CYP2C19 rs12248560: What Your Genotype Means
The rs12248560 variant is a genetic change in the CYP2C19 gene that defines the *17 allele. This variant is associated with increased enzyme activity, which can lead to faster metabolism of specific medications like clopidogrel, proton pump inhibitors, and certain antidepressants.
What each genotype means
Normal enzyme activity
This genotype represents the absence of the CYP2C19*17 gain-of-function variant. Individuals with this profile typically exhibit standard metabolism for drugs processed by the CYP2C19 enzyme, such as clopidogrel, certain antidepressants, and proton pump inhibitors. Please discuss your medication dosing and potential treatment responses with your clinician or pharmacist.
This is the most common genotype in most global populations, though frequency varies significantly by ancestry.
Increased enzyme activity
Carrying one copy of the T allele (often referred to as the *17 allele) is associated with increased transcription of the CYP2C19 gene. This may lead to faster metabolism of certain medications, which can influence their clinical effectiveness or required dosage. Please consult with your healthcare provider or pharmacist regarding how this genetic profile might affect your specific medication therapy.
This heterozygous genotype is found in approximately 15-25% of individuals of European and African ancestries, and is less common in East Asian populations.
Ultrarapid enzyme activity
Carrying two copies of the T allele (the *17/*17 genotype) is associated with an ultrarapid metabolizer phenotype. This can result in increased clearance and decreased half-life of drugs metabolized by CYP2C19, potentially impacting the therapeutic efficacy of medications like clopidogrel or SSRIs. Always discuss your medication management and any concerns about drug response with your clinician or pharmacist.
This homozygous genotype is less common than the heterozygous form, appearing in a smaller subset of European and African populations and rarely in East Asian populations.
What is the rs12248560 Variant?
The rs12248560 variant is a single nucleotide polymorphism (SNP) located in the promoter region of the CYP2C19 gene. Specifically, it involves a C to T transition at position -806. This change is significant because it creates a new binding site for the GATA family of transcription factors. By altering this regulatory region, the variant increases the transcription of the CYP2C19 gene, leading to higher levels of the CYP2C19 enzyme in the body. In the nomenclature of pharmacogenetics, this specific genetic change is the defining marker for the CYP2C19*17 allele. While many variants in this gene are associated with reduced or absent enzyme function, rs12248560 is categorized as a gain-of-function variant, meaning it enhances the body's ability to process substances that are normally broken down by this enzyme.
The Role of the CYP2C19 Gene
The CYP2C19 gene provides instructions for making an enzyme that belongs to the cytochrome P450 family. These enzymes are primarily found in the liver and are responsible for metabolizing a wide variety of substances, including many prescription medications. By breaking down these drugs, the CYP2C19 enzyme helps the body clear them from the system. Because individuals have different genetic versions of this gene, the speed at which they metabolize these drugs can vary significantly. Some people have 'normal' function, while others may have 'reduced' or 'no' function, leading to slower drug clearance. Conversely, individuals with the *17 allele, defined by rs12248560, have 'increased' function. This means they may clear certain medications from their bloodstream more rapidly than the average person, which can potentially impact the effectiveness of the treatment.
Research and Clinical Associations
Research into rs12248560 has focused on how the *17 allele affects the clinical response to drugs such as clopidogrel, proton pump inhibitors (PPIs), and certain antidepressants. Because the *17 allele leads to faster metabolism, there is a theoretical risk that patients might clear these drugs too quickly, potentially reducing their therapeutic effect. However, the evidence regarding clinical outcomes is mixed. While some studies suggest that *17 carriers might require different dosing strategies to achieve optimal drug levels, other research has not consistently demonstrated significant differences in clinical outcomes. Because the evidence is considered limited or context-dependent, it is essential that patients do not make changes to their medication based on this information alone. Always discuss your genetic results and any concerns about medication efficacy with your healthcare provider or a clinical pharmacist who can interpret these findings in the context of your overall health.
Population Frequency
The frequency of the rs12248560 variant varies significantly across different ancestral groups. It is most common in European, African, and Near Eastern populations, where the allele frequency is approximately 15% to 25%. In contrast, the variant is much less common in East Asian populations, where it is typically found at a frequency of about 2% or lower. These differences highlight the importance of considering ancestry when evaluating the potential impact of pharmacogenetic variants. Because the prevalence of the *17 allele is not uniform globally, the likelihood of an individual carrying this variant depends heavily on their genetic background.
What You Can and Cannot Do
Understanding your genotype for rs12248560 can be a useful piece of information for your medical team, but it is not a diagnostic tool on its own. You cannot use this information to diagnose a condition or to determine if a medication is 'right' or 'wrong' for you without professional guidance. Pharmacogenomics is a complex field where genetics is only one of many factors—such as age, weight, diet, and other medications—that influence how your body responds to drugs. If you have received genetic testing results indicating you carry the *17 allele, you should share this report with your doctor or pharmacist. They are the only ones qualified to determine if your specific genotype warrants a change in your medication or dosage. Never stop or change your prescribed treatment based on your own interpretation of genetic data.
How common is this variant?
The rs12248560 variant is common in European and African ancestries with an allele frequency of approximately 15-25%, while it is significantly less common in East Asian populations at about 2%.
Frequently asked questions
What does it mean to be a CYP2C19 rapid metabolizer?
Being a rapid metabolizer means your body processes certain medications faster than average due to increased activity of the CYP2C19 enzyme. This can sometimes result in lower levels of the drug in your blood, potentially reducing its effectiveness.
Does having the *17 allele mean my medication won't work?
Not necessarily. While the *17 allele increases enzyme activity, many factors influence how well a drug works. You should consult your doctor to see if your specific medication is affected by this variant.
Should I get tested for CYP2C19 variants?
Genetic testing for pharmacogenomics is typically recommended by a healthcare provider if you are starting a medication known to be affected by CYP2C19. Discuss the necessity of such testing with your physician.
Is rs12248560 the same as CYP2C19*17?
Yes, rs12248560 is the specific genetic marker (SNP) used to identify the CYP2C19*17 allele. The *17 notation is the standard way scientists and clinicians refer to this specific functional variant.
Sources & further reading
Educational information only, last refreshed 10/26/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Get my report — $29Related variants in CYP2C19
The CYP2C19*2 loss-of-function splicing defect results in impaired biotransformation of prodrugs including clopidogrel and altered clearance of proton pump inhibitors and select antidepressants.
Variant in the CYP2C19 locus associated with altered metabolism of clopidogrel and proton-pump inhibitors.
Defines the CYP2C19*8 loss-of-function variant (c.358T>C, p.Trp120Arg) which results in no enzymatic activity and impaired metabolism of CYP2C19 substrates.
Defines the non-functional CYP2C19*3 null allele resulting from a premature stop codon, leading to poor metabolism of drugs such as clopidogrel, escitalopram, and proton pump inhibitors.
Defines the CYP2C19*4 allele caused by an ATG start codon alteration that abolishes translation, resulting in reduced or absent drug metabolism capacity.
Known as CYP2C19*3, this premature stop codon (c.636G>A, p.Trp212Ter) results in a complete loss-of-function phenotype for clopidogrel and antidepressant metabolism.