CYP2D6 rs1058164: Understanding Your Pharmacogenetic Profile
The rs1058164 variant is a genetic marker located within the CYP2D6 gene, which plays a critical role in how the body processes many common medications. It is frequently used as a diagnostic indicator for the CYP2D6*10 allele, which is associated with reduced enzyme activity and altered drug metabolism.
What each genotype means
Typical CYP2D6 enzyme activity
You carry two copies of the reference C allele at rs1058164. In populations studied in pharmacogenomics research, this genotype is typically associated with standard baseline CYP2D6 expression and normal drug clearance when no other altered alleles are present. Because overall drug metabolism depends on full CYP2D6 haplotype testing and potential gene duplications, always consult your physician or pharmacist before altering any medication dosages.
Carried by approximately 40% to 60% of individuals in European and African populations, but less common in East Asian populations where the variant G allele predominates.
Intermediate CYP2D6 activity risk
You carry one copy of the G allele at rs1058164, which is commonly found on CYP2D6 star-allele haplotypes associated with reduced enzyme activity and alternative splicing. Studies suggest that individuals carrying this variant may exhibit slower clearance or altered activation of medications metabolized by CYP2D6, including select antidepressants, antipsychotics, and pain medications. If you take or plan to start any CYP2D6-metabolized drugs, discuss your personalized pharmacogenomic profile with your healthcare provider or pharmacist.
Carried by approximately 40% to 50% of individuals in East Asian populations, and around 15% to 30% of individuals in European and African ancestries.
Reduced CYP2D6 enzyme activity
You carry two copies of the G allele at rs1058164, a genotype frequently linked to reduced-function alleles such as CYP2D6*10. Published research indicates that individuals with this profile often have significantly lower CYP2D6 clearance, potentially leading to increased blood levels of certain medications or reduced activation of specific prodrugs like codeine. Because dosing requirements can differ markedly, discuss these findings with your clinician or clinical pharmacist before making any medication changes.
Found in approximately 25% to 40% of East Asian populations, but rare in individuals of European and African ancestries (often under 5%).
What is rs1058164 and Where is it Located?
The rs1058164 variant is a single nucleotide polymorphism (SNP) found within the CYP2D6 gene on chromosome 22. In genetic databases, this variant is often described as a G to C substitution. It serves as a vital landmark for researchers and clinicians because it is a defining component of the CYP2D6*10 haplotype. Because this SNP is located within the coding region of the gene, it can influence the structure and function of the resulting protein. Geneticists track this specific position to help categorize individuals into different metabolizer groups, which can be essential for understanding how a person might respond to various therapeutic drugs. It is not a standalone indicator of health, but rather one piece of a complex genetic puzzle that determines how efficiently your liver enzymes break down substances.
The Role of the CYP2D6 Gene
The CYP2D6 gene provides instructions for making an enzyme that is part of the cytochrome P450 family. This enzyme is responsible for metabolizing approximately 25% of all clinically used drugs, including antidepressants, antipsychotics, and certain pain medications. When the CYP2D6 gene functions normally, the body processes these medications at a predictable rate. However, variations like rs1058164 can lead to reduced enzyme activity. When enzyme activity is lower than average, medications may remain in the bloodstream for longer periods, potentially increasing the risk of side effects or requiring dosage adjustments. Conversely, if the enzyme is highly active, some drugs might be cleared too quickly to be effective. Understanding your specific CYP2D6 profile is a cornerstone of pharmacogenomics, the study of how genes affect a person's response to drugs.
Research Associations and Evidence Strength
Research has consistently linked the presence of the rs1058164 variant to the CYP2D6*10 allele, which is classified as a reduced-function allele. Studies have shown that individuals carrying this variant may experience altered plasma concentrations of medications such as risperidone, an antipsychotic drug. While the association between this variant and reduced metabolic capacity is well-documented in scientific literature, the clinical impact can vary significantly between individuals. The evidence strength for this variant as a marker for drug response is considered robust in the context of pharmacogenomics, but it is important to note that other genetic and environmental factors also influence drug metabolism. Because of this complexity, genetic testing results should always be interpreted by a qualified healthcare professional who can consider your entire clinical picture, including other medications you may be taking.
Population Frequency and Distribution
The frequency of the rs1058164 variant varies significantly across different ancestral populations. It is notably common in East Asian populations, where the associated CYP2D6*10 allele is frequently observed, sometimes reaching frequencies as high as 40% to 60%. In contrast, this variant is much less common in European and certain other populations. These differences highlight the importance of considering ancestry in pharmacogenomic research and clinical practice. Because the prevalence of this variant is so high in specific groups, it is a primary focus for researchers studying drug response variability in those populations. Understanding these global patterns helps scientists develop more inclusive and accurate guidelines for personalized medicine, ensuring that drug dosing recommendations are relevant to diverse patient groups worldwide.
What You Can and Cannot Do With This Information
If you have information about your rs1058164 genotype, it is important to use it as a tool for conversation rather than a basis for self-diagnosis. You cannot use this information to determine your own medication dosages or to decide whether to stop taking a prescribed treatment. Pharmacogenomics is a complex field, and your genetic result is only one factor that a doctor considers when prescribing medication. You should share any genetic reports with your clinician or pharmacist, as they are trained to integrate this data with your medical history, current symptoms, and other health factors. They can help you understand if your genotype suggests a need for a different medication or a dosage adjustment. Always consult with your healthcare provider before making any changes to your treatment plan, as they are the only ones who can safely manage your care.
How common is this variant?
The rs1058164 variant is highly prevalent in East Asian populations, where the associated CYP2D6*10 allele is common, while it appears at significantly lower frequencies in European and African populations.
Frequently asked questions
Does having the rs1058164 variant mean I will have bad side effects from medication?
Not necessarily. While this variant is associated with reduced enzyme activity, many factors influence how you respond to a drug, including your age, diet, and other medications. A genetic result is just one piece of information your doctor uses to manage your treatment.
Should I get tested for CYP2D6 variants?
Genetic testing for pharmacogenes is usually recommended by a doctor if you are having trouble finding an effective medication or are experiencing unexpected side effects. You should discuss the necessity of such testing with your healthcare provider.
Can I change my CYP2D6 genotype?
No, your genotype is determined at birth and cannot be changed. However, knowing your genotype can help your doctor choose medications that are better suited to your body's natural metabolic profile.
Is rs1058164 the only variant that affects CYP2D6?
No, the CYP2D6 gene is highly polymorphic, meaning there are many different variants that can affect its function. Clinicians often look at a panel of variants to get a complete picture of your metabolic status.
Sources & further reading
Educational information only, last refreshed 10/27/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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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 CYP2D6*6 deletion variant (1707delT) leading to a premature stop codon and loss of enzyme function.
Defines the non-functional CYP2D6*41 splice defect associated with intermediate metabolizer phenotype affecting codeine, tamoxifen, and SSRI metabolism.