What you carry at this position in your DNA and what research says about it.
Autoimmune Disease Risk: 8/10 evidence, 20 publications.
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Sample genotype (not yours): C/C
Lower Risk of Autoimmune Diseases
Carrying two copies of the C allele is associated with a lower risk of developing autoimmune conditions like rheumatoid arthritis and type 1 diabetes. However, there is a slightly higher risk of developing skin cancer.
What this genotype means: Lower risk of rheumatoid arthritis; Lower risk of type 1 diabetes; Slightly higher risk of skin cancer.
Sample genotype (not yours): C/T
Increased Risk of Autoimmune Diseases
Carrying one copy of the T allele is associated with an elevated risk of developing autoimmune conditions such as rheumatoid arthritis and type 1 diabetes. This genotype also offers a slightly lower risk of skin cancer.
What this genotype means: Increased risk of rheumatoid arthritis; Increased risk of type 1 diabetes; Slightly lower risk of skin cancer.
Sample genotype (not yours): T/T
Highest Risk of Autoimmune Diseases
Carrying two copies of the T allele is associated with the highest risk of developing autoimmune conditions like rheumatoid arthritis and type 1 diabetes. It also provides the lowest risk of skin cancer.
What this genotype means: Highest risk of rheumatoid arthritis; Highest risk of type 1 diabetes; Lowest risk of skin cancer.
Gene function and biological role
Gene Function: The IL2RA gene encodes the alpha chain of the interleukin-2 receptor, also known as CD25, which is a critical regulator of the human immune system [1]. This receptor is highly expressed on regulatory T-cells, which are responsible for maintaining immune tolerance and preventing the body from attacking its own tissues [1]. Proper signaling through this receptor helps control the balance between active immune responses and the suppression of self-reactive immune cells [2]. Variations in this gene can alter the expression or function of CD25, leading to a breakdown in immune homeostasis [3]. Consequently, IL2RA is a well-established susceptibility locus for a wide spectrum of autoimmune disorders [3].
Variant Impact: The variant rs706778 is an intronic single nucleotide polymorphism located in the first intron of the IL2RA gene. This genetic change is thought to reside within an enhancer region that influences the transcription and expression levels of the IL-2 receptor alpha chain [1]. By altering enhancer activity, the variant can affect how effectively regulatory T-cells respond to interleukin-2, thereby modulating immune tolerance [2]. The T allele of this variant is consistently associated with an increased risk of developing multiple autoimmune conditions, including rheumatoid arthritis and type 1 diabetes. Conversely, the C allele is associated with a slightly higher risk of skin cancer but is protective against autoimmune diseases [4].
Key Insight: This variant acts as an evolutionary trade-off, where alleles that protect against skin cancer simultaneously increase the risk of multiple autoimmune diseases.
Location: IL2RA. Chromosome 10 · 10p15.1 · 6.1 Mb
Estimated prevalence by population
Global 29.4%; European 34.6%; African 26.2%; East Asian 18.9%; South Asian 22.9%; Americas 21.0%; Ashkenazi 49.0%; Finnish 21.0%; Middle Eastern 40.9%; Amish 32.5%.
Estimated CC genotype frequency.
Global 49.0%; European 48.5%; African 50.0%; East Asian 49.1%; South Asian 49.9%; Americas 49.7%; Ashkenazi 42.0%; Finnish 49.7%; Middle Eastern 46.1%; Amish 49.0%.
Estimated CT genotype frequency.
Global 21.6%; European 17.0%; African 23.9%; East Asian 32.0%; South Asian 27.1%; Americas 29.3%; Ashkenazi 9.0%; Finnish 29.3%; Middle Eastern 13.0%; Amish 18.5%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Immunity & Inflammation
Autoimmune Diseases
Rheumatoid Arthritis. Evidence: 8/10. Source: PMID 20453842. Typical Risk.
Juvenile Arthritis. Evidence: 6/10. Source: PMID 26301688. Typical Risk.
Cardiovascular & Metabolic
Diabetes & Glycemic Traits
Type 1 Diabetes. Evidence: 8/10. Source: PMID 19106270. Typical Risk.
Endocrine & Reproductive
Hormone Levels & Endocrine Regulation
Hypothyroidism. Evidence: 6/10. Source: PMID 39024449. Typical Risk.
Cancer & Oncology
Skin Cancer
Skin Cancer. Evidence: 6/10. Source: PMID 39024449. Increased Risk.
Showing effects for C/T genotype
Rheumatoid Arthritis. Evidence: 8/10. Source: PMID 20453842. ~1.11x Risk.
Juvenile Arthritis. Evidence: 6/10. Source: PMID 26301688. ~1.17x Risk.
Type 1 Diabetes. Evidence: 8/10. Source: PMID 19106270. Increased Risk.
Hypothyroidism. Evidence: 6/10. Source: PMID 39024449. Increased Risk.
Skin Cancer. Evidence: 6/10. Source: PMID 39024449. Typical Risk.
Showing effects for T/T genotype
Rheumatoid Arthritis. Evidence: 8/10. Source: PMID 20453842. ~1.2x Risk.
Juvenile Arthritis. Evidence: 6/10. Source: PMID 26301688. ~1.3x Risk.
Type 1 Diabetes. Evidence: 8/10. Source: PMID 19106270. ~1.5x Risk.
Hypothyroidism. Evidence: 6/10. Source: PMID 39024449. Highest Risk.
Skin Cancer. Evidence: 6/10. Source: PMID 39024449. Lower Risk.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
This genotype is the most common globally and represents the baseline genetic profile for this variant. Having two copies of the C allele is linked to a reduced risk of rheumatoid arthritis compared to carriers of the T allele [1]. It also provides significant protection against the development of type 1 diabetes, particularly the acute-onset form [2]. This protective effect is thought to be mediated by maintaining optimal levels of the IL-2 receptor alpha chain on regulatory T-cells, which preserves immune tolerance [3]. While this genotype is highly favorable for avoiding autoimmune conditions, large-scale genetic studies have noted a minor association with an increased risk of skin cancer [4]. Overall, the substantial reduction in autoimmune risk makes this genotype highly beneficial for long-term immune health.
Lower risk of rheumatoid arthritis; Lower risk of type 1 diabetes; Slightly higher risk of skin cancer.
Sample genotype: CT (Heterozygous)
Having one copy of the T allele increases susceptibility to several autoimmune disorders due to altered immune regulation. This genotype is associated with an elevated risk of rheumatoid arthritis, as the T allele is a known risk-increasing variant [1]. It also increases the likelihood of developing type 1 diabetes by affecting the function of regulatory T-cells [2]. The genetic variation in the IL2RA gene is believed to impair the body's ability to suppress self-reactive immune cells, leading to inflammation [3]. Additionally, this genotype is linked to a higher risk of juvenile idiopathic arthritis and thyroid diseases like hypothyroidism [4]. On the positive side, carrying the T allele is associated with a slightly lower risk of skin cancer compared to the C/C genotype [5]. Maintaining a healthy lifestyle and being aware of early autoimmune symptoms can be helpful.
Increased risk of rheumatoid arthritis; Increased risk of type 1 diabetes; Slightly lower risk of skin cancer.
Sample genotype: TT (Homozygous)
This genotype carries the highest genetic risk for autoimmune diseases at this locus. Having two copies of the T allele is strongly associated with an increased risk of rheumatoid arthritis [1]. It also significantly elevates the risk of type 1 diabetes, particularly the acute-onset form, by altering the expression of the IL-2 receptor alpha chain [2]. This alteration impairs the regulatory T-cells' ability to maintain immune tolerance, allowing self-reactive immune cells to attack healthy tissues [3]. The T/T genotype is also linked to a higher risk of other pediatric and adult autoimmune diseases, including juvenile idiopathic arthritis and hypothyroidism [4]. Conversely, this genotype is associated with the lowest risk of skin cancer among all three genotypes [5]. Understanding this genetic predisposition can help in discussing immune health with a healthcare provider.
Highest risk of rheumatoid arthritis; Highest risk of type 1 diabetes; Lowest risk of skin cancer.
Variants with shared genetic architecture
rs61839660 · IL2RA Gene · Chr 10 · Autoimmune and Allergy Risk
rs2104286 · IL2RA Gene · Chr 10 · Autoimmune Disease Risk
rs706779 · IL2RA Gene · Chr 10 · Autoimmune Disease Risk
Toward further mapping of the association between the IL2RA locus and type 1 diabetes.
Diversity and scale: Genetic architecture of 2068 traits in the VA Million Veteran Program.
Genome-wide association study meta-analysis identifies seven new rheumatoid arthritis risk loci.
Meta-analysis of shared genetic architecture across ten pediatric autoimmune diseases.
Content updated August 2026.
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