CYP2B6 rs3211371: What Your Genotype Means
The rs3211371 variant is a specific genetic change located within the CYP2B6 gene, which encodes an enzyme responsible for metabolizing various medications. This variant is associated with the CYP2B6*5 allele and is studied for its potential influence on how the body processes certain drugs.
What each genotype means
Normal enzyme expression
This genotype represents the most common form of the CYP2B6 gene, often referred to as the wild-type or *1 allele. Individuals with this profile typically exhibit standard CYP2B6 protein expression and catalytic activity. Please discuss any concerns regarding medication metabolism or dosing with your clinician or pharmacist.
This is the most frequent genotype observed across all major global populations.
Reduced enzyme expression
This genotype includes one copy of the variant allele, also known as the CYP2B6*5 allele, which involves an arginine to cysteine change at amino acid position 487. Research suggests this variant may influence CYP2B6 protein expression, potentially leading to altered metabolism of certain medications. Please consult your healthcare provider or pharmacist to discuss how this may affect your specific medication response.
This genotype is found at varying frequencies, with allele frequencies for the T variant reported between 9-14% in Caucasian populations and 2-9% in Black or African American populations.
Altered enzyme expression
This genotype consists of two copies of the variant allele, which is associated with the CYP2B6*5 haplotype. Studies indicate that this variant can reduce CYP2B6 protein expression in both the liver and the brain, which may impact the processing of specific drugs. You should discuss the clinical implications of this genotype with your doctor or pharmacist before starting or adjusting any medications metabolized by this enzyme.
This homozygous genotype is less common than the heterozygous form and its frequency varies significantly across different ancestral groups.
Understanding the rs3211371 Variant
The rs3211371 variant is a single nucleotide polymorphism (SNP) located on chromosome 19. In scientific literature, it is often referred to as 1459C>T, indicating a change from a cytosine to a thymine base at a specific position in the DNA sequence. This genetic change results in an amino acid substitution in the protein, specifically changing arginine to cysteine at position 487 (R487C). This specific change defines the CYP2B6*5 allele. Because the CYP2B6 gene is highly polymorphic, meaning it has many variations, researchers track these specific SNPs to understand how different versions of the gene might affect enzyme function. While rs3211371 is a well-documented marker, it is often analyzed alongside other variants to determine a person's complete CYP2B6 haplotype, which provides a more comprehensive picture of their genetic profile regarding this enzyme.
The Role of the CYP2B6 Gene
The CYP2B6 gene provides instructions for making an enzyme that belongs to the cytochrome P450 superfamily. These enzymes are primarily found in the liver and act as biological catalysts, helping the body break down, or metabolize, a wide range of substances. This includes not only toxins and environmental chemicals but also many clinically important medications. Drugs metabolized by CYP2B6 include certain anti-cancer agents like cyclophosphamide and ifosfamide, as well as medications used for anesthesia and HIV treatment, such as efavirenz. Because this enzyme is so central to drug clearance, variations in the gene can lead to differences in how quickly or slowly a person processes these medications. Understanding these genetic differences is a key focus of pharmacogenomics, a field that aims to tailor medical treatments to an individual's unique genetic makeup to improve efficacy and reduce the risk of adverse drug reactions.
Research and Clinical Evidence
Research into rs3211371 has primarily focused on its impact on the catalytic activity and expression of the CYP2B6 enzyme. Studies have suggested that while the R487C change associated with the *5 allele may have a mild or negligible effect on the enzyme's direct catalytic activity, it may influence protein expression levels in liver tissue. The evidence strength for this variant is considered moderate, as its clinical impact is often context-dependent and can be influenced by the presence of other co-occurring variants. For instance, when rs3211371 appears in combination with other SNPs, it can form more complex haplotypes that have more pronounced effects on drug metabolism. Because of this complexity, researchers emphasize that genetic testing for a single variant like rs3211371 is rarely sufficient to predict a patient's clinical response to a drug. Instead, it is viewed as one piece of a larger puzzle in understanding individual metabolic variability.
What You Can Do With This Information
If you have received information about your rs3211371 genotype, it is important to understand that this is a research-level finding rather than a diagnostic tool. Genetic variants in the CYP2B6 gene are complex, and their clinical significance depends on many factors, including the specific medication being prescribed, your overall health, and other genetic markers. You cannot use this information to self-diagnose or make decisions about your medications. If you are concerned about how your body might respond to a specific drug, the most appropriate step is to discuss your genetic profile with your clinician or a pharmacist. They are trained to interpret pharmacogenomic data in the context of your full medical history and can provide guidance on whether further testing or dosage adjustments are necessary. Always consult a healthcare professional before making any changes to your prescribed treatment plan.
How common is this variant?
The frequency of the CYP2B6*5 allele (rs3211371) is variable across different global populations, generally appearing at low to moderate frequencies, often ranging between 1% and 12% depending on the specific ancestry studied.
Frequently asked questions
What does the rs3211371 variant do?
The rs3211371 variant is a genetic change that defines the CYP2B6*5 allele. It is associated with potential changes in the expression or activity of the CYP2B6 enzyme, which is involved in metabolizing various drugs.
Is rs3211371 the same as CYP2B6*6?
No, they are different. While both are variants of the CYP2B6 gene, rs3211371 defines the *5 allele, whereas the *6 allele is a complex haplotype defined by different SNPs, specifically rs2279343 and rs3745274.
Should I change my medication based on my rs3211371 result?
No. You should never change your medication based on a genetic test result without consulting your doctor. Pharmacogenomic results are complex and must be interpreted by a professional in the context of your entire health profile.
How common is the rs3211371 variant?
The frequency of this variant varies significantly by ancestry. Research indicates that its prevalence is generally low, typically appearing in about 1% to 12% of individuals in studied populations.
Sources & further reading
Educational information only, last refreshed 10/5/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Defines the non-functional CYP2B6*18 allele (c.983T>C; p.Ile328Thr) leading to impaired metabolism of efavirenz.
Core coding variant c.1459C>T (p.Arg487Cys) defining CYP2B6*5, associated with reduced clearance of substrates.
Key variant defining the CYP2B6*6 reduced-function allele influencing efavirenz, methadone, and bupropion clearance.
Missense alteration defining the CYP2B6*18 allele, causing profound enzymatic deficiency and impaired clearance of efavirenz and methadone.
A coding variant that defines the decreased-function CYP2B6*4 allele, influencing plasma concentrations of efavirenz, methadone, and bupropion.
Missense alteration defining the nonfunctional CYP2B6*18 allele common in African populations that slows clearance of efavirenz.