What you carry at this position in your DNA and what research says about it.
Spondylitis Risk: 7/10 evidence, 25 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): G/G
Higher Risk of Spondylitis
Two copies of the G allele are linked to an increased risk of ankylosing spondylitis and psoriasis. This genotype is also associated with slightly lower blood pressure.
What this genotype means: Increased risk of ankylosing spondylitis; Higher susceptibility to psoriasis; Slightly lower blood pressure.
Sample genotype (not yours): C/C
Typical Risk of Spondylitis
Two copies of the C allele provide protection against ankylosing spondylitis and psoriasis, though they are linked to slightly higher blood pressure.
What this genotype means: Typical baseline risk of ankylosing spondylitis; Lower susceptibility to psoriasis; Slightly higher blood pressure.
Sample genotype (not yours): G/C
Having one copy of the G allele is linked to an increased risk of ankylosing spondylitis and psoriasis, with typical blood pressure levels.
What this genotype means: Increased risk of ankylosing spondylitis; Higher susceptibility to psoriasis; Typical blood pressure levels.
Gene function and biological role
Gene Function: The ERAP1 gene encodes endoplasmic reticulum aminopeptidase 1, an enzyme essential for trimming peptides to the correct length before they are presented on the cell surface by immune molecules [1]. This peptide-trimming process is critical for the immune system to distinguish between self and foreign proteins [2]. When ERAP1 function is altered, it can lead to the presentation of abnormal peptides, triggering autoimmune reactions [3]. This gene is particularly known for its strong genetic interaction with HLA-B27, a major histocompatibility complex class I molecule [4]. Together, variations in these genes significantly influence susceptibility to chronic inflammatory joint and skin diseases [5].
Variant Impact: The rs27044 variant is a missense mutation in the ERAP1 gene that results in an amino acid substitution from glutamine to glutamic acid at position 730 [6]. This specific change alters the enzymatic activity and peptide-trimming kinetics of the ERAP1 protein [2]. Consequently, the altered enzyme changes the pool of peptides presented to immune cells, which can drive inflammatory pathways [3]. This variant is widely studied for its role in predisposing individuals to autoimmune and joint-related disorders [7]. Additionally, it has been associated with subtle variations in systemic blood pressure regulation [8].
Key Insight: This variant acts as a genetic trade-off where the allele that increases the risk of inflammatory joint and skin conditions actually correlates with slightly lower blood pressure.
Location: ERAP1. Chromosome 5 · 5q15 · 96.8 Mb
Estimated prevalence by population
Global 8.9%; European 7.7%; African 8.3%; East Asian 20.9%; South Asian 7.7%; Americas 11.4%; Ashkenazi 9.0%; Finnish 9.9%; Middle Eastern 13.2%; Amish 8.7%.
Estimated GG genotype frequency.
Global 41.4%; European 40.1%; African 41.1%; East Asian 49.6%; South Asian 40.2%; Americas 44.7%; Ashkenazi 42.1%; Finnish 43.1%; Middle Eastern 46.3%; Amish 41.6%.
Estimated GC genotype frequency.
Global 49.7%; European 52.3%; African 50.6%; East Asian 29.5%; South Asian 52.1%; Americas 43.9%; Ashkenazi 48.9%; Finnish 47.0%; Middle Eastern 40.5%; Amish 49.7%.
Estimated CC genotype frequency.
Showing effects for G/G genotype
Immunity & Inflammation
Autoimmune Diseases
Ankylosing Spondylitis. Evidence: 5/10. Source: PMID 21229357. ~1.4x Higher Risk.
Organ Systems
Skin & Hair Conditions
Psoriasis. Evidence: 6/10. Source: PMID 25854761. Increased Risk.
Cardiovascular & Metabolic
Hypertension
Systolic Blood Pressure. Evidence: 7/10. Source: PMID 33230300. Slightly Lower.
Diastolic Blood Pressure. Evidence: 7/10. Source: PMID 33230300. Slightly Lower.
Showing effects for C/C genotype
Ankylosing Spondylitis. Evidence: 5/10. Source: PMID 21229357. Typical Risk.
Psoriasis. Evidence: 6/10. Source: PMID 25854761. Typical Risk.
Systolic Blood Pressure. Evidence: 7/10. Source: PMID 33230300. Slightly Higher.
Diastolic Blood Pressure. Evidence: 7/10. Source: PMID 33230300. Slightly Higher.
Showing effects for G/C genotype
Systolic Blood Pressure. Evidence: 7/10. Source: PMID 33230300. Typical.
Diastolic Blood Pressure. Evidence: 7/10. Source: PMID 33230300. Typical.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Carrying two copies of the G allele is associated with a 1.4-fold increased risk of developing ankylosing spondylitis, a chronic inflammatory arthritis affecting the spine [1]. This risk is particularly pronounced in individuals who are also positive for the HLA-B27 immune marker [2]. The G allele also correlates with a higher susceptibility to psoriasis, an autoimmune skin condition [3]. On a molecular level, the G allele alters how the ERAP1 enzyme trims proteins, which can trigger inflammatory pathways in the joints and skin [4]. Interestingly, this genotype is associated with slightly lower systolic and diastolic blood pressure, representing a minor cardiovascular benefit [5]. However, the clinical impact on blood pressure is very small compared to the joint and skin inflammation risks.
Increased risk of ankylosing spondylitis; Higher susceptibility to psoriasis; Slightly lower blood pressure.
Sample genotype: CC (Homozygous)
Carrying two copies of the C allele is associated with a normal, baseline risk of developing ankylosing spondylitis [1]. This genotype helps protect against chronic spinal inflammation, even in individuals who carry other genetic risk factors like HLA-B27 [2]. It is also associated with a lower risk of developing psoriasis compared to carriers of the G allele [3]. The C allele allows the ERAP1 enzyme to trim peptides in a manner that is less likely to trigger autoimmune responses [4]. However, this genotype is linked to a very minor increase in both systolic and diastolic blood pressure [5]. This small cardiovascular trade-off is generally considered minor compared to the significant protection against chronic inflammatory diseases.
Typical baseline risk of ankylosing spondylitis; Lower susceptibility to psoriasis; Slightly higher blood pressure.
Sample genotype: GC (Heterozygous)
Carrying one copy of the G allele is associated with an elevated risk of ankylosing spondylitis, similar to carrying two copies [1]. This inflammatory joint condition primarily affects the spine and sacroiliac joints, especially in those who carry the HLA-B27 marker [2]. The G allele also contributes to a higher risk of developing psoriasis [3]. Because the G allele alters the peptide-trimming function of the ERAP1 enzyme, it can lead to immune system overactivation [4]. Regarding cardiovascular health, this heterozygous genotype is associated with typical blood pressure levels, as the blood-pressure-lowering effect of the G allele is balanced by the blood-pressure-raising effect of the C allele [5].
Increased risk of ankylosing spondylitis; Higher susceptibility to psoriasis; Typical blood pressure levels.
Variants with shared genetic architecture
rs30187 · ERAP1 Gene · Chr 5 · Ankylosing Spondylitis Risk
rs17482078 · ERAP1 Gene · Chr 5 · Inflammatory Disease Risk
rs26653 · ERAP1 Gene · Chr 5 · Autoimmune Joint Risk
Functional variants of ERAP1 gene are associated with HLA-B27 positive spondyloarthritis.
Associations between ERAP1 polymorphisms and ankylosing spondylitis susceptibility: a meta-analysis.
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