What you carry at this position in your DNA and what research says about it.
Breast Cancer Risk: 10/10 evidence, 44 publications.
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Sample genotype (not yours): G/G
Typical Breast Cancer Risk
Presence of two G alleles represents the baseline genetic risk for breast cancer. Estrogen receptor activity and breast cancer susceptibility remain at typical levels.
What this genotype means: Typical baseline risk for breast cancer; Typical estrogen receptor expression levels.
Sample genotype (not yours): A/A
Increased Breast Cancer Risk
Two copies of the A allele are associated with a moderate increase in breast cancer risk. This variant alters the regulatory enhancer region of the estrogen receptor gene.
What this genotype means: Moderately increased risk of breast cancer; Altered estrogen receptor expression in breast tissue.
Sample genotype (not yours): G/A
Slightly Increased Breast Cancer Risk
One copy of the A allele is associated with a modest increase in breast cancer susceptibility. This effect is primarily driven by altered estrogen receptor regulation in breast tissue.
What this genotype means: Modestly increased risk of breast cancer; Subtly altered estrogen receptor regulation.
Gene function and biological role
Gene Function: The LOC124901435 region is an uncharacterized genomic locus on chromosome 6. It is located approximately 180 kilobases upstream of the ESR1 gene, which encodes estrogen receptor alpha. This region acts as a distal transcriptional enhancer that regulates the expression of the estrogen receptor. Estrogen receptor alpha plays a central role in breast development, bone density maintenance, and the progression of hormone-sensitive cancers. Because of its regulatory influence on ESR1, genetic variations in this neighboring region are heavily studied for their impact on estrogen-dependent traits.
Variant Impact: Located in a non-coding, regulatory enhancer region upstream of the ESR1 gene, rs2046210 is a single nucleotide polymorphism. The change from a G to an A allele is thought to alter the binding of transcription factors, thereby modifying the expression levels of the estrogen receptor. This alteration in receptor expression can influence cellular sensitivity to estrogen, particularly in breast tissue. Consequently, this variant is one of the most widely replicated genetic markers associated with breast cancer susceptibility across diverse populations. It has also been linked to other estrogen-influenced physiological traits, such as bone mineral density and blood biomarker levels.
Key Insight: This variant does not alter the estrogen receptor protein itself, but instead acts like a dimmer switch, changing how much of the receptor is produced in breast tissue.
Location: ESR1. Chromosome 6 · 6q25.1 · 151.6 Mb
Estimated prevalence by population
Global 37.1%; European 43.1%; African 14.4%; East Asian 42.5%; South Asian 41.3%; Americas 48.7%; Ashkenazi 42.0%; Finnish 64.8%; Middle Eastern 30.0%; Amish 49.8%.
Estimated GG genotype frequency.
Global 44.4%; European 45.1%; African 47.1%; East Asian 45.4%; South Asian 45.9%; Americas 42.2%; Ashkenazi 45.6%; Finnish 31.4%; Middle Eastern 49.5%; Amish 41.6%.
Estimated GA genotype frequency.
Global 18.4%; European 11.8%; African 38.6%; East Asian 12.1%; South Asian 12.8%; Americas 9.1%; Ashkenazi 12.4%; Finnish 3.8%; Middle Eastern 20.4%; Amish 8.7%.
Estimated AA genotype frequency.
Showing effects for G/G genotype
Cancer & Oncology
Breast Cancer
Breast Cancer. Evidence: 10/10. Source: PMID 19219042. Typical Risk.
Nutrition & Metabolism
Blood Chemistry & Metabolites
Blood Phosphate Levels. Evidence: 6/10. Source: PMID 33462484. Typical.
Organ Systems
Bone, Joint & Connective Tissue Health
Bone Mineral Density. Evidence: 6/10. Source: PMID 37500982. Typical.
Showing effects for A/A genotype
Breast Cancer. Evidence: 10/10. Source: PMID 19219042. ~1.6x Risk.
Blood Phosphate Levels. Evidence: 6/10. Source: PMID 33462484. Higher.
Showing effects for G/A genotype
Breast Cancer. Evidence: 10/10. Source: PMID 19219042. ~1.3x to 1.4x Risk.
Blood Phosphate Levels. Evidence: 6/10. Source: PMID 33462484. Slightly Higher.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Inheriting two copies of the common G allele is associated with a typical, baseline risk of developing breast cancer. Large-scale genome-wide association studies have consistently shown that this genotype does not carry the elevated susceptibility seen with the A allele. This variant is located in an enhancer region that regulates the ESR1 gene, which encodes estrogen receptor alpha. With the GG genotype, estrogen receptor expression in breast tissue remains at typical levels. Additionally, this genotype is associated with normal baseline blood phosphate levels and typical bone mineral density. ClinVar assessments also confirm that this common variant is entirely harmless regarding rare estrogen resistance syndromes.
Typical baseline risk for breast cancer; Typical estrogen receptor expression levels.
Sample genotype: AA (Homozygous)
Double copies of the A allele are associated with a moderate increase in breast cancer susceptibility, with studies estimating a 1.6x higher risk in certain populations. This variant is located in a non-coding enhancer region upstream of the ESR1 gene, which encodes estrogen receptor alpha. The AA genotype is thought to enhance the activity of the ESR1 promoter, leading to increased expression of estrogen receptors in breast tissue. This increased receptor density can make breast cells more sensitive to estrogen-driven growth signals. The association is highly replicated in East Asian and European populations, though it appears to have little to no impact in women of African descent. Additionally, the AA genotype is associated with slightly higher blood phosphate levels and variations in bone mineral density.
Moderately increased risk of breast cancer; Altered estrogen receptor expression in breast tissue.
Sample genotype: GA (Heterozygous)
Possessing one copy of the A allele is linked to a modest increase in the risk of developing breast cancer, estimated at approximately 1.3x to 1.4x compared to the baseline genotype. This genetic variant lies within a regulatory enhancer region that influences the expression of the ESR1 gene, which encodes estrogen receptor alpha. The presence of the A allele is thought to subtly alter transcription factor binding, leading to modified estrogen receptor activity. This association has been widely replicated across multiple ethnic groups, including women of East Asian and European descent. However, studies suggest that this genetic risk factor has a much weaker or negligible effect in women of African ancestry. In addition to breast tissue effects, this genotype is associated with slightly altered blood phosphate levels.
Modestly increased risk of breast cancer; Subtly altered estrogen receptor regulation.
Variants with shared genetic architecture
rs2077647 · ESR1 Gene · Chr 6 · Blood Pressure
rs2234693 · ESR1 Gene · Chr 6 · Bone and Heart Health
rs2228480 · ESR1 Gene · Chr 6 · Estrogen Receptor Health
Content updated August 2026.
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