What you carry at this position in your DNA and what research says about it.
Breast Cancer Risk: 9/10 evidence, 44 publications.
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Sample genotype (not yours): A/A
Elevated Breast Cancer Risk
Carrying two copies of the A allele is associated with a 1.7-fold increase in the risk of developing estrogen receptor-positive breast cancer. It is also linked to reduced survival outcomes during sunitinib cancer treatment.
What this genotype means: 1.7x higher risk of ER+ breast cancer; Decreased survival on sunitinib therapy.
Sample genotype (not yours): A/G
Moderately Increased Breast Cancer Risk
Carrying one copy of the A allele is associated with a moderate, 1.3-fold increase in the risk of developing estrogen receptor-positive breast cancer. It may also offer some protection against heart damage if treated with the cancer drug sunitinib.
What this genotype means: 1.3x higher risk of ER+ breast cancer; Decreased likelihood of sunitinib-induced heart damage.
Sample genotype (not yours): G/G
Typical Breast Cancer Risk
Carrying two copies of the G allele is associated with baseline levels of FGFR2 expression and a typical risk of breast cancer. There is also a very slight increase in the risk of atrial fibrillation, though the overall impact is minimal.
What this genotype means: Typical breast cancer risk; Slightly higher atrial fibrillation risk.
Gene function and biological role
Gene Function: The FGFR2 gene encodes fibroblast growth factor receptor 2, a protein that plays a critical role in cell growth, division, and tissue repair [1]. It is highly active in breast tissue and is essential for normal mammary gland development [2]. Variations in this gene can alter its expression levels, affecting how breast cells respond to growth signals [3]. Because of its central role in cell proliferation, FGFR2 is one of the most heavily studied genes in breast cancer susceptibility [1].
Variant Impact: The rs2981582 variant is located in an intron of the FGFR2 gene and acts as a regulatory switch [1]. The A allele increases the expression of FGFR2 in breast tissue, making cells more sensitive to growth factors and promoting cell division [2]. This increased activity is particularly linked to estrogen receptor-positive breast cancer [3]. Conversely, the G allele is associated with typical expression levels and baseline risk [1].
Key Insight: The rs2981582 variant is the single most significant common genetic marker associated with breast cancer risk discovered in large-scale genomic studies. While it increases risk, it is primarily associated with estrogen receptor-positive (ER+) tumors rather than ER-negative ones.
Location: FGFR2. Chromosome 10 · 10q26.13 · 121.6 Mb
Estimated prevalence by population
Global 17.5%; European 15.0%; African 23.0%; East Asian 9.6%; South Asian 12.1%; Americas 16.8%; Ashkenazi 18.0%; Finnish 17.8%; Middle Eastern 18.6%; Amish 31.8%.
Estimated AA genotype frequency.
Global 48.1%; European 47.5%; African 49.9%; East Asian 42.8%; South Asian 45.4%; Americas 48.4%; Ashkenazi 48.9%; Finnish 48.8%; Middle Eastern 49.1%; Amish 49.2%.
Estimated AG genotype frequency.
Global 34.4%; European 37.6%; African 27.1%; East Asian 47.5%; South Asian 42.5%; Americas 34.8%; Ashkenazi 33.1%; Finnish 33.4%; Middle Eastern 32.3%; Amish 19.0%.
Estimated GG genotype frequency.
Showing effects for A/A genotype
Cancer & Oncology
Breast Cancer
Breast Cancer. Evidence: 9/10. Source: PMID 17529967. 1.7x Higher Risk.
Cardiovascular & Metabolic
Heart Rhythm & Conduction
Atrial Fibrillation. Evidence: 6/10. Source: PMID 40050429. Typical Risk.
Pharmacogenomics
Chemotherapy Response
Sunitinib Response. Evidence: 5/10. Source: PMID 23462807. Decreased Survival.
Showing effects for A/G genotype
Breast Cancer. Evidence: 9/10. Source: PMID 17529967. 1.3x Higher Risk.
Atrial Fibrillation. Evidence: 6/10. Source: PMID 40050429. Slightly Higher Risk.
Sunitinib Response. Evidence: 5/10. Source: PMID 23462807. Lower Heart Damage.
Showing effects for G/G genotype
Breast Cancer. Evidence: 9/10. Source: PMID 17529967. Typical Risk.
Sunitinib Response. Evidence: 5/10. Source: PMID 23462807. Typical Response.
What this genotype means for the people who carry it
Sample genotype: AA (Homozygous)
Inheriting two copies of the A risk allele represents the highest risk category at this genetic locus, with studies showing a 1.7-fold increase in susceptibility to estrogen receptor-positive breast cancer [1]. The presence of two A alleles significantly enhances the activity of the FGFR2 gene, leading to increased cell growth signals in breast tissue [2]. This association has been robustly confirmed across diverse populations, making it one of the most reliable genetic markers for breast cancer risk [3]. Furthermore, in patients receiving sunitinib therapy for metastatic renal cell carcinoma, this genotype is associated with decreased overall survival [4]. Conversely, these individuals have a lower risk of atrial fibrillation compared to those carrying the G allele [5]. Understanding this genetic profile can help guide personalized screening schedules and risk-reduction strategies in consultation with a physician.
1.7x higher risk of ER+ breast cancer; Decreased survival on sunitinib therapy.
Sample genotype: AG (Heterozygous)
Possessing one copy of the A risk allele is linked to a moderately elevated susceptibility to breast cancer, particularly the estrogen receptor-positive subtype [1]. This genetic variation acts as an enhancer, slightly boosting the expression of the FGFR2 gene and encouraging breast cell proliferation [2]. Multiple international studies have replicated this finding, estimating the risk increase at approximately 1.3 times the baseline rate [3]. In the context of cancer treatment, however, this genotype has been associated with a decreased likelihood of experiencing heart damage when taking the medication sunitinib [4]. Despite this specific drug-response benefit, the primary health impact remains the moderate increase in breast cancer susceptibility.
1.3x higher risk of ER+ breast cancer; Decreased likelihood of sunitinib-induced heart damage.
Sample genotype: GG (Homozygous)
Having the G/G genotype means possessing the typical, protective version of this genetic marker. Large-scale genome-wide association studies have consistently shown that this genotype does not elevate the risk of estrogen receptor-positive breast cancer [1]. The G allele maintains normal regulatory control over the FGFR2 gene, preventing the overexpression that can lead to uncontrolled cell division in breast tissue [2]. While some research suggests a tiny increase in the risk of atrial fibrillation associated with the G allele, the effect size is extremely small and generally considered clinically minor [3]. For patients undergoing sunitinib therapy for cancer, this genotype is associated with a standard, typical response and survival profile [4]. Overall, this genetic profile represents the baseline standard for breast health at this specific locus.
Typical breast cancer risk; Slightly higher atrial fibrillation risk.
Variants with shared genetic architecture
rs1219648 · FGFR2 Gene · Chr 10 · Breast Cancer Risk
rs2981579 · FGFR2 Gene · Chr 10 · Breast Cancer Risk
rs2981575 · FGFR2 Gene · Chr 10 · Breast Cancer and Prostate Risk
Genome-wide association study identifies novel breast cancer susceptibility loci.
Content updated August 2026.
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