What you carry at this position in your DNA and what research says about it.
Autoimmune Disease Risk: 8/10 evidence, 22 publications.
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Sample genotype (not yours): C/C
Typical Autoimmune Risk
Carrying two copies of the common C allele is associated with typical, baseline risk for autoimmune conditions like celiac disease and lupus. It is also associated with a very slight increase in baseline diastolic blood pressure.
What this genotype means: Typical baseline risk for celiac disease; Typical baseline risk for lupus.
Sample genotype (not yours): C/T
Increased Risk of Autoimmune Conditions
Carrying one copy of the T allele is associated with a significantly higher risk of developing celiac disease and lupus. It also slightly lowers the baseline diastolic blood pressure.
What this genotype means: Increased risk of celiac disease; Increased risk of lupus.
Sample genotype (not yours): T/T
Significantly Increased Risk of Autoimmune Conditions
Carrying two copies of the T allele is linked to a highly elevated risk of celiac disease, lupus, and other autoimmune disorders. It is also associated with slightly lower diastolic blood pressure.
What this genotype means: Highly elevated risk of celiac disease; Highly elevated risk of lupus.
Gene function and biological role
Gene Function: The HLA-DQA1 gene belongs to a family of genes called the human leukocyte antigen complex, which plays a central role in the human immune system. This gene provides instructions for making a protein that forms a functional antigen-presenting receptor on the surface of immune cells. This receptor helps the immune system distinguish the body's own proteins from foreign proteins made by invaders like viruses and bacteria. Variations within this gene can disrupt this recognition process, leading the immune system to mistakenly attack healthy tissues [1]. Consequently, HLA-DQA1 is one of the most heavily studied genetic regions for susceptibility to various autoimmune disorders [1] [2].
Variant Impact: The rs2187668 variant is an intronic change located within the HLA-DQA1 gene. This specific genetic variation serves as a highly reliable tag or proxy for the HLA-DRB1*0301 allele and the DQ2.5 haplotype [1]. These immune profiles are critical because they alter how antigens are presented to T cells, directly influencing immune tolerance [1] [3]. Carrying the T variant allele significantly increases the likelihood of the immune system losing tolerance to self-proteins or common dietary proteins like gluten [1]. As a result, this variant is strongly associated with a broad spectrum of autoimmune conditions [1] [2].
Key Insight: This single genetic marker acts as a powerful proxy for the DQ2.5 haplotype, which is the primary genetic driver behind celiac disease susceptibility.
Location: HLA-DQA1. Chromosome 6 · 6p21.32 · 32.6 Mb
Estimated prevalence by population
Global 99.3%; European 99.0%; African 99.8%; East Asian 99.0%; South Asian 99.2%; Americas 99.5%; Ashkenazi 99.5%; Finnish 99.7%; Middle Eastern 96.5%; Amish 100.0%.
Estimated CC genotype frequency.
Global 0.7%; European 1.0%; African 0.2%; East Asian 1.0%; South Asian 0.8%; Americas 0.5%; Ashkenazi 0.5%; Finnish 0.3%; Middle Eastern 3.5%; Amish 0.0%.
Estimated CT genotype frequency.
Global < 0.1%; European < 0.1%; African < 0.1%; East Asian < 0.1%; South Asian < 0.1%; Americas < 0.1%; Ashkenazi < 0.1%; Finnish < 0.1%; Middle Eastern < 0.1%; Amish 0.0%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Immunity & Inflammation
Autoimmune Diseases
Celiac Disease. Evidence: 8/10. Source: PMID 20190752. Typical Risk.
Lupus. Evidence: 7/10. Source: PMID 26316170. Typical Risk.
Chronic Inflammatory Diseases
Sarcoidosis. Evidence: 4/10. Source: PMID 26651848. Typical Risk.
Organ Systems
Skin & Hair Conditions
Cutaneous Lupus. Evidence: 4/10. Source: PMID 25827949. Typical Risk.
Cardiovascular & Metabolic
Hypertension
Diastolic Blood Pressure. Evidence: 7/10. Source: PMID 27618452. +0.37 mmHg.
Showing effects for C/T genotype
Celiac Disease. Evidence: 8/10. Source: PMID 20190752. ~6.5x Increased Risk.
Lupus. Evidence: 7/10. Source: PMID 26316170. ~2.2x Increased Risk.
Sarcoidosis. Evidence: 4/10. Source: PMID 26651848. ~3.4x Increased Risk.
Cutaneous Lupus. Evidence: 4/10. Source: PMID 25827949. ~2.9x Increased Risk.
Diastolic Blood Pressure. Evidence: 7/10. Source: PMID 27618452. Typical.
Showing effects for T/T genotype
Celiac Disease. Evidence: 8/10. Source: PMID 20190752. Highly Elevated Risk.
Lupus. Evidence: 7/10. Source: PMID 26316170. Highly Elevated Risk.
Sarcoidosis. Evidence: 4/10. Source: PMID 26651848. Highly Elevated Risk.
Cutaneous Lupus. Evidence: 4/10. Source: PMID 25827949. Highly Elevated Risk.
Diastolic Blood Pressure. Evidence: 7/10. Source: PMID 27618452. -0.37 mmHg.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
This genotype represents the most common genetic profile globally, found in over 99% of the population. Because it lacks the rare T risk allele, it does not carry the elevated susceptibility to autoimmune disorders linked to this locus [1]. Specifically, the risk of developing celiac disease or systemic lupus erythematosus remains at the standard population baseline [1] [2]. However, large-scale genetic analyses indicate that the C allele is associated with a tiny, fraction-of-a-millimeter increase in diastolic blood pressure [3]. This blood pressure effect is extremely small and generally not clinically significant on its own. Overall, this genotype is considered highly favorable because it avoids the substantial autoimmune risks associated with the variant allele.
Typical baseline risk for celiac disease; Typical baseline risk for lupus.
Sample genotype: CT (Heterozygous)
Inheriting one copy of the T allele means carrying the HLA-DRB1*0301 tag, which is strongly linked to immune system hyper-reactivity. This genetic profile increases the odds of developing celiac disease by over six-fold compared to the general population [1]. It also more than doubles the risk of systemic lupus erythematosus and cutaneous lupus [2] [3]. The T allele is also associated with a higher risk of sarcoidosis, an inflammatory disease that affects multiple organs [4]. Conversely, this genotype is associated with a tiny reduction in diastolic blood pressure, though this effect is too small to offset the autoimmune risks [5]. While carrying this variant increases susceptibility, it is not a direct diagnosis, as many carriers never develop these conditions.
Increased risk of celiac disease; Increased risk of lupus.
Sample genotype: TT (Homozygous)
Having two copies of the T allele is extremely rare, occurring in less than 1 in 10,000 people globally. This genotype represents a double dose of the HLA-DRB1*0301 risk tag, which is strongly associated with autoimmune susceptibility. Individuals with this profile have a highly elevated risk of developing celiac disease [1] and systemic lupus erythematosus [2]. It is also associated with increased susceptibility to other immune-related conditions like cutaneous lupus and sarcoidosis [3] [4]. While some research suggests the risk for certain conditions like lupus may act dominantly, having two copies represents the highest genetic risk category at this locus. It is important to note that environmental triggers and other genetic factors are still required to initiate these diseases.
Highly elevated risk of celiac disease; Highly elevated risk of lupus.
Variants with shared genetic architecture
rs28383314 · HLA-DQA1 Gene · Chr 6 · Nasal Polyps Risk
rs9272346 · HLA-DQA1 Gene · Chr 6 · Type 1 Diabetes Risk
rs6927022 · HLA-DQA1 Gene · Chr 6 · Ulcerative Colitis Risk
Multiple common variants for celiac disease influencing immune gene expression.
Genome-wide association study identifies new susceptibility loci for cutaneous lupus erythematosus.
Content updated August 2026.
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