VDR rs731236: Understanding the TaqI Polymorphism
The rs731236 variant is a common genetic change located in the VDR gene, which provides instructions for the vitamin D receptor. This polymorphism is frequently studied for its potential influence on how the body processes vitamin D and its association with various health conditions.
What each genotype means
Variable VDR receptor function
This genotype is sometimes referred to as the 't' allele homozygote in older literature. Research suggests this genotype may influence vitamin D receptor mRNA stability and ligand binding affinity, with some studies associating it with a protective effect against cognitive impairment, while others link it to increased susceptibility to certain autoimmune conditions or myopathy. Because these associations are often contradictory or population-specific, this result should not be used for medical diagnosis.
This genotype is common in European populations, where the C allele is frequently observed.
Variable VDR receptor function
This heterozygous genotype represents a mix of the two common alleles for the TaqI polymorphism. Studies have observed associations between this genotype and variations in quality of life metrics or susceptibility to certain chronic conditions, though findings remain inconsistent across different ethnic groups. It is important to recognize that these associations are statistical in nature and do not predict individual health outcomes.
This is a common genotype found in a significant portion of the general population across various ancestries.
Variable VDR receptor function
This genotype is sometimes referred to as the 'T' allele homozygote in older literature. Some research suggests this genotype may be associated with reduced vitamin D receptor mRNA stability or altered ligand affinity, potentially impacting how the body utilizes vitamin D for calcium homeostasis and cellular function. Associations with conditions like lumbar disc degenerative disease or fracture risk have been reported, but evidence is mixed and often depends on the specific population studied.
This genotype is frequently identified in population studies, particularly among individuals of European descent.
What is the rs731236 Variant?
The rs731236 variant, widely known in scientific literature as the TaqI polymorphism, is a single nucleotide polymorphism (SNP) located within the VDR gene. Specifically, it is found in exon 9 of the gene, which sits on chromosome 12. This variant involves a substitution of a thymine (T) base for a cytosine (C) base. Because it is a synonymous change, it does not alter the amino acid sequence of the resulting protein (Ile352Ile). However, researchers have long investigated whether this change might influence the stability of the VDR messenger RNA (mRNA) or affect the receptor's overall function in the body. As a 3' variant, it is often studied alongside other VDR polymorphisms to understand how genetic diversity in this region might contribute to differences in physiological responses to vitamin D.
The Role of the VDR Gene
The VDR gene encodes the vitamin D receptor, a protein that acts as a nuclear hormone receptor. When vitamin D binds to this receptor, the complex regulates the expression of numerous genes involved in essential biological processes. Its primary role is maintaining calcium homeostasis, which is critical for bone health and skeletal integrity. Beyond bone metabolism, the vitamin D receptor is involved in immune system modulation, cell growth, and the regulation of various metabolic pathways. It also functions as a receptor for lithocholic acid, a secondary bile acid. Because vitamin D is essential for so many bodily functions, variations in the VDR gene are frequently examined to see if they correlate with differences in how individuals absorb calcium or maintain adequate vitamin D levels in their blood.
Research Associations and Evidence Strength
Research into rs731236 has explored its potential links to a wide array of clinical conditions, including restless legs syndrome, polycystic ovary syndrome (PCOS), and bone mineral density. However, the evidence strength for these associations is generally considered limited. While some small-scale case-control studies have reported statistically significant differences in genotype frequencies between patients and healthy controls, these findings are often inconsistent across different populations. For instance, meta-analyses have sometimes failed to replicate initial findings regarding conditions like multiple sclerosis or Parkinson's disease. Because many of these studies are preliminary or limited to specific ethnic groups, it is difficult to draw broad conclusions about the variant's clinical impact. The scientific community continues to study this SNP, but it is not currently used as a diagnostic tool for any specific disease.
What You Can and Cannot Do With This Information
Genetic information regarding the rs731236 variant is primarily for educational purposes and should not be used to diagnose or treat any medical condition. If you have concerns about your vitamin D levels, bone health, or metabolic function, it is essential to consult with a healthcare professional. They can order appropriate blood tests to measure your actual vitamin D status and provide guidance based on your clinical history. You cannot use this genotype to predict your risk of disease or to determine specific dietary or supplement needs. Genetic variants are only one piece of a complex puzzle that includes diet, lifestyle, and environment. Always discuss any changes to your health regimen, including vitamin supplementation, with your doctor or a registered pharmacist to ensure they are safe and appropriate for your individual needs.
How common is this variant?
The minor allele frequency for rs731236 is approximately 0.35–0.45 across European populations, making it a relatively common variant.
Frequently asked questions
Is rs731236 a diagnostic test for vitamin D deficiency?
No, rs731236 is not a diagnostic test. Vitamin D deficiency is diagnosed through blood tests that measure the concentration of 25-hydroxyvitamin D in your serum, not by looking at your genetic code.
Does the TaqI polymorphism mean I need more vitamin D?
There is no clinical consensus that this variant requires a specific change in vitamin D intake. You should consult your doctor to determine if you need supplementation based on your blood levels and overall health.
Why do studies show different results for this SNP?
Genetic association studies can vary due to differences in study design, sample size, and the ethnic background of the participants. Because the effect of a single SNP is often very small, it is common for results to be inconsistent across different research groups.
Where can I find more information about the VDR gene?
You can find reliable, high-level information about the VDR gene and its functions on resources like MedlinePlus Genetics or the NCBI Gene database. These sites provide summaries of gene function and their roles in human health.
Sources & further reading
Educational information only, last refreshed 10/15/2026. 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.
Variant in the VDR promoter (Cdx-2 binding site) associated with bone mineral density and calcium absorption efficiency.
The Cdx2 polymorphism in the VDR promoter influences vitamin D receptor expression and is associated with bone mineral density.