VDR rs11568816: What Your Genotype Means
The rs11568816 variant (historically known as the Cdx-2 polymorphism) is a single-nucleotide change located in the promoter region of the vitamin D receptor (VDR) gene. Scientific studies suggest this variant alters binding affinity for the CDX2 transcription factor, potentially influencing VDR expression levels. While research has linked this variant to statistical variations in bone mineral density and fracture risk, overall clinical evidence remains limited and varies across different ancestral groups.
What each genotype means
Typical vitamin D receptor profile
This genotype represents the common variant in the VDR gene promoter region. Research suggests this variant may influence how the vitamin D receptor regulates gene expression, potentially affecting calcium absorption and bone mineral density. Associations with bone health are complex and may vary based on individual vitamin D levels and overall lifestyle factors.
This genotype is common in many populations, though frequencies vary significantly by ancestry.
Typical vitamin D receptor profile
Carrying one copy of each allele means you have a mixed genetic profile for this VDR promoter variant. Studies indicate that VDR variants can influence how the body responds to vitamin D, which is essential for maintaining bone mineral density. Because the evidence linking this specific variant to clinical outcomes is limited, it is best viewed as one of many factors that contribute to bone health.
This heterozygous genotype is frequently observed across diverse global populations.
Potential altered receptor activity
This genotype is associated with the variant allele in the VDR gene promoter, which has been studied for its potential role in altered vitamin D binding and transcription. Some research suggests a link between this variant and a predisposition to reduced bone mineral density, though findings are inconsistent across different studies. You should discuss your bone health and vitamin D status with your healthcare provider to determine if any monitoring is appropriate.
This genotype is found in a significant portion of the population, with higher prevalence in European ancestries compared to African ancestries.
Genomic Location and the Cdx-2 Polymorphism
The single-nucleotide polymorphism rs11568816 is situated in the 5-prime upstream promoter region of the VDR gene on chromosome 12. In functional genomics literature, it is widely referred to as the Cdx-2 polymorphism. At this position, an adenine (A) nucleotide can be replaced by a guanine (G) nucleotide. Because it resides in the promoter region rather than a protein-coding exon, it does not alter the amino acid sequence of the receptor itself. Instead, in vitro studies indicate that the A allele alters a consensus binding motif for the caudal-type homeobox transcription factor CDX2. This change can modulate the transcription rate of the VDR gene in intestinal and epithelial tissues, thereby modifying the baseline amount of receptor protein available to respond to circulating vitamin D.
The Biological Role of the Vitamin D Receptor
The VDR gene encodes the vitamin D receptor, a nuclear hormone receptor that binds calcitriol (1,25-dihydroxyvitamin D3), the biologically active hormonal form of vitamin D as detailed in [VDR gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/vdr). Once activated by calcitriol, VDR heterodimerizes with retinoid X receptors and translocates to the cell nucleus. There, it binds specific DNA sequences known as vitamin D response elements to activate or suppress hundreds of downstream genes. This signaling cascade plays a critical role in mineral homeostasis, driving the intestinal absorption of calcium and phosphate necessary for maintaining healthy bone mineral density. Receptor levels modulated at the promoter level can therefore theoretically affect how effectively tissues capture calcium from dietary sources.
Scientific Research on Bone Density and Fracture Susceptibility
Multiple candidate gene association studies and meta-analyses have investigated rs11568816 for associations with bone mineral density (BMD) and fracture risk. Early studies in East Asian and European cohorts suggested that the G allele might be associated with lower transcriptional efficiency and a predisposition to reduced BMD at sites like the lumbar spine and femoral neck, as noted in review literature such as [Genetic regulation of bone mass and susceptibility to osteoporosis](https://genesdev.cshlp.org/content/20/18/2492.full.html). However, broader genome-wide association studies (GWAS) and diverse replication cohorts have reported mixed and inconclusive findings, with many cohorts observing no significant independent effect. As summarized in [OMIM Entry 601769 for VDR](https://www.omim.org/entry/601769), polymorphisms within the VDR gene exhibit modest effect sizes that are highly dependent on ancestral background, lifetime dietary calcium intake, and overall vitamin D sufficiency.
Population Frequency and Allele Patterns
The rs11568816 polymorphism is a common variant across global populations, though allele frequencies differ significantly by geographical ancestry. In populations of European descent, the minor allele frequency is approximately 0.40, making heterozygous and homozygous variant genotypes relatively widespread. In populations of African ancestry, the minor allele frequency is lower, at around 0.25, while East Asian populations also display distinct allele distributions according to public reference panels in [dbSNP](https://www.ncbi.nlm.nih.gov/snp/rs11568816). Because rs11568816 is often inherited alongside other classic VDR polymorphisms—such as FokI (rs2228570), BsmI (rs1544410), and TaqI (rs731236)—many researchers evaluate haplotypic patterns rather than considering rs11568816 in complete isolation.
Interpretation and Clinical Limitations
Carrying an allele associated with lower VDR transcription does not mean an individual has a medical diagnosis of osteopenia or osteoporosis. Polygenic factors, physical activity, hormonal levels, age, and dietary nutrition collectively drive skeletal strength far more than any single-nucleotide change. The clinical evidence for rs11568816 is classified as limited, meaning it cannot be used as a standalone diagnostic or predictive screening tool. Anyone evaluating their bone health or considering dietary adjustments should rely on validated clinical tests, such as dual-energy X-ray absorptiometry (DEXA) scans and serum 25-hydroxyvitamin D blood tests, under the guidance of a physician.
How common is this variant?
The minor allele frequency for rs11568816 is approximately 0.40 in populations of European ancestry and approximately 0.25 in populations of African ancestry, with common representation across global cohorts.
Frequently asked questions
Does having the rs11568816 variant mean I will develop osteoporosis?
No. The variant is simply a common genetic marker with limited statistical association in certain study populations. Bone density is a complex, multifactorial trait determined by physical activity, nutrition, hormones, and hundreds of other genetic factors.
Can rs11568816 tell me how much vitamin D I should supplement?
No genetic variant can determine your precise vitamin D requirement. Serum 25-hydroxyvitamin D blood tests interpreted by a healthcare professional are the standard method for evaluating vitamin D status and dosing.
What is the Cdx-2 site in the VDR gene?
The Cdx-2 site is a regulatory region in the VDR promoter where a protein named CDX2 binds to help activate gene transcription. The rs11568816 variant occurs directly within this binding site, potentially altering how efficiently the promoter responds.
How does rs11568816 differ from other VDR variants like FokI or BsmI?
While FokI (rs2228570) alters the protein structure of the receptor and BsmI (rs1544410) sits in an intron influencing RNA stability, rs11568816 is located in the gene's promoter region and regulates the initial transcription rate.
Sources & further reading
Educational information only, last refreshed 9/8/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Variant in the promoter region (Cdx2 site) of the vitamin D receptor gene associated with altered intestinal calcium absorption and bone mineral density.
This variant in the Vitamin D receptor gene is associated with susceptibility to Type 1 Diabetes and autoimmune thyroid disease.
Promoter polymorphism (Cdx2) in the VDR gene associated with bone mineral density and vitamin D metabolism.
Common polymorphism (TaqI variant) in the vitamin D receptor affecting mRNA stability and bone mineral density.
Known as the TaqI polymorphism, this variant is located in the 3' UTR of the VDR gene and is associated with altered mRNA stability, influencing vitamin D signaling, cancer cachexia susceptibility, and gastric cancer risk.
Variant in the VDR promoter (Cdx-2 binding site) associated with bone mineral density and calcium absorption efficiency.