PTGS2 rs689466: Understanding the -1195G>A Promoter Variant
The rs689466 variant is a single-nucleotide polymorphism located in the promoter region of the PTGS2 gene, which encodes the COX-2 enzyme. Research suggests this variant may influence transcriptional activity and is statistically associated with varying levels of susceptibility to certain inflammatory conditions and cancers.
What each genotype means
Altered promoter activity
You carry two copies of the A allele (historically referred to as -1195A) in the promoter region of the PTGS2 gene, which encodes the COX-2 enzyme involved in prostaglandin synthesis. Research shows this genotype creates an atypical c-MYB transcription factor binding site that may alter baseline COX-2 expression, with some studies reporting modest associations with inflammatory bowel diseases and colorectal neoplasia, although findings across diverse populations remain mixed and limited. These statistical associations do not indicate disease, and routine lifestyle choices or preventive screenings should be discussed with your healthcare provider.
Carried by approximately 2% to 3% of individuals of European ancestry, but present in roughly 25% of individuals of East Asian ancestry where the A allele is significantly more frequent.
Intermediate promoter activity
You carry one copy of the common G allele and one copy of the A allele (frequently noted in scientific literature as -1195G>A) in the PTGS2 promoter. This heterozygous genotype is associated with intermediate transcriptional activation of COX-2 compared to homozygous individuals. Evidence regarding colorectal neoplasia susceptibility and inflammatory condition risks linked to this variant is modest, inconsistent across ancestral cohorts, and does not serve as a diagnostic marker.
Carried by roughly 25% to 30% of people of European ancestry and nearly 50% of individuals of East Asian ancestry.
Typical promoter activity
You carry two copies of the G allele (commonly referenced as -1195G) in the PTGS2 promoter region. This genotype represents the standard transcriptional baseline for COX-2 expression without the altered c-MYB regulatory motif introduced by the A allele. In most published association studies, carrying GG corresponds to baseline inflammatory and colorectal neoplasia risks typical of the general population.
Carried by roughly 70% of individuals of European descent, but present in only about 25% of individuals of East Asian ancestry.
What is rs689466 and Where is it Located?
The rs689466 variant is a common genetic change located in the promoter region of the PTGS2 gene on chromosome 1. Specifically, it is often referred to as the -1195G>A polymorphism. This region is critical because it acts as a control switch for the gene, determining how much of the COX-2 protein is produced by the cell. By altering a binding site for transcription factors, such as c-Myb, this single-letter change can potentially disrupt the normal regulatory signals that tell the cell when to turn the gene on or off. Because it sits in a regulatory area rather than the protein-coding sequence itself, it does not change the structure of the COX-2 enzyme, but rather the quantity of the enzyme that is manufactured in response to stimuli.
The Role of the PTGS2 Gene
The PTGS2 gene provides instructions for making the enzyme cyclooxygenase-2, commonly known as COX-2. This enzyme plays a central role in the body's inflammatory response by catalyzing the production of prostaglandins, which are lipid compounds that signal pain, fever, and inflammation. While COX-2 is often induced by pro-inflammatory stimuli, it is also involved in normal physiological processes. Because inflammation is a complex biological process, the regulation of COX-2 is tightly controlled. When this regulation is disrupted—either through environmental factors or genetic variants like rs689466—it can lead to either an overproduction or underproduction of prostaglandins. This imbalance is why researchers study PTGS2 variants in the context of chronic inflammatory diseases and various forms of neoplasia, where persistent inflammation is a known contributing factor.
Research Associations and Evidence Strength
Scientific literature regarding rs689466 is extensive but often shows mixed results, leading to a classification of limited or moderate evidence strength. Numerous studies have investigated its association with colorectal cancer, lung cancer, and inflammatory bowel diseases. Some meta-analyses suggest that the G-allele may be associated with different risks compared to the A-allele, but these findings are frequently dependent on the population studied. For instance, some research indicates that the variant may influence cancer risk in specific ethnic groups while showing no significant effect in others. Furthermore, the biological impact of this SNP is often influenced by linkage disequilibrium, where it is inherited alongside other nearby variants, making it difficult to isolate the specific effect of rs689466 alone. Because of these conflicting results across different cohorts, the clinical utility of this variant for predicting individual disease risk remains limited.
Population Frequency
The frequency of the rs689466 alleles varies significantly across different global populations. Data from large-scale genomic databases indicate that the minor allele frequency is approximately 0.15 in European populations, while it is much higher, around 0.50, in East Asian populations. This substantial difference in allele distribution is a primary reason why researchers often observe different statistical associations when comparing studies conducted in different parts of the world. Understanding these ancestral differences is essential for interpreting genetic data, as a variant that is common in one group may be relatively rare in another, potentially leading to different baseline risks for associated conditions.
What You Can and Cannot Do With This Information
Genetic information regarding rs689466 is intended for educational purposes and should not be used for medical diagnosis or personal health management. While research explores the link between this variant and inflammatory susceptibility, it is only one of many factors—including diet, lifestyle, and other genetic markers—that contribute to health outcomes. You cannot use this information to predict your personal risk of developing cancer or inflammatory disease. If you are concerned about your health or have questions about how your genetics might interact with medications like NSAIDs, which target the COX-2 pathway, you should discuss these topics with your clinician or a pharmacist. They can provide guidance based on your full medical history rather than a single genetic variant.
How common is this variant?
The rs689466 variant shows significant ancestral variation, with a minor allele frequency of approximately 0.15 in Europeans and 0.50 in East Asians.
Frequently asked questions
Is rs689466 a diagnostic test for cancer?
No, rs689466 is not a diagnostic test. It is a genetic variant studied for its statistical association with disease risk in large populations, and it cannot determine if an individual will develop a specific condition.
Does this variant affect how I respond to aspirin?
Some research suggests that PTGS2 variants may influence how individuals respond to NSAIDs like aspirin, but this is an area of ongoing study. You should consult your doctor or pharmacist before making any changes to your medication regimen.
Why do study results for this SNP often conflict?
Conflicting results often arise due to differences in study design, sample sizes, and the diverse genetic backgrounds of the populations being studied. Additionally, this SNP is often inherited with other nearby variants, which can complicate the interpretation of its individual effect.
Can I change my risk associated with this variant?
Genetic variants are inherited and cannot be changed. However, health outcomes are influenced by many modifiable factors, such as diet, exercise, and regular medical screenings, which are far more impactful than any single SNP.
Sources & further reading
Educational information only, last refreshed 9/12/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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