CYP2E1 rs3811805: Understanding This Regulatory Variant
The rs3811805 variant is a genetic change located in the promoter region of the CYP2E1 gene. It is associated with variations in how the body may metabolize certain substances, including acetaminophen, ethanol, and specific volatile anesthetics.
What each genotype means
Typical enzyme activity
This genotype represents the most common form of the CYP2E1 promoter region. Research suggests individuals with this profile typically exhibit standard transcriptional induction of the CYP2E1 enzyme, which is involved in the metabolism of substances like acetaminophen and ethanol. Please discuss any concerns regarding medication response or dosing with your clinician or pharmacist.
This is the most common genotype globally, though its frequency varies significantly by ancestry, being less common in populations where the T allele is highly prevalent.
Variable enzyme activity
Carrying one copy of the T allele, often associated with the CYP2E1*5B star allele, may influence the transcriptional regulation of the CYP2E1 enzyme. Studies on this variant have shown mixed results regarding its impact on the metabolism of substrates like acetaminophen and ethanol, and the clinical significance remains limited. Please consult your healthcare provider or pharmacist regarding how your genetic profile might relate to your specific medication needs.
This heterozygous genotype is found at varying frequencies, with higher prevalence observed in East Asian populations compared to European or African populations.
Altered enzyme activity
This genotype, which corresponds to the homozygous CYP2E1*5B variant, is linked to potential changes in the transcriptional induction of the CYP2E1 enzyme. While research indicates this variant can influence the metabolism of compounds such as acetaminophen, the evidence regarding its clinical impact is limited and may vary based on other genetic and environmental factors. You should discuss your medication management and any potential risks with your doctor or pharmacist.
This genotype is relatively rare in many populations but can reach frequencies of up to 25-30% in certain East Asian groups.
What is rs3811805?
The rs3811805 variant is a single nucleotide polymorphism (SNP) situated in the 5'-flanking regulatory region of the CYP2E1 gene on chromosome 10. In genetic nomenclature, this specific change is often referred to as c.-1055C>T. Because it resides in the promoter region—the "on-off switch" for a gene—it is hypothesized to influence how much of the CYP2E1 enzyme is produced by the liver. This variant is a defining feature of the CYP2E1*5B allele. While many SNPs are located within the protein-coding sequence of a gene, regulatory variants like rs3811805 are significant because they can alter the expression levels of an enzyme without changing the structure of the protein itself. Researchers study this site to understand why individuals may show different rates of metabolic activity when processing specific substrates.
The Role of the CYP2E1 Gene
The CYP2E1 gene encodes a member of the cytochrome P450 superfamily of enzymes. These enzymes are primarily responsible for the oxidative metabolism of a wide variety of substances, including endogenous compounds like fatty acids and exogenous substances such as drugs, solvents, and carcinogens. CYP2E1 is particularly well-known for its role in the metabolism of ethanol and the activation of certain pro-carcinogens. It also plays a part in the metabolism of common medications, most notably acetaminophen, as well as isoniazid and chlorzoxazone. Because of its involvement in producing reactive metabolites, the activity of this enzyme is a subject of interest in toxicology and pharmacology. Variations in the gene's expression can theoretically lead to differences in how quickly these substances are cleared from the body or how much reactive byproduct is generated during the metabolic process.
Research and Evidence Strength
Current scientific evidence regarding the clinical impact of rs3811805 is considered limited. While studies have investigated its association with altered transcriptional induction and variable metabolism of substrates like acetaminophen and ethanol, the findings are often mixed or context-dependent. Some research has explored links between CYP2E1 variants and susceptibility to alcohol-related liver disease or certain cancers, but these associations are not universally consistent across different study populations. Because the evidence is not yet robust enough to support standardized clinical guidelines, there are currently no widely accepted recommendations for adjusting medication dosages based solely on this genotype. The scientific community continues to evaluate how regulatory variants interact with environmental factors and other genetic markers to influence overall metabolic health. As with any pharmacogenomic marker, the clinical significance remains an area of active investigation rather than established medical practice.
Population Frequency
The frequency of the rs3811805 variant varies significantly across different ancestral groups. Data indicates that the minor allele frequency (MAF) is approximately 0.02 to 0.05 in European and African populations. In contrast, the frequency is notably higher in East Asian populations, where it can reach 0.25 to 0.30. This wide disparity highlights the importance of considering ancestry when interpreting genetic data. Because the variant is much more common in some populations than others, researchers must account for these differences to avoid bias in genetic studies. Understanding these frequency patterns helps scientists design more inclusive research and provides context for why certain metabolic traits might appear more frequently in specific geographic or ethnic groups.
What This Means for You
If you have received information about your rs3811805 genotype, it is important to understand that this is a research-level finding rather than a diagnostic tool. Genetic variants in the CYP2E1 gene do not act in isolation; your actual metabolic rate is influenced by a complex interplay of other genes, your age, liver health, diet, and current medications. You cannot use this information to predict how you will react to a specific drug or to make decisions about your health. If you are concerned about how your body processes medications, the most appropriate step is to consult with your physician or a clinical pharmacist. They can provide guidance based on your full medical history and current clinical guidelines, which are far more reliable than individual SNP results. Always discuss any changes to your medication regimen with a qualified healthcare professional.
How common is this variant?
The minor allele frequency for rs3811805 is approximately 0.02-0.05 in European and African populations, while it is significantly higher in East Asian populations, reaching up to 0.25-0.30.
Frequently asked questions
Is rs3811805 a diagnostic test for drug metabolism?
No, rs3811805 is not a diagnostic test. It is a genetic variant studied in research settings, and current evidence is insufficient to use it for clinical decision-making or predicting individual drug responses.
Should I change my medication based on my CYP2E1 genotype?
You should never change your medication based on a genetic test result without consulting your doctor. Always speak with your healthcare provider or a pharmacist before making any adjustments to your prescribed treatments.
Does this variant cause liver disease?
While some studies have explored potential links between CYP2E1 variants and liver health, there is no definitive evidence that rs3811805 directly causes liver disease. Liver health is complex and influenced by many environmental and genetic factors.
Why is the frequency of this variant different in East Asians?
Genetic variation often differs between populations due to historical migration, natural selection, and genetic drift. The higher frequency of this variant in East Asian populations is a documented observation, but it does not imply a specific health outcome.
Sources & further reading
Educational information only, last refreshed 9/14/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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