CYP19A1 rs28566535: What Your Genotype Means
The rs28566535 variant is a common genetic change located within the CYP19A1 gene, which provides instructions for the aromatase enzyme. Research has investigated this variant for potential associations with circulating sex hormone levels and susceptibility to hormone-dependent conditions.
What each genotype means
Typical aromatase gene profile
This genotype represents the major allele configuration for this variant. Research in some populations has compared this to the minor allele to study potential associations with hormone-dependent conditions, but results are mixed and often show no significant difference in risk.
This is the most common genotype observed in most global populations.
Heterozygous aromatase variant
You carry one copy of the minor allele for this variant. Studies have investigated whether this variation influences aromatase activity or susceptibility to hormone-related conditions, but current evidence is limited and inconsistent across different ethnic groups.
This genotype is found at moderate frequencies in many populations, though exact percentages vary by ancestry.
Minor allele homozygous profile
You carry two copies of the minor allele. Some research in specific cohorts has suggested an association between this genotype and an increased risk of breast cancer in the presence of proliferative fibrocystic conditions, while other studies have found no significant association at all. Because the evidence is limited and conflicting, this result should not be used to predict individual health outcomes.
This genotype is less common than the major allele homozygote and is observed at varying frequencies depending on ancestral background.
Understanding the Variant and Its Location
The variant rs28566535 is a single nucleotide polymorphism (SNP) situated on chromosome 15 within the CYP19A1 gene. In genetics, a SNP represents a variation at a single position in the DNA sequence among individuals. This specific variant is located in a region of the genome that has been studied for its potential influence on how the body regulates hormone production. Because it sits within the CYP19A1 gene, researchers often examine it to see if it affects the expression or efficiency of the protein that the gene encodes. It is categorized as a common variant, meaning it appears frequently across various human populations, rather than being a rare mutation that might cause a specific, severe genetic disorder.
The Role of the CYP19A1 Gene
The CYP19A1 gene is responsible for producing an enzyme known as aromatase. Aromatase plays a critical role in the endocrine system by catalyzing the final step in the biosynthesis of estrogens from androgens. Specifically, it converts androgens like testosterone and androstenedione into estrogens such as estradiol and estrone. This process is essential for maintaining the balance of sex hormones in both men and women. Because aromatase is central to estrogen production, variations in the CYP19A1 gene are of significant interest to scientists studying hormone-dependent processes, including reproductive health, bone density, and the development of certain types of cancers that rely on estrogen for growth.
Research Associations and Evidence Strength
Scientific literature has explored the relationship between rs28566535 and various health outcomes, particularly those related to hormone levels. Some studies have investigated whether this variant correlates with differences in circulating estrogen or androgen levels, or with the risk of conditions like breast or endometrial cancer. However, the evidence strength for these associations is currently considered limited. While some early studies suggested potential links, results have been mixed across different populations and study designs. It is important to note that genetic associations observed in research do not imply a direct cause-and-effect relationship for any individual. Many factors, including environment, lifestyle, and other genetic markers, contribute to complex health traits, and the clinical significance of this specific SNP remains a subject of ongoing scientific inquiry.
Population Frequency
The rs28566535 variant is classified as a common polymorphism. Data from large-scale genomic databases indicate that it is present at significant frequencies across diverse ancestral groups, making it a standard feature of human genetic variation rather than a rare occurrence.
Interpreting Genetic Information
Understanding your genetic profile can be an educational experience, but it is vital to approach this information with perspective. The presence of a specific genotype for rs28566535 does not serve as a medical diagnosis or a predictor of future health. Because the evidence linking this variant to specific health outcomes is limited and often inconsistent, it should not be used to make personal health decisions or lifestyle changes. If you have concerns about your hormone levels, reproductive health, or cancer risk, the most appropriate step is to consult with a qualified healthcare professional. They can provide context based on your full medical history, physical examinations, and validated clinical testing, which are far more reliable than individual SNP data.
How common is this variant?
The rs28566535 variant is a common polymorphism found across diverse global populations, with a minor allele frequency typically reported in the range of 0.25.
Frequently asked questions
Does having the C allele for rs28566535 mean I will get cancer?
No. Genetic variants like rs28566535 are only one of many factors that influence health. The evidence linking this variant to cancer risk is limited and inconsistent, and it cannot be used to predict or diagnose disease.
Can I use this information to change my hormone levels?
No. You should never attempt to alter your hormone levels based on genetic data. If you have concerns about your hormone health, please consult a doctor or endocrinologist for appropriate testing and guidance.
Is rs28566535 the same as aromatase deficiency?
No. Aromatase deficiency is a rare condition caused by specific, often severe, mutations in the CYP19A1 gene that significantly impair enzyme function. rs28566535 is a common variant that does not cause this condition.
Where can I find more information about my specific genetic results?
If you have received genetic testing results, you should discuss them with a certified genetic counselor or your primary care physician. They can help you interpret the findings within the context of your overall health.
Sources & further reading
Educational information only, last refreshed 9/29/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Aromatase gene polymorphism associated with circulating estradiol levels and altered susceptibility to postmenopausal osteoporosis and breast cancer.
Aromatase single-nucleotide variant modulating estrogen biosynthesis efficiency and postmenopausal hormone levels.
Intronic aromatase variant linked to variation in circulating estradiol levels and timing of natural menopause.
This variant in the aromatase gene is associated with cardiovascular risk in postmenopausal women and shows linkage disequilibrium with markers of hypertension.
This SNP forms a haplotype with rs10046 that has been clinically associated with hypertension in postmenopausal populations.
Intronic regulatory variant in CYP19A1 associated with circulating estradiol levels and timing of natural menopause.