ESR1 rs1126513: What Your Genotype Means
The rs1126513 variant is a specific genetic change located within the ESR1 gene. It has been studied for its potential associations with variations in female reproductive timing, such as the age at which menstruation begins and the onset of natural menopause.
What each genotype means
Typical reproductive timing
You carry two copies of the major A allele for this ESR1 variant. In population association studies, this genotype is considered the baseline profile and is not linked to minor allele shifts in pubertal or natural menopausal timing. However, overall reproductive timing is polygenic and strongly shaped by lifestyle and environmental factors.
Carried by roughly 40% to 45% of individuals of European ancestry and about 60% to 65% of East Asian populations.
Subtle variation in timing
You carry one copy of the G minor allele. Large-scale association studies report that carrying an alternate allele at this ESR1 locus has a very small statistical influence on reproductive milestones such as ages at menarche and menopause. Because the overall scientific evidence remains limited and effect sizes are subtle, this genotype alone does not determine your reproductive lifespan.
Carried by approximately 45% of individuals of European ancestry and roughly 30% to 35% of East Asian individuals.
Subtle variation in timing
You carry two copies of the G minor allele at this ESR1 site. While research indicates a statistical correlation with slight variations in the timing of pubertal onset and menopause, the association evidence remains limited and explains only a minor fraction of overall trait variation. Individual reproductive health and timing depend on hundreds of genes as well as lifestyle and general health factors.
Carried by about 10% to 15% of people of European ancestry and approximately 3% to 5% of East Asian individuals.
Understanding the rs1126513 Variant
The rs1126513 variant is a single nucleotide polymorphism (SNP) located within the ESR1 gene. In genetics, a SNP represents a variation at a single position in the DNA sequence among individuals. This specific variant is situated in a region of the genome that influences how the body processes estrogen signals. Because it is located within a gene that is critical for reproductive health, researchers have investigated whether this specific change in the DNA code correlates with observable differences in reproductive milestones. It is important to note that rs1126513 is just one of many variations within the ESR1 gene, and its presence does not determine a specific health outcome on its own. Instead, it is viewed as a marker that may contribute to the natural diversity seen in human reproductive biology across different populations.
The Role of the ESR1 Gene
The ESR1 gene provides instructions for making a protein called estrogen receptor alpha. This protein acts as a receptor, meaning it binds to estrogen—a primary female sex hormone—and helps regulate the activity of many other genes. By acting as a chemical messenger, the estrogen receptor alpha protein plays a vital role in growth, metabolism, and sexual development. It is expressed in various tissues throughout the body, including the reproductive system, bone, and breast tissue. Because it is so central to how the body responds to estrogen, variations in the ESR1 gene are frequently studied in the context of reproductive health, bone density, and certain hormone-sensitive conditions. Understanding the function of this gene helps researchers explain why hormonal experiences, such as the timing of menstrual cycles or the transition into menopause, can vary significantly from one person to another.
Research and Evidence Strength
Scientific research into rs1126513 has primarily focused on its association with reproductive traits, such as the age at menarche and the timing of natural menopause. These studies often utilize genome-wide association studies (GWAS) to look for statistical links between specific genetic markers and these life events. While some studies have identified potential correlations, the evidence strength for rs1126513 remains limited. Reproductive timing is a complex trait influenced by a combination of many different genes, environmental factors, and lifestyle choices. Consequently, a single SNP like rs1126513 typically has a very small effect size, meaning it only accounts for a tiny fraction of the variation observed in the population. Current findings should be interpreted as statistical associations rather than direct causes, and further research is required to fully understand the biological mechanisms, if any, that link this specific variant to reproductive outcomes.
Population Frequency
The frequency of the rs1126513 variant varies across different ancestral groups. Data indicates that the minor allele frequency is approximately 0.35 in European populations and approximately 0.20 in East Asian populations. These differences highlight that genetic variants are not distributed uniformly across the globe. Because frequency can differ significantly based on ancestry, findings from one population may not necessarily apply to another. Researchers consider these frequency differences when designing studies to ensure that genetic associations are robust and reproducible across diverse groups of people.
Interpreting Your Genetic Information
If you have information about your genotype for rs1126513, it is important to understand what this means in a practical sense. This variant is associated with natural biological variation in reproductive timing, not with a medical condition or a diagnostic outcome. You cannot use this information to predict your specific reproductive health or to make medical decisions. Genetic associations are based on large groups of people and do not provide a personalized forecast for an individual. If you have questions about your reproductive health, menstrual cycle, or menopause, the most appropriate step is to consult with a healthcare professional, such as a gynecologist or a primary care physician. They can provide guidance based on your personal health history, physical examinations, and clinical testing, which are far more informative than any single genetic variant.
How common is this variant?
The minor allele frequency for rs1126513 is approximately 0.35 in European populations and approximately 0.20 in East Asian populations.
Frequently asked questions
Does the rs1126513 variant cause early menopause?
No, the rs1126513 variant does not cause early menopause. It is a genetic marker that has been statistically associated with variations in reproductive timing, but it is not a diagnostic tool or a direct cause of any medical condition.
Can I use this SNP to predict my fertility?
No, you cannot use this SNP to predict your fertility. Reproductive health is influenced by many complex factors, and this variant has only a very small, limited association with reproductive traits.
Is this variant related to breast cancer risk?
While the ESR1 gene is involved in breast health, rs1126513 is primarily studied in the context of reproductive timing. You should not use this information to assess your personal risk for cancer; please consult a doctor for appropriate screening.
Why do different populations have different frequencies of this SNP?
Genetic variation is naturally distributed differently across human populations due to historical migration, evolutionary pressures, and genetic drift. It is common for the frequency of specific SNPs to vary significantly between different ancestral groups.
Sources & further reading
Educational information only, last refreshed 10/13/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This variant in the estrogen receptor 1 gene is associated with an increased risk of endometriosis and may influence cognitive aging.
Estrogen receptor 1 variant associated with altered circulating estradiol levels, follicular maturation, and variability in age at natural menopause.
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.