What you carry at this position in your DNA and what research says about it.
Breast Cancer Prognosis: 5/10 evidence, 50 publications.
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Sample genotype (not yours): A/A
Lower Breast Cancer Mortality Risk
Carrying two copies of the common A allele is associated with more favorable survival outcomes in breast cancer. It also correlates with typical bone mineral density.
What this genotype means: Lower breast cancer mortality risk; Typical bone mineral density; Standard response to iron-chelation therapy.
Sample genotype (not yours): A/G
Typical Health Risks
Carrying one copy of the G allele results in intermediate vitamin D receptor activity. Overall risks for bone density and cancer prognosis remain near the population average.
What this genotype means: Typical breast cancer survival rates; Average bone mineral density; Standard response to iron-chelation therapy.
Sample genotype (not yours): G/G
Higher Breast Cancer Mortality Risk
Carrying two copies of the G allele is linked to a nearly three-fold increase in breast cancer-specific mortality and a higher risk of lower bone mineral density.
What this genotype means: Increased breast cancer mortality risk; Higher risk of osteopenia and osteoporosis; Enhanced response to deferasirox therapy.
Gene function and biological role
Gene Function: The VDR gene encodes the vitamin D receptor, a nuclear hormone receptor that binds to the active form of vitamin D [1]. This receptor acts as a transcription factor, regulating the expression of genes involved in calcium absorption, bone mineralization, and immune system function [2]. Beyond bone health, vitamin D signaling through this receptor plays a critical role in cell growth regulation, differentiation, and programmed cell death [3]. Variations in this gene can alter receptor expression levels and activity, influencing susceptibility to various chronic conditions and cancers [4].
Variant Impact: The rs731236 variant, commonly known as the TaqI polymorphism, is a synonymous genetic change located in exon 9 of the VDR gene [3]. Although it does not alter the amino acid sequence of the receptor, this genetic variation is in tight linkage with other regulatory regions and can influence mRNA stability and overall receptor abundance [1]. The major A allele corresponds to the traditional T allele, while the minor G allele corresponds to the C allele [5]. This specific change has been widely studied for its impact on bone mineral density, cancer survival outcomes, and immune-related conditions [4].
Key Insight: This synonymous genetic variant does not change the protein structure of the vitamin D receptor, yet it significantly influences how efficiently the body utilizes vitamin D for bone density and cancer cell regulation.
Location: VDR. Chromosome 12 · 12q13.11 · 47.8 Mb
Estimated prevalence by population
Global 44.5%; European 36.4%; African 51.0%; East Asian 87.9%; South Asian 45.0%; Americas 48.7%; Ashkenazi 41.1%; Finnish 44.8%; Middle Eastern 42.7%; Amish 52.2%.
Estimated AA genotype frequency.
Global 43.6%; European 47.9%; African 40.8%; East Asian 11.7%; South Asian 44.2%; Americas 42.2%; Ashkenazi 46.0%; Finnish 44.2%; Middle Eastern 45.3%; Amish 40.1%.
Estimated AG genotype frequency.
Global 11.8%; European 15.7%; African 8.2%; East Asian 0.4%; South Asian 10.9%; Americas 9.2%; Ashkenazi 12.9%; Finnish 10.9%; Middle Eastern 12.0%; Amish 7.7%.
Estimated GG genotype frequency.
Showing effects for A/A genotype
Cancer & Oncology
Cancer Prognosis & Treatment Outcome
Breast Cancer Prognosis. Evidence: 3/10. Source: PMID 23300018. Lower Mortality Risk.
Organ Systems
Bone, Joint & Connective Tissue Health
Bone Mineral Density. Evidence: 4/10. Source: PMID 30963970. Typical Density.
Respiratory Health
Asthma. Evidence: 3/10. Source: PMID 31654764. Typical Risk.
Pharmacogenomics
Drug Metabolism Enzyme Activity
Deferasirox Response. Evidence: 5/10. Source: PMID 30651574. Typical Response.
Showing effects for A/G genotype
Breast Cancer Prognosis. Evidence: 3/10. Source: PMID 23300018. Typical Risk.
Showing effects for G/G genotype
Breast Cancer Prognosis. Evidence: 3/10. Source: PMID 23300018. ~2.8x Higher Risk.
Bone Mineral Density. Evidence: 4/10. Source: PMID 30963970. Lower Bone Density.
Asthma. Evidence: 3/10. Source: PMID 31654764. Altered Risk.
Deferasirox Response. Evidence: 5/10. Source: PMID 30651574. Stronger Response.
What this genotype means for the people who carry it
Sample genotype: AA (Homozygous)
Clinical studies indicate that individuals with this genotype experience significantly lower breast cancer-specific mortality compared to those carrying the minor G allele [1]. This protective effect is thought to stem from more stable vitamin D receptor expression, which supports the hormone's natural ability to regulate cell growth and suppress tumor progression [2]. In terms of skeletal health, this genotype generally supports typical bone mineral density and presents a lower risk of developing osteopenia or osteoporosis [3]. Maintaining adequate vitamin D levels remains beneficial for overall cellular and bone health [4].
Lower breast cancer mortality risk; Typical bone mineral density; Standard response to iron-chelation therapy.
Sample genotype: AG (Heterozygous)
Having a heterozygous genotype means possessing one major A allele and one minor G allele, which typically results in intermediate receptor function [1]. Research on breast cancer survival suggests that this group does not experience the elevated mortality risks seen in double-copy minor allele carriers [2]. Bone mineral density studies show mixed results, with some cohorts exhibiting typical bone density while others show minor fluctuations depending on lifestyle factors [3]. Because vitamin D receptor activity is moderate, maintaining optimal vitamin D intake through diet and sun exposure is highly recommended to support skeletal strength [4].
Typical breast cancer survival rates; Average bone mineral density; Standard response to iron-chelation therapy.
Sample genotype: GG (Homozygous)
Somatic and epidemiological studies have shown that individuals with this homozygous minor genotype face an increased risk of breast cancer-specific mortality [1]. The genetic change may compromise the stability of the vitamin D receptor mRNA, leading to reduced receptor abundance and weaker anti-tumor signaling [2]. Additionally, this genotype is frequently associated with lower bone mineral density and an elevated susceptibility to osteopenia or osteoporosis [3]. On a positive note, some pharmacogenomic evidence suggests that this genotype may experience a better therapeutic response to the iron-chelating drug deferasirox [4].
Increased breast cancer mortality risk; Higher risk of osteopenia and osteoporosis; Enhanced response to deferasirox therapy.
Variants with shared genetic architecture
rs739837 · VDR Gene · Chr 12 · Skin Cancer Risk
rs11568820 · VDR Gene · Chr 12 · Bone Health and Density
rs1544410 · VDR Gene · Chr 12 · Osteoporosis Risk
Association of Vitamin D Gene Polymorphisms and Bone Mineral Density in Healthy young Saudi Females.
VDR and TNFSF11 polymorphisms are associated with osteoporosis in Thai patients.
Vitamin D receptor genotype rs731236 (Taq1) and breast cancer prognosis.
Content updated August 2026.
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