What you carry at this position in your DNA and what research says about it.
Type 1 Diabetes Risk: 8/10 evidence, 20 publications.
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Sample genotype (not yours): C/C
Higher Risk of Type 1 Diabetes and Asthma
Two copies of the C allele are associated with a significantly higher risk of developing type 1 diabetes and allergic conditions like asthma. However, this genotype is also linked to higher levels of HDL cholesterol.
What this genotype means: Increased risk of type 1 diabetes; Higher susceptibility to asthma and eczema; Higher HDL cholesterol levels.
Sample genotype (not yours): C/T
Moderately Increased Risk of Type 1 Diabetes and Asthma
One copy of the C allele is associated with a moderately increased risk of developing type 1 diabetes and allergic conditions. It also correlates with slightly higher HDL cholesterol levels.
What this genotype means: Moderately increased risk of type 1 diabetes; Slightly higher susceptibility to asthma; Slightly higher HDL cholesterol levels.
Sample genotype (not yours): T/T
Typical Risk of Type 1 Diabetes and Asthma
Two copies of the T allele are associated with a normal, baseline risk of developing type 1 diabetes and allergic conditions. It is also linked to typical levels of HDL cholesterol.
What this genotype means: Typical baseline risk of type 1 diabetes; Typical susceptibility to asthma; Typical HDL cholesterol levels.
Gene function and biological role
Gene Function: The ERBB3 gene encodes a member of the epidermal growth factor receptor family of receptor tyrosine kinases. This protein plays an essential role in cell proliferation, differentiation, and survival [1]. In the immune system, ERBB3 is expressed on the surface of antigen-presenting cells, such as dendritic cells and monocytes [1]. Genetic variations in this gene can alter immune cell activation and have been strongly linked to susceptibility to autoimmune disorders [2].
Variant Impact: The rs11171739 variant is an intergenic single nucleotide polymorphism located near the ERBB3 and RPS26 genes on chromosome 12. This genetic change acts as an expression quantitative trait locus, meaning it influences how nearby genes are read and expressed [3]. Specifically, the variant alters the expression levels of ERBB3 and RPS26 in immune cells [3]. These expression changes modulate the function of antigen-presenting cells, thereby affecting the body's inflammatory and autoimmune responses [1].
Key Insight: This variant represents a genetic link between autoimmune diseases like type 1 diabetes and allergic conditions like asthma, showing how shared immune pathways underlie both types of disorders.
Location: ERBB3. Chromosome 12 · 12q13.2 · 56.1 Mb
Estimated prevalence by population
Global 27.9%; European 17.1%; African 60.2%; East Asian 5.1%; South Asian 8.0%; Americas 12.5%; Ashkenazi 21.4%; Finnish 16.8%; Middle Eastern 11.3%; Amish 33.8%.
Estimated CC genotype frequency.
Global 43.7%; European 48.5%; African 34.8%; East Asian 35.0%; South Asian 40.6%; Americas 45.7%; Ashkenazi 49.7%; Finnish 48.4%; Middle Eastern 44.6%; Amish 48.7%.
Estimated CT genotype frequency.
Global 28.3%; European 34.4%; African 5.0%; East Asian 59.9%; South Asian 51.4%; Americas 41.8%; Ashkenazi 28.9%; Finnish 34.9%; Middle Eastern 44.1%; Amish 17.5%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Cardiovascular & Metabolic
Diabetes & Glycemic Traits
Type 1 Diabetes. Evidence: 8/10. Source: PMID 17554300. ~1.75x Risk.
Lipids & Cholesterol
HDL Cholesterol. Evidence: 6/10. Source: PMID 34887591. Higher Levels.
Immunity & Inflammation
Allergy & Hypersensitivity
Asthma and Allergies. Evidence: 6/10. Source: PMID 29785011. Increased Risk.
Neurology & Mental Health
Neurodevelopmental Traits
Cerebral Cortex Area. Evidence: 5/10. Source: PMID 32193296. Larger Area.
Showing effects for C/T genotype
Type 1 Diabetes. Evidence: 8/10. Source: PMID 17554300. ~1.34x Risk.
HDL Cholesterol. Evidence: 6/10. Source: PMID 34887591. Slightly Higher.
Asthma and Allergies. Evidence: 6/10. Source: PMID 29785011. Slightly Increased.
Cerebral Cortex Area. Evidence: 5/10. Source: PMID 32193296. Slightly Larger.
Showing effects for T/T genotype
Type 1 Diabetes. Evidence: 8/10. Source: PMID 17554300. Typical Risk.
HDL Cholesterol. Evidence: 6/10. Source: PMID 34887591. Typical Levels.
Asthma and Allergies. Evidence: 6/10. Source: PMID 29785011. Typical Risk.
Cerebral Cortex Area. Evidence: 5/10. Source: PMID 32193296. Typical Area.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Carrying two copies of the C allele is associated with an estimated 1.75-fold increase in the risk of developing type 1 diabetes [1]. This genetic variant alters the expression of the ERBB3 gene, which is crucial for the proper function of antigen-presenting immune cells [2]. When these immune cells function abnormally, it can trigger an autoimmune attack against insulin-producing beta cells in the pancreas [2]. In addition to diabetes, this genotype is linked to an increased susceptibility to allergic diseases, including asthma and eczema [3]. Interestingly, the same genetic pathway is associated with some beneficial traits, such as higher levels of HDL, or good, cholesterol [4]. It is also linked to differences in brain structure, including a larger cerebral cortex area [5].
Increased risk of type 1 diabetes; Higher susceptibility to asthma and eczema; Higher HDL cholesterol levels.
Sample genotype: CT (Heterozygous)
Carrying one copy of the C allele is associated with an estimated 1.34-fold increase in the risk of developing type 1 diabetes [1]. This heterozygous genotype leads to intermediate expression levels of the ERBB3 gene in immune cells, moderately affecting antigen-presenting cell function [2]. Consequently, individuals with this genotype have a moderate predisposition to autoimmune responses [2]. There is also a slightly elevated risk of developing allergic conditions such as asthma and atopic eczema [3]. On the positive side, this genotype is associated with slightly higher levels of HDL cholesterol, which supports cardiovascular health [4]. Additionally, studies have linked this variant to minor differences in brain morphology, such as cerebral cortex area [5].
Moderately increased risk of type 1 diabetes; Slightly higher susceptibility to asthma; Slightly higher HDL cholesterol levels.
Sample genotype: TT (Homozygous)
Carrying two copies of the T allele represents the baseline genetic profile for type 1 diabetes risk, with no elevated susceptibility [1]. This genotype is associated with typical expression of the ERBB3 gene, maintaining normal immune cell regulation and antigen-presenting function [2]. As a result, there is no genetically driven increase in autoimmune activity against pancreatic beta cells [2]. Individuals with this genotype also have a typical, baseline risk for allergic diseases such as asthma and eczema [3]. While this genotype avoids the elevated risks of autoimmune and allergic conditions, it is associated with typical, rather than elevated, levels of HDL cholesterol [4]. It is also linked to standard brain morphology measurements, including typical cerebral cortex area [5].
Typical baseline risk of type 1 diabetes; Typical susceptibility to asthma; Typical HDL cholesterol levels.
Variants with shared genetic architecture
rs2292239 · ERBB3 Gene · Chr 12 · Type 1 Diabetes Risk
rs9272346 · HLA-DQA1 Gene · Chr 6 · Type 1 Diabetes Risk
rs947474 · LINC02656 Gene · Chr 10 · Rheumatoid Arthritis Risk
Genome-wide association study of 14,000 cases of seven common diseases and 3,000 shared controls.
The power of genetic diversity in genome-wide association studies of lipids.
The genetic architecture of the human cerebral cortex.
Content updated August 2026.
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