant is a missense mutation in exon 8 of the NOD2 gene, resulting in a change from glycine to arginine at position 881 [1]. This amino acid substitution occurs within the leucine-rich repeat domain, which is responsible for detecting bacterial cell wall components [1]. The structural change impairs the receptor's ability to recognize bacteria, leading to a compromised innate immune response and chronic mucosal inflammation [3]. It is one of the three major NOD2 susceptibility variants linked to Crohn's disease in European-ancestry populations [4].
Key Insight: Carrying two copies of this variant can increase the risk of Crohn's disease by up to 35-fold, making it one of the strongest known genetic risk factors for the condition.
Location: NOD2. Chromosome 16 · 16q12.1 · 50.7 Mb
Estimated prevalence by population
Global 98.0%; European 97.1%; African 99.5%; East Asian 100.0%; South Asian 98.8%; Americas 97.3%; Ashkenazi 91.5%; Finnish 99.5%; Middle Eastern 95.3%; Amish 99.6%.
Estimated GG genotype frequency.
Global 2.0%; European 2.9%; African 0.5%; East Asian 0.0%; South Asian 1.2%; Americas 2.7%; Ashkenazi 8.3%; Finnish 0.5%; Middle Eastern 4.6%; Amish 0.4%.
Estimated GC genotype frequency.
Global < 0.1%; European < 0.1%; African < 0.1%; East Asian 0.0%; South Asian < 0.1%; Americas < 0.1%; Ashkenazi 0.2%; Finnish < 0.1%; Middle Eastern 0.1%; Amish < 0.1%.
Estimated CC genotype frequency.
Showing effects for G/G genotype
Immunity & Inflammation
Chronic Inflammatory Diseases
Crohn's Disease. Evidence: 10/10. Source: PMID 19570052. Typical Risk.
Ulcerative Colitis. Evidence: 8/10. Source: PMID 26974007. Typical Risk.
Autoimmune Diseases
Ankylosing Spondylitis. Evidence: 8/10. Source: PMID 26974007. Typical Risk.
Organ Systems
Skin & Hair Conditions
Psoriasis. Evidence: 8/10. Source: PMID 26974007. Typical Risk.
Showing effects for C/C genotype
Crohn's Disease. Evidence: 10/10. Source: PMID 19570052. ~35x Higher Risk.
Ulcerative Colitis. Evidence: 8/10. Source: PMID 26974007. Increased Risk.
Ankylosing Spondylitis. Evidence: 8/10. Source: PMID 26974007. Increased Risk.
Psoriasis. Evidence: 8/10. Source: PMID 26974007. Increased Risk.
Showing effects for G/C genotype
Crohn's Disease. Evidence: 10/10. Source: PMID 19570052. ~3x Higher Risk.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Having two copies of the G allele means you do not carry the rs2066845 risk variant. This genotype is highly common, occurring in over 98% of the global population. Studies show that individuals with this baseline genotype have a typical, non-elevated risk of developing Crohn's disease and other chronic inflammatory conditions [1]. The NOD2 protein functions normally, allowing the immune system to properly detect bacterial components in the gut and maintain a healthy mucosal barrier [2]. Because you lack this specific risk allele, you do not have the elevated susceptibility to ileal disease or early surgical intervention associated with the variant [3]. However, overall risk is still influenced by other genetic markers and environmental factors like diet and smoking [4].
Typical baseline risk of inflammatory bowel disease; Normal NOD2 receptor function and bacterial sensing.
Sample genotype: CC (Homozygous)
Carrying two copies of the C allele is associated with a highly elevated risk of Crohn's disease, estimated to be 20- to 40-fold higher than the general population [1]. This genotype severely compromises the NOD2 receptor's ability to detect bacterial molecules in the intestinal tract [2]. The resulting lack of bacterial clearance triggers a compensatory, hyper-inflammatory response from the adaptive immune system, causing chronic tissue damage [3]. Individuals with this genotype are more likely to experience early-onset disease, involvement of the ileum, and a higher likelihood of requiring surgical intervention [4]. It is also associated with an increased risk of other inflammatory conditions, including ankylosing spondylitis and ulcerative colitis [5]. Despite the high relative risk, environmental triggers and other genetic factors still determine whether the disease ultimately manifests [6].
Significantly increased risk of developing Crohn's disease; Higher likelihood of early-onset and severe disease course.
Sample genotype: GC (Heterozygous)
Carrying one copy of the C allele is linked to a roughly threefold increase in the risk of developing Crohn's disease [1]. This genetic change alters the leucine-rich repeat domain of the NOD2 receptor, making it less effective at sensing bacterial cell wall components [2]. As a result, the body may struggle to regulate its immune response to normal gut microbes, leading to localized inflammation [3]. Heterozygous carriers are also slightly more susceptible to other inflammatory conditions, such as psoriatic arthritis or ankylosing spondylitis [4]. While this variant increases susceptibility, many people with this genotype never develop Crohn's disease, as environmental factors like smoking and diet play a major role [5].
Moderately increased risk of Crohn's disease; Slightly higher susceptibility to other inflammatory conditions.
Variants with shared genetic architecture
rs2076756 · NOD2 Gene · Chr 16 · Crohn's Disease Risk
rs2066847 · NOD2 Gene · Chr 16 · Crohn's Disease Risk
rs2066844 · NOD2 Gene · Chr 16 · Crohn's Disease Risk
Association of NOD2 leucine-rich repeat variants with susceptibility to Crohn's disease.
NOD2/CARD15 genotype and common gastrointestinal diseases in 43,600 individuals.
Influence of Crohn's disease risk alleles and smoking on disease location.
Content updated August 2026.
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