ESR1 rs9340799: What Your Genotype Means
The rs9340799 variant is a common single nucleotide polymorphism (SNP) located within the ESR1 gene, which encodes the estrogen receptor alpha protein. Research has investigated its potential associations with conditions such as endometriosis and variations in cognitive performance during aging.
What each genotype means
Typical estrogen receptor variant
Research suggests that individuals with the AA genotype may have a lower statistical risk for developing endometriosis compared to those with other genotypes at this position. Some studies have also explored links between this genotype and cognitive function during aging, though findings across different populations remain inconsistent.
This genotype is common, though specific frequencies vary significantly by global ancestry.
Mixed estrogen receptor variant
The AG genotype represents a heterozygous state that may be associated with intermediate statistical outcomes regarding endometriosis risk. Studies investigating cognitive aging and other estrogen-related health markers have yielded mixed results for this genotype, indicating that individual risk is likely influenced by a complex interplay of additional genetic and environmental factors.
This genotype is frequently observed across many global populations.
Elevated risk association profile
Some research has observed that the GG genotype is statistically associated with a higher risk of endometriosis. Additionally, in the context of postmenopausal bone health, some studies have noted that individuals with this genotype may respond differently to hormone therapy compared to those with the AA genotype. These associations are based on observational data and do not confirm a diagnosis; please discuss any personal health concerns or clinical questions with your healthcare provider.
While less common than the A-allele genotypes in many groups, the GG genotype is found in a notable proportion of the population worldwide.
Understanding the rs9340799 Variant
The rs9340799 variant is a specific change in the DNA sequence of the ESR1 gene, often referred to in scientific literature as the XbaI polymorphism. A SNP, or single nucleotide polymorphism, represents a variation at a single position in the DNA building blocks. In the case of rs9340799, the variation involves the substitution of one nucleotide for another, which can influence how the gene is expressed or how the resulting protein functions. Because this variant is located within a gene responsible for hormone signaling, researchers have long been interested in whether these small genetic differences contribute to individual variations in health outcomes, particularly those related to estrogen-sensitive tissues and processes.
The Role of the ESR1 Gene
The ESR1 gene provides instructions for making the estrogen receptor alpha protein. This protein acts as a transcription factor, meaning it binds to specific regions of DNA to turn genes on or off in response to estrogen. Estrogen receptors are found throughout the body, including in the reproductive system, the brain, and bone tissue. By regulating gene expression, the estrogen receptor alpha plays a critical role in reproductive health, bone density maintenance, and cognitive function. Because estrogen signaling is so widespread, variations in the ESR1 gene, such as rs9340799, are frequently studied to see if they alter the sensitivity or efficiency of these hormonal pathways, potentially impacting how different individuals respond to estrogen levels throughout their lives.
Research Associations and Evidence Strength
Scientific findings regarding rs9340799 are mixed and often context-dependent. Some studies have reported associations between this variant and an increased risk of endometriosis or challenges with in vitro fertilization outcomes. In the realm of cognitive health, results have been inconsistent; while some studies have suggested links to cognitive decline or memory performance in specific cohorts, others have found no independent association. It is important to note that the evidence for these links is considered limited. Many studies are small, and associations often vary significantly based on the ancestry of the participants or the presence of other genetic factors, such as the APOE gene. Because of these conflicting results, the clinical significance of this variant remains an area of active scientific inquiry rather than a established diagnostic marker.
Population Frequency
The rs9340799 variant is considered a common polymorphism, meaning it is found frequently across diverse human populations. While specific allele frequencies can fluctuate between different ethnic and geographic groups, the variant is widespread enough that most individuals will carry at least one copy of the common alleles. This high prevalence is one reason why it is frequently included in large-scale genetic association studies. However, the frequency of the specific genotypes (AA, AG, or GG) does not necessarily correlate with the severity of any associated health outcomes, as the biological impact of the variant is likely influenced by a complex interplay of environmental factors, lifestyle, and other genetic modifiers.
Interpreting Your Genetic Information
Genetic information regarding variants like rs9340799 should be viewed as a piece of a much larger puzzle. Because the evidence linking this SNP to specific health conditions is limited and inconsistent, it cannot be used to predict an individual's health or diagnose a condition. If you have received results regarding this variant, it is essential to remember that genetics is only one factor among many, including environment and overall health history, that influence well-being. You should never use this information to make medical decisions or alter treatments. If you have concerns about endometriosis, cognitive health, or fertility, the most effective approach is to discuss your symptoms and family history with a qualified healthcare provider who can offer personalized guidance based on clinical evidence.
How common is this variant?
The rs9340799 variant is a common polymorphism found across diverse global populations, with the G and A alleles appearing at significant frequencies in most studied groups.
Frequently asked questions
Can I use my rs9340799 result to diagnose endometriosis?
No. This variant is not a diagnostic tool for endometriosis. The association between this SNP and the condition is limited and inconsistent across studies, and it cannot be used to confirm or rule out a diagnosis.
Does this variant mean I will have memory problems as I age?
Not necessarily. While some research has explored links between ESR1 variants and cognitive aging, the results are mixed. Many factors, including lifestyle, education, and other genetic markers, play a much larger role in cognitive health.
Should I change my medication based on this SNP?
No. You should never change or stop any medication based on genetic test results without consulting your doctor or pharmacist. Genetic variants like this are not currently used to guide clinical dosing for hormone-related therapies.
Why do different studies show different results for this variant?
Genetic association studies often differ due to variations in study design, sample size, and the ancestry of the participants. Additionally, complex conditions like endometriosis are influenced by many genes and environmental factors, making it difficult to isolate the effect of a single SNP.
Sources & further reading
Educational information only, last refreshed 10/27/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Estrogen receptor 1 variant associated with altered circulating estradiol levels, follicular maturation, and variability in age at natural menopause.
Variant in estrogen receptor 1 associated with variation in female reproductive timing, including age at menarche and natural menopause onset.
Common polymorphism in estrogen receptor alpha (ESR1) affecting target tissue responsiveness to estrogen, recurrent pregnancy loss risk, and bone-reproductive axis interactions.
Estrogen receptor 1 regulatory variant associated with variation in timing of menarche and bone density response to sex hormones.
Estrogen receptor 1 missense and intronic regulatory variation associated with ovarian responsiveness and fertilization rates in assisted reproductive technology.
ESR1 variant linked to variation in age at natural menopause.