What you carry at this position in your DNA and what research says about it.
Breast Cancer Risk: 10/10 evidence, 46 publications.
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Sample genotype (not yours): A/A
Typical Breast Cancer Risk
Carrying two copies of the common A allele is associated with a typical baseline risk of breast cancer. This genotype does not carry the elevated risk associated with the G variant.
What this genotype means: Typical baseline risk of breast cancer; Typical baseline risk of ER+ breast cancer; Typical dental development risk.
Sample genotype (not yours): A/G
Moderately Increased Breast Cancer Risk
Carrying one copy of the G allele is associated with a moderately increased risk of breast cancer, particularly estrogen receptor-positive types.
What this genotype means: 1.20x increased risk of breast cancer; Increased risk of ER+ breast cancer; Slightly increased risk of premolar tooth agenesis.
Sample genotype (not yours): G/G
Elevated Breast Cancer Risk
Carrying two copies of the G allele is associated with a significantly elevated risk of breast cancer, particularly estrogen receptor-positive types.
What this genotype means: 1.64x increased risk of breast cancer; Elevated risk of ER+ breast cancer; Slightly increased risk of premolar tooth agenesis.
Gene function and biological role
Gene Function: The FGFR2 gene encodes fibroblast growth factor receptor 2, a member of a highly conserved family of receptor tyrosine kinases. This protein plays a critical role in essential cellular processes including cell survival, growth, division, and migration. It is particularly vital during embryonic development, bone growth, and the normal development of mammary glands. Alterations in FGFR2 expression or signaling pathways are heavily implicated in the development of various cancers, most notably breast cancer.
Variant Impact: The rs1219648 variant is an intronic single nucleotide polymorphism located within intron 2 of the FGFR2 gene. Although it does not directly alter the amino acid sequence of the protein, it resides in a highly active transcriptional regulatory region. The G allele is part of a specific genetic haplotype that enhances the transcription and expression of the FGFR2 gene. This increased expression leads to elevated receptor levels and enhanced downstream signaling, which increases susceptibility to hormone-receptor-positive breast cancers.
Key Insight: This variant is located in a non-coding region of the gene but acts like an amplifier, increasing the overall production of the FGFR2 protein to drive cancer susceptibility.
Location: FGFR2. Chromosome 10 · 10q26.13 · 121.6 Mb
Estimated prevalence by population
Global 35.0%; European 36.6%; African 32.9%; East Asian 38.7%; South Asian 37.5%; Americas 34.7%; Ashkenazi 34.1%; Finnish 32.4%; Middle Eastern 32.3%; Amish 20.4%.
Estimated AA genotype frequency.
Global 48.2%; European 47.8%; African 48.9%; East Asian 47.0%; South Asian 47.5%; Americas 48.4%; Ashkenazi 48.6%; Finnish 49.0%; Middle Eastern 49.1%; Amish 49.5%.
Estimated AG genotype frequency.
Global 16.7%; European 15.6%; African 18.2%; East Asian 14.3%; South Asian 15.0%; Americas 16.9%; Ashkenazi 17.3%; Finnish 18.6%; Middle Eastern 18.7%; Amish 30.1%.
Estimated GG genotype frequency.
Showing effects for A/A genotype
Cancer & Oncology
Breast Cancer
Breast Cancer. Evidence: 10/10. Source: PMID 17529973. Typical Risk.
ER-Positive Breast Cancer. Evidence: 7/10. Source: PMID 32366738. Typical Risk.
Gynecological Cancers
Ovarian Cancer. Evidence: 8/10. Source: PMID 36819030. Typical Risk.
Organ Systems
Dental & Oral Health
Tooth Agenesis. Evidence: 3/10. Source: PMID 23169889. Typical Risk.
Endocrine & Reproductive
Female Reproductive Health & Fertility
Endometriosis. Evidence: 3/10. Source: PMID 18535005. Typical Risk.
Showing effects for A/G genotype
Breast Cancer. Evidence: 10/10. Source: PMID 17529973. ~1.20x Increased Risk.
ER-Positive Breast Cancer. Evidence: 7/10. Source: PMID 32366738. Increased Risk.
Tooth Agenesis. Evidence: 3/10. Source: PMID 23169889. ~1.80x Increased Risk.
Showing effects for G/G genotype
Breast Cancer. Evidence: 10/10. Source: PMID 17529973. ~1.64x Increased Risk.
ER-Positive Breast Cancer. Evidence: 7/10. Source: PMID 32366738. Elevated Risk.
What this genotype means for the people who carry it
Sample genotype: AA (Homozygous)
Having the A/A genotype means you carry two copies of the common, non-risk allele at this location in the FGFR2 gene. Large-scale genome-wide association studies have consistently shown that individuals with this genotype have the lowest risk of developing breast cancer compared to those carrying one or two copies of the G allele. Specifically, this genotype is associated with a typical baseline risk, avoiding the 20% to 64% increase in risk observed in G allele carriers. The A/A genotype is also associated with a typical risk of estrogen receptor-positive (ER+) breast cancer. Additionally, studies have shown no increased risk of tooth agenesis or other dental development anomalies for this genotype. It is important to remember that breast cancer risk is influenced by many genetic and lifestyle factors, and having a typical genetic risk does not mean zero risk.
Typical baseline risk of breast cancer; Typical baseline risk of ER+ breast cancer; Typical dental development risk.
Sample genotype: AG (Heterozygous)
Having the A/G genotype means you carry one copy of the risk-associated G allele in the FGFR2 gene. This genotype is linked to a moderately increased risk of breast cancer, with studies estimating about a 1.20-fold increase in risk compared to the typical A/A genotype. This association is particularly strong for postmenopausal women and for estrogen receptor-positive (ER+) breast cancer subtypes. The G allele is thought to increase the transcription of the FGFR2 gene, leading to higher levels of the receptor and increased cell proliferation signaling. Some research also suggests a potential link between this variant and a slightly higher risk of premolar tooth agenesis. However, this variant is not associated with an increased risk of endometriosis or ovarian cancer. Knowing this risk can help inform discussions with healthcare providers about standard screening guidelines.
1.20x increased risk of breast cancer; Increased risk of ER+ breast cancer; Slightly increased risk of premolar tooth agenesis.
Sample genotype: GG (Homozygous)
Having the G/G genotype means you carry two copies of the risk-associated G allele in the FGFR2 gene. This genotype is associated with the highest risk of breast cancer at this locus, with studies reporting an approximate 1.64-fold increase in risk compared to the typical A/A genotype. This elevated risk is most pronounced for estrogen receptor-positive (ER+) breast cancers, which are highly responsive to hormone levels. The biological mechanism involves increased transcription of the FGFR2 gene, which enhances cellular growth signals in breast tissue. Additionally, carrying the G allele has been associated with a higher risk of premolar tooth agenesis. However, large-scale studies have confirmed that this variant does not increase the risk of endometriosis or ovarian cancer. This genotype represents one of the most well-replicated low-penetrance breast cancer risk variants identified in genome-wide association studies.
1.64x increased risk of breast cancer; Elevated risk of ER+ breast cancer; Slightly increased risk of premolar tooth agenesis.
Variants with shared genetic architecture
rs2981579 · FGFR2 Gene · Chr 10 · Breast Cancer Risk
rs2981582 · FGFR2 Gene · Chr 10 · Breast Cancer Risk
rs2981575 · FGFR2 Gene · Chr 10 · Breast Cancer and Prostate Risk
Content updated August 2026.
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