CYP2D6 rs11572080: Understanding the *41 Reduced-Function Allele
The rs11572080 variant is a specific genetic marker used to identify the CYP2D6*41 allele, which is associated with reduced enzyme activity. This genetic variation can influence how an individual metabolizes various clinical medications, potentially leading to intermediate metabolizer status.
What each genotype means
Normal enzyme activity
This genotype indicates you carry two copies of the reference allele, which is associated with normal CYP2D6 enzyme function. You are likely to metabolize medications processed by this enzyme at a standard rate. Please discuss any medication dosing or concerns with your clinician or pharmacist.
This is the most common genotype in most global populations, though frequency varies significantly by ancestry.
Reduced enzyme activity
This genotype includes one copy of the reduced-function allele associated with the CYP2D6*41 haplotype. You may be classified as an intermediate metabolizer, which can influence how your body processes certain drugs like tamoxifen or codeine. Please consult your healthcare provider or pharmacist to determine if this impacts your specific medication therapy.
The A allele is carried by approximately 8-10% of individuals of European ancestry and is less common in East Asian populations.
Reduced enzyme activity
This genotype indicates you carry two copies of the reduced-function allele associated with the CYP2D6*41 haplotype. This status is often linked to an intermediate metabolizer phenotype, which may lead to altered drug levels for certain medications. Always discuss your genetic results and medication management with your clinician or pharmacist.
This homozygous genotype is relatively rare, occurring in approximately 1% or less of European populations based on typical allele frequencies.
What is the rs11572080 Variant?
The rs11572080 variant is a single nucleotide polymorphism (SNP) located within the CYP2D6 gene. In the context of pharmacogenomics, this specific change (2988G>A) serves as a defining marker for the CYP2D6*41 allele. The CYP2D6 gene is highly polymorphic, meaning it contains many variations that can alter the function of the protein it encodes. When researchers identify the presence of the 'A' allele at this position, they categorize it as part of the *41 haplotype. This allele is clinically significant because it is classified as a reduced-function variant, meaning the enzyme produced by the gene works less efficiently than the standard, fully functional version. Understanding this variant is a key component of pharmacogenetic testing, which aims to predict how a person's unique genetic makeup might affect their response to specific drugs.
The Role of the CYP2D6 Gene
The CYP2D6 gene provides instructions for making an enzyme called cytochrome P450 2D6. This enzyme is primarily found in the liver and is responsible for metabolizing, or breaking down, approximately 25% of all clinically prescribed medications. By converting these drugs into active or inactive forms, the enzyme plays a critical role in determining the concentration of medication in the bloodstream. Because the gene is so diverse, individuals can be categorized into different metabolizer phenotypes: poor, intermediate, normal, or ultrarapid. Those with the *41 allele, which is identified by the rs11572080 variant, often fall into the intermediate metabolizer category. This means their ability to process certain drugs, such as codeine or tamoxifen, may be slower than average, which can impact the drug's efficacy or the risk of side effects.
Research and Clinical Evidence
Research into the CYP2D6*41 allele is ongoing, and the evidence regarding its clinical impact is considered limited in some contexts. While it is well-established that the *41 allele results in reduced enzyme activity, the clinical consequences vary depending on the specific medication being used. For example, in the case of tamoxifen, which requires conversion to its active metabolite endoxifen, reduced enzyme activity may lead to lower drug levels and potentially reduced therapeutic benefit. However, clinical guidelines, such as those from the National Comprehensive Cancer Network, do not currently recommend routine CYP2D6 testing to guide all treatment strategies. It is important to note that pharmacogenetic associations are complex and often involve multiple genes and environmental factors. Because the evidence strength is categorized as limited for many applications, clinicians must weigh genetic findings alongside other clinical data when making treatment decisions.
Population Frequency
The frequency of the CYP2D6*41 allele varies significantly across different ancestral populations. In European populations, the allele is relatively common, with frequencies typically reported between 8% and 11%. In contrast, the allele is less common in East Asian populations, where it is found at a frequency of approximately 2% to 4%. These differences highlight the importance of considering ancestry when interpreting genetic test results. Because the prevalence of specific alleles changes based on geographic and ethnic background, a result that is common in one population may be rare in another. Researchers continue to study these frequency distributions to better understand the global landscape of pharmacogenetic variation and to improve the accuracy of personalized medicine approaches across diverse groups.
What You Can Do With This Information
If you have received information about your CYP2D6 genotype, it is essential to understand that this data is only one piece of a much larger clinical puzzle. Genetic variants do not act in isolation; your overall health, other medications you may be taking, and your lifestyle also influence how your body processes drugs. You should never use genetic information to make changes to your prescribed medications or dosages on your own. Instead, use this information as a starting point for a conversation with your healthcare provider or a clinical pharmacist. They are trained to interpret these results in the context of your specific medical history and can determine if a medication adjustment is necessary or if an alternative treatment would be more appropriate for your needs. Always prioritize professional medical advice over direct-to-consumer genetic reports.
How common is this variant?
The CYP2D6*41 allele frequency is approximately 0.08-0.11 in European populations and roughly 0.02-0.04 in East Asian populations.
Frequently asked questions
Does having the *41 allele mean I cannot take certain medications?
Not necessarily. Having the *41 allele may mean your body processes certain drugs more slowly, but it does not mean you cannot take them. Your doctor may simply adjust the dose or choose an alternative medication based on your specific needs.
Is a CYP2D6 test required before starting medication?
Routine testing is not required for all medications. Clinical guidelines vary by drug, and many healthcare providers only consider testing if there is a specific clinical concern regarding drug efficacy or side effects.
Can I change my medication dose based on my genotype?
No. You should never change your medication dosage or stop taking a prescribed drug based on genetic test results without consulting your physician or pharmacist first.
Why does the frequency of this variant differ by ancestry?
Genetic variation is influenced by human migration and evolutionary history. Over thousands of years, different populations have developed different frequencies of specific genetic markers, including those in the CYP2D6 gene.
Sources & further reading
Educational information only, last refreshed 9/21/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This variant is a key marker for the CYP2D6*10 allele, which results in reduced enzymatic activity and altered metabolism of various psychiatric and analgesic medications.
This variant defines the CYP2D6*4 non-functional allele, which causes impaired metabolism of numerous clinically prescribed medications including antidepressants, tamoxifen, and codeine.
Defines the CYP2D6*17 allele (p.Thr107Ile), which exhibits reduced enzyme activity towards substrates like codeine and certain antidepressants.
Defines the CYP2D6*29 variant (p.Val338Met) conferring decreased metabolic capacity, primarily observed in populations of African descent.
Promoter variant defining the CYP2D6*41 allele, associated with reduced enzyme expression and decreased metabolic capacity for various drugs.
Defines the non-functional CYP2D6*41 splice defect associated with intermediate metabolizer phenotype affecting codeine, tamoxifen, and SSRI metabolism.