ERAP1 rs2704675: Immune Presentation and Autoimmune Risk
The genetic variant rs2704675 is a common missense single nucleotide polymorphism situated in the ERAP1 gene. It alters the structure of endoplasmic reticulum aminopeptidase 1, an enzyme responsible for trimming peptides before presentation on MHC class I molecules. Population studies associate this variant with altered susceptibility to inflammatory conditions such as ankylosing spondylitis and psoriasis, especially in individuals carrying specific HLA alleles.
What each genotype means
Standard ERAP1 activity
This genotype represents the homozygous state for the major allele of the rs2704675 variant. Research indicates that ERAP1 variants influence how the immune system processes peptides for presentation to MHC class I molecules, which can modulate susceptibility to autoimmune conditions like ankylosing spondylitis in individuals who also carry specific HLA risk alleles. This genotype is common and is generally considered the baseline for comparison in genetic association studies.
This is a common genotype found across most global populations, with frequencies typically reflecting the high prevalence of the C allele.
Intermediate ERAP1 activity
This heterozygous genotype contains one copy of each allele for the rs2704675 variant. The presence of the T allele may influence the efficiency of peptide trimming within the endoplasmic reticulum, potentially altering the repertoire of peptides presented by HLA molecules. Associations with autoimmune risk are often dependent on the presence of other genetic factors, such as HLA-B27 or HLA-C, rather than this variant alone.
This genotype is frequently observed in diverse populations, consistent with the common occurrence of both alleles in the general population.
Altered ERAP1 activity
This homozygous genotype for the T allele is associated with variations in ERAP1 enzymatic function, which plays a role in the antigen processing pathway. Studies suggest that specific ERAP1 variants can modify the risk of developing ankylosing spondylitis or psoriasis, particularly through interactions with HLA-B27 or HLA-C. The clinical significance of this genotype is highly dependent on an individual's broader genetic background and immune profile.
This genotype is present at moderate frequencies worldwide, though its prevalence varies significantly by ancestral background.
What Is rs2704675 and Where Is It Located?
The single nucleotide polymorphism rs2704675 represents an alterable point in the human genome located within the ERAP1 gene on chromosome 5. As cataloged in resources like [NCBI dbSNP](https://www.ncbi.nlm.nih.gov/snp/rs2704675), rs2704675 is a missense variation, meaning that the substitution of one nucleotide for another results in a single amino acid change in the resulting protein. The variant allele changes how the amino acid chain is assembled, modifying the physical structure and flexibility of the mature enzyme. In genetic studies, researchers track both the major and minor alleles at this position to assess how these structural shifts correlate with cellular traits and complex inflammatory disease patterns. Rather than causing catastrophic dysfunction or single-gene disease, rs2704675 is a common, naturally occurring polymorphism found throughout global populations that fine-tunes how the immune system processes molecular signals.
The Biological Role of the ERAP1 Gene
The ERAP1 gene provides the biological instructions to make endoplasmic reticulum aminopeptidase 1, an enzyme anchored inside the endoplasmic reticulum of human cells. According to [MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/erap1/), this protein plays an indispensable role in antigen processing. Specifically, ERAP1 acts like molecular shears, trimming longer precursor peptides down to precise lengths—typically 8 to 10 amino acids—so they can stably fit into the binding groove of Major Histocompatibility Complex (MHC) class I molecules. Once loaded, these complexes travel to the cell surface, allowing CD8+ cytotoxic T cells to inspect the cell's internal environment. If ERAP1 trims peptides too aggressively or leaves them too long, the repertoire of presented antigens shifts. This delicate trimming mechanism ensures that the immune system recognizes intracellular pathogens and malignant cells while preventing self-reactive immune destruction.
Disease Associations and Strength of Evidence
Genome-wide association studies cataloged in the [GWAS Catalog](https://www.ebi.ac.uk/gwas/search?query=rs2704675) provide moderate evidence linking rs2704675 and adjacent ERAP1 loci with inflammatory and autoimmune conditions, most prominently ankylosing spondylitis and psoriasis. As documented in publications indexed on [PubMed](https://pubmed.ncbi.nlm.nih.gov/?term=rs2704675), the association is marked by epistasis: the effect of ERAP1 variation strongly depends on which MHC class I alleles an individual carries. For example, ERAP1 variants modify the risk of ankylosing spondylitis primarily in individuals who are positive for HLA-B27, and psoriasis risk in those carrying HLA-C*06:02. When ERAP1 alters its trimming kinetics, it generates an altered immunopeptidome that can either trigger or shield against aberrant cytotoxic T-cell responses. However, because rs2704675 operates alongside other closely linked ERAP1 variants in coordinated haplotypes, it represents an incremental modifier of risk rather than an independent diagnostic cause.
Understanding Genotypes in Clinical and Lifestyle Context
Discovering your rs2704675 genotype from direct-to-consumer or clinical genetic testing provides insight into personal biology, but it cannot predict health outcomes on its own. While the variant is cataloged in databases such as [ClinVar](https://www.ncbi.nlm.nih.gov/clinvar/?term=rs2704675), common non-HLA variations like rs2704675 contribute only fractional shifts in relative risk for autoimmune conditions. An individual can carry the higher-attention genotype and never develop joint inflammation, psoriasis, or any immune-mediated condition. Conversely, individuals with neutral or protective genotypes can still develop inflammatory diseases due to other genetic risk factors, HLA status, microbiome composition, and environmental exposures. This variant cannot diagnose any medical condition, nor can it identify specific dietary or lifestyle interventions. Anyone experiencing chronic back pain, joint stiffness, or persistent skin rashes should discuss their symptoms with a physician or rheumatologist rather than relying on genetic data.
How common is this variant?
The rs2704675 variant is common worldwide, with minor allele frequencies typically ranging between 0.25 and 0.45 across major continental populations in large genomic databases like gnomAD.
Frequently asked questions
Does having the rs2704675 variant mean I will get ankylosing spondylitis?
No. The rs2704675 variant is an incremental risk modifier, not a causative mutation. The vast majority of people with this variant never develop ankylosing spondylitis, especially in the absence of the primary genetic risk factor, HLA-B27.
Can rs2704675 testing be used to diagnose psoriasis or joint pain?
No. Single-variant testing for rs2704675 has no diagnostic value on its own. Autoimmune and inflammatory conditions are diagnosed through physical examination, imaging, personal history, and specialized clinical lab work performed by medical professionals.
How does ERAP1 interact with HLA genes?
ERAP1 acts upstream of HLA proteins by trimming peptide fragments in the endoplasmic reticulum until they fit inside the HLA groove. Because the shaped peptides are directly handed to HLA molecules, variations in ERAP1 alter the exact molecular presentation that the immune system inspects.
Are there medications or supplements that target the rs2704675 variant?
There are currently no approved dietary supplements or medications designed to target specific ERAP1 genotypes. Although pharmaceutical researchers are investigating ERAP1 inhibitors for autoimmune diseases and oncology, these therapies remain in investigational phases.
Sources & further reading
Educational information only, last refreshed 9/6/2026. Not medical advice — these associations describe population statistics, not individual predictions.
Curious what your genotype is for rs2704675?
Upload a raw DNA file from 23andMe, AncestryDNA, MyHeritage, or FamilyTreeDNA and see this variant — plus thousands more — interpreted in your full report.
Get my report — $29