What you carry at this position in your DNA and what research says about it.
Autoimmune Disease Risk: 6/10 evidence, 29 publications.
You're viewing every possible genotype for this variant.
None of these is your result. Use the genotype toggle to compare them, then sign up and upload your DNA to see which one is yours.
Sample genotype (not yours): A/A
Higher Crohn's and Thyroid Risk, Lower Multiple Sclerosis Risk
Carriage of two A alleles is associated with an increased susceptibility to inflammatory bowel disease and autoimmune thyroid conditions. Conversely, this same genetic profile is linked to a reduced risk of developing multiple sclerosis.
What this genotype means: Higher susceptibility to Crohn's disease and ulcerative colitis; Increased risk of autoimmune thyroid disorders; Lower risk of multiple sclerosis.
Sample genotype (not yours): A/G
Increased Risk of Autoimmune Conditions
Carrying one A allele and one G allele is associated with an intermediate risk profile for several autoimmune disorders. This includes a moderately increased susceptibility to both inflammatory bowel disease and multiple sclerosis.
What this genotype means: Moderate risk of inflammatory bowel disease; Moderate risk of multiple sclerosis; Intermediate risk of thyroid autoimmunity.
Sample genotype (not yours): G/G
Higher Multiple Sclerosis Risk, Lower Crohn's and Thyroid Risk
Carriage of two G alleles is linked to an increased risk of multiple sclerosis. However, this genotype offers protection against inflammatory bowel disease, autoimmune thyroid disorders, and gastric cancer.
What this genotype means: Higher risk of multiple sclerosis; Lower risk of Crohn's disease and ulcerative colitis; Reduced risk of autoimmune thyroid conditions.
Gene function and biological role
Gene Function: STAT3 encodes a transcription factor that plays a key role in cell growth, survival, and immune response. It is activated in response to various cytokines and growth factors, mediating the expression of genes involved in inflammation. Dysregulation of this pathway is heavily implicated in autoimmune disorders and cancers. The protein is particularly crucial for the differentiation of T-helper 17 cells, which are key drivers of chronic inflammation.
Variant Impact: Located within an intron of the STAT3 gene, rs744166 is thought to influence gene expression levels or alter how the STAT3 protein responds to inflammatory cytokines. This genetic change has been widely studied for its contrasting roles in different autoimmune conditions. It represents a classic genetic trade-off, where an allele that increases susceptibility to one disease protects against another.
Key Insight: This variant presents an evolutionary trade-off, where the same genetic letter that increases the risk of inflammatory bowel disease actually lowers the risk of multiple sclerosis.
Location: STAT3. Chromosome 17 · 17q21.2 · 42.4 Mb
Estimated prevalence by population
Global 29.0%; European 34.6%; African 10.4%; East Asian 34.1%; South Asian 26.3%; Americas 47.7%; Ashkenazi 35.0%; Finnish 33.4%; Middle Eastern 37.5%; Amish 38.9%.
Estimated AA genotype frequency.
Global 46.6%; European 48.4%; African 43.6%; East Asian 48.6%; South Asian 50.0%; Americas 42.7%; Ashkenazi 48.3%; Finnish 48.8%; Middle Eastern 47.5%; Amish 46.9%.
Estimated AG genotype frequency.
Global 24.4%; European 17.0%; African 46.0%; East Asian 17.3%; South Asian 23.8%; Americas 9.6%; Ashkenazi 16.7%; Finnish 17.8%; Middle Eastern 15.0%; Amish 14.2%.
Estimated GG genotype frequency.
Showing effects for A/A genotype
Immunity & Inflammation
Chronic Inflammatory Diseases
Crohn's Disease. Evidence: 6/10. Source: PMID 26192919. Increased Risk.
Autoimmune Diseases
Multiple Sclerosis. Evidence: 5/10. Source: PMID 20159113. Typical Risk.
Thyroid Autoimmunity. Evidence: 3/10. Source: PMID 26204395. Increased Risk.
Cancer & Oncology
Gastrointestinal Cancers
Gastric Cancer. Evidence: 3/10. Source: PMID 24864251. Increased Risk.
Showing effects for A/G genotype
Multiple Sclerosis. Evidence: 5/10. Source: PMID 20159113. Increased Risk.
Showing effects for G/G genotype
Crohn's Disease. Evidence: 6/10. Source: PMID 26192919. Typical Risk.
Thyroid Autoimmunity. Evidence: 3/10. Source: PMID 26204395. Typical Risk.
Gastric Cancer. Evidence: 3/10. Source: PMID 24864251. Typical Risk.
What this genotype means for the people who carry it
Sample genotype: AA (Homozygous)
Genetic studies indicate that the A allele significantly elevates the risk of Crohn's disease and ulcerative colitis. This variant is also associated with a higher likelihood of autoimmune thyroid diseases, such as Graves' disease and Hashimoto's thyroiditis. Research suggests that the A allele may lead to increased basal activation of the STAT3 protein, promoting inflammatory pathways in the gut and thyroid. However, this heightened immune activity appears to be protective against multiple sclerosis, with A/A individuals showing a lower incidence of the condition. Additionally, some studies have linked the A allele to an increased susceptibility to gastric cancer. This dual nature highlights how genetic variants can have complex, tissue-specific effects on the immune system. Understanding these patterns helps researchers map the shared pathways of chronic inflammatory disorders.
Higher susceptibility to Crohn's disease and ulcerative colitis; Increased risk of autoimmune thyroid disorders; Lower risk of multiple sclerosis.
Sample genotype: AG (Heterozygous)
Having a heterozygous genotype means carrying both the A and G alleles, which are associated with opposing autoimmune risks. The presence of the A allele increases the risk of developing inflammatory bowel disease, including Crohn's disease. Simultaneously, the G allele is linked to a higher susceptibility to multiple sclerosis. This combination can lead to a moderate increase in overall autoimmune susceptibility, as both inflammatory pathways are partially active. Studies also show that this genotype carries an intermediate risk for autoimmune thyroid diseases compared to the homozygous states. Because both risk alleles are present, the immune system may exhibit balanced but elevated inflammatory signaling. This intermediate profile underscores the complexity of predicting autoimmune risk from a single genetic locus.
Moderate risk of inflammatory bowel disease; Moderate risk of multiple sclerosis; Intermediate risk of thyroid autoimmunity.
Sample genotype: GG (Homozygous)
Large-scale association studies have identified the G allele as a risk factor for multiple sclerosis, with G/G individuals having the highest susceptibility. This genetic profile is thought to alter immune cell responses in a way that favors neuroinflammation. On the positive side, the G allele is highly protective against inflammatory bowel disease, significantly reducing the risk of Crohn's disease and ulcerative colitis. It also lowers the likelihood of developing autoimmune thyroid diseases. Furthermore, research in Asian populations suggests that the G allele is associated with a decreased risk of gastric cancer. These findings demonstrate that a genetic variant can be disadvantageous for one organ system while being highly beneficial for another. This trade-off is a key reason why both alleles have persisted in the human population over generations.
Higher risk of multiple sclerosis; Lower risk of Crohn's disease and ulcerative colitis; Reduced risk of autoimmune thyroid conditions.
Variants with shared genetic architecture
rs1053004 · STAT3 Gene · Chr 17 · Cancer and Treatment Response
rs1053005 · STAT3 Gene · Chr 17 · Immune and Metabolic Balance
rs2293152 · STAT3 Gene · Chr 17 · Autoimmune Disease Risk
Content updated August 2026.
ReadYourDNA provides educational interpretation of DNA data you already have. It is not diagnostic, not a substitute for professional medical advice, diagnosis, or treatment, and is not intended to diagnose, treat, cure, or prevent any disease. Talk to a clinician before acting on any result.
Raw DNA Data Reports for 23andMe & AncestryDNA · About ReadYourDNA · FAQ · Methodology & Science · Pricing · Support and complaints · Legal & Contact · Health Traits · Pharmacogenomics · Carrier Status · Variant Explorer · The Human Karyotype · Privacy Policy · Terms of Service · Accessibility · Consumer Health Data Privacy · Your Privacy Choices · Editorial Standards · Your Data, Checkable · Sample Report · ReadYourDNA and Promethease compared · What is inside a 23andMe raw data file · What is inside an AncestryDNA raw data file · What a chatbot can and cannot do with your raw DNA file · Where a raw DNA file can still be uploaded in 2026
Written, maintained and operated by Martin Pechhacker, sole proprietor, Vienna, Austria. Trade register GISA 40064420. support@readyourdna.com