CYP19A1 rs700518: Understanding the Aromatase Gene Variant
The rs700518 variant is a genetic polymorphism located within the CYP19A1 gene, which encodes the aromatase enzyme responsible for estrogen production. Research has investigated its potential influence on circulating estradiol levels and its association with bone density changes and treatment responses in breast cancer patients.
What each genotype means
Aromatase variant profile
This genotype is associated with variations in aromatase enzyme activity, which plays a key role in converting androgens to estrogens. Research has linked this variant to differences in circulating estradiol and insulin levels, though findings regarding specific health outcomes like breast cancer risk can be mixed or dependent on ancestry. Please discuss any concerns regarding hormone levels or health risks with your clinician.
This genotype is common, occurring in a significant portion of the global population alongside the AG and GG genotypes.
Aromatase variant profile
This genotype is associated with variations in aromatase enzyme activity, which plays a key role in converting androgens to estrogens. Research has linked this variant to differences in circulating estradiol and insulin levels, though findings regarding specific health outcomes like breast cancer risk can be mixed or dependent on ancestry. Please discuss any concerns regarding hormone levels or health risks with your clinician.
This is a common heterozygous genotype found across diverse global populations.
Aromatase variant profile
This genotype is associated with variations in aromatase enzyme activity, which plays a key role in converting androgens to estrogens. Some studies have specifically linked the GG genotype to differences in free estradiol index, SHBG, and insulin concentrations compared to other genotypes. Because associations with conditions like breast cancer risk can be ancestry-specific or limited in evidence, please discuss any health concerns with your clinician.
This genotype is common, occurring in a significant portion of the global population alongside the AA and AG genotypes.
What is rs700518 and Where is it Located?
The rs700518 variant is a single nucleotide polymorphism (SNP) situated within the CYP19A1 gene. This gene is located on chromosome 15 at position 15q21.2. In the context of genetic research, rs700518 is often referred to as the Val80 polymorphism, reflecting a specific amino acid change that can occur in the resulting protein structure. As a SNP, it represents a variation at a single position in the DNA sequence, which can differ between individuals. Because this variant sits within a gene critical for hormone regulation, scientists have long studied it to determine if these small sequence differences contribute to observable variations in human health, particularly regarding hormone-sensitive conditions.
The Role of the CYP19A1 Gene
The CYP19A1 gene provides instructions for creating the enzyme aromatase. Aromatase is a member of the cytochrome P450 superfamily of enzymes and plays a vital role in the body's endocrine system. Its primary function is to catalyze the final step in the biosynthesis of estrogens, such as estradiol, by converting androgens like androstenedione and testosterone. This process is essential for normal reproductive development and function in both men and women. Because estrogen levels are tightly regulated and influence many tissues—including bone, breast, and reproductive organs—the activity of the aromatase enzyme is a frequent subject of clinical research. Variations in the gene that codes for this enzyme may theoretically alter its efficiency or expression levels, potentially impacting how the body manages estrogen.
Research Associations and Evidence Strength
Research into rs700518 has primarily focused on its potential impact on clinical outcomes in patients with estrogen receptor-positive (ER+) breast cancer. Specifically, studies have examined whether this variant influences bone loss in women undergoing treatment with aromatase inhibitors, which are medications designed to block estrogen production. While some published research suggests a correlation between this genotype and the rate of bone mineral density loss or disease-free survival, the overall evidence strength remains limited. Associations between genetic variants and complex health outcomes are often influenced by multiple factors, including environment, lifestyle, and other genetic markers. Consequently, findings regarding rs700518 should be viewed as preliminary, and it is not currently used as a definitive diagnostic tool for predicting individual health risks or treatment responses.
Understanding Your Results
If you have received information about your rs700518 genotype, it is important to understand that this data represents a statistical association rather than a medical diagnosis. Genetic predispositions are only one piece of a much larger puzzle that includes your overall health history, lifestyle, and environmental factors. You cannot use this information to make independent medical decisions, such as starting or stopping a medication. If you are concerned about how your genetics might influence your response to a specific treatment, such as aromatase inhibitors, or if you have questions about your bone health, you should discuss these findings directly with your clinician or pharmacist. They are best equipped to interpret your genetic information within the context of your complete clinical profile and provide appropriate guidance.
How common is this variant?
The rs700518 variant is relatively common, with a minor allele frequency of approximately 0.45 across diverse global populations.
Frequently asked questions
Is rs700518 a diagnostic test for breast cancer?
No, rs700518 is not a diagnostic test for breast cancer. It is a genetic variant that has been studied for its potential association with treatment outcomes, but it does not determine whether an individual will develop the disease.
Can I use my rs700518 result to change my medication?
You should never change your medication based on genetic test results without consulting your doctor. Always discuss your genetic findings with your healthcare provider or pharmacist before making any changes to your treatment plan.
What does the CYP19A1 gene do?
The CYP19A1 gene provides the instructions for the aromatase enzyme. This enzyme is responsible for converting androgens into estrogens, which are hormones that play a key role in many bodily functions.
Why is the evidence for this variant considered limited?
Evidence is considered limited because studies on rs700518 have shown mixed results across different populations and clinical settings. More large-scale, peer-reviewed research is needed to confirm the clinical significance of this variant.
Sources & further reading
Educational information only, last refreshed 10/14/2026. Not medical advice — these associations describe population statistics, not individual predictions.
Curious what your genotype is for rs700518?
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 — $29Related variants in CYP19A1
This variant in the aromatase gene is associated with circulating estrogen levels and influences the timing of natural menopause and cardiovascular risk profiles in postmenopausal women.
This regulatory variant in the aromatase gene is associated with circulating estradiol levels and the timing of natural menopause.
Pathogenic variant causing aromatase deficiency characterized by female pseudohermaphroditism, maternal virilization during pregnancy, and absent pubertal development.
Intronic variant in the CYP19A1 gene associated with circulating estradiol and follicle-stimulating hormone (FSH) levels in men.
This variant in the aromatase gene is associated with variations in sex hormone levels and potential risk modulation for hormone-dependent reproductive cancers.
Affects aromatase activity, influencing efficacy and toxicity in hormone-sensitive cancer treatments.