CYP2C19 rs72558190: What Your Genotype Means
The rs72558190 variant is a specific genetic change located within the CYP2C19 gene. It is recognized as a nonfunctional allele that may impair the body's ability to activate the antiplatelet medication clopidogrel.
What each genotype means
Normal enzyme activity
This genotype represents the most common form of the CYP2C19 gene, often referred to as the *1/*1 diplotype. Individuals with this profile typically have normal enzyme function and are expected to process clopidogrel as intended. Please discuss any medication-related concerns or dosing strategies with your clinician or pharmacist.
This is the most common genotype found across all global populations.
Reduced enzyme activity
This genotype indicates you carry one copy of the *4 loss-of-function allele, which is associated with reduced CYP2C19 enzyme activity. Research suggests that individuals with reduced function may have a diminished response to clopidogrel, potentially increasing the risk of cardiovascular events. Please consult your healthcare provider or pharmacist to discuss whether this impacts your current treatment plan.
This genotype is rare, with the *4 allele occurring at a frequency of less than 0.005 across most ancestries.
Impaired enzyme activity
This genotype indicates you carry two copies of the *4 loss-of-function allele, which significantly impairs the activity of the CYP2C19 enzyme. Because this enzyme is required to activate clopidogrel, this profile is associated with a higher risk of reduced drug effectiveness and potential adverse cardiovascular outcomes. It is important to discuss these findings with your clinician or pharmacist to determine if alternative antiplatelet therapies are appropriate for you.
This genotype is extremely rare in the general population.
Understanding the rs72558190 Variant
The rs72558190 variant is a single nucleotide polymorphism (SNP) found within the CYP2C19 gene, which provides instructions for making an enzyme essential for drug metabolism. In the context of pharmacogenomics, this specific variant is categorized as a nonsynonymous missense mutation. This means the change in the DNA sequence results in an alteration of the protein structure, which can impact the enzyme's functional capacity. This variant is specifically associated with the CYP2C19*4 allele, a known nonfunctional allele. Because the CYP2C19 enzyme is responsible for converting certain medications from their inactive prodrug form into their active, therapeutic form, variations that disrupt this process can lead to differences in how an individual responds to specific treatments.
The Role of the CYP2C19 Gene
The CYP2C19 gene belongs to the cytochrome P450 family, a group of enzymes primarily located in the liver that are responsible for metabolizing a wide range of substances, including many prescription drugs. For patients prescribed clopidogrel, a common antiplatelet medication used to prevent blood clots, the CYP2C19 enzyme is critical. Clopidogrel is a prodrug, meaning it must be processed by the liver to become active. When the CYP2C19 enzyme is not functioning optimally due to genetic variants like rs72558190, the conversion of clopidogrel into its active metabolite is significantly reduced. This can lead to lower levels of the active drug in the bloodstream, potentially decreasing the medication's effectiveness in preventing cardiovascular events such as stent thrombosis or stroke.
Research and Clinical Evidence
Research into CYP2C19 variants has established a clear link between loss-of-function alleles and reduced clopidogrel responsiveness. While the evidence for the specific impact of rs72558190 is considered limited compared to more common variants like *2 or *3, it is classified as a nonfunctional allele. Clinical guidelines, such as those from the Clinical Pharmacogenetics Implementation Consortium (CPIC), emphasize that patients carrying loss-of-function alleles may not achieve the expected therapeutic benefit from standard clopidogrel dosing. It is important to note that while genetic associations are strong, individual responses to medication are complex and influenced by other factors, including drug-drug interactions, diet, and overall health. Always consult with a healthcare provider or pharmacist to interpret how your specific genetic profile might influence your treatment plan.
Population Frequency and Interpretation
The rs72558190 variant is considered rare, with a minor allele frequency typically reported as less than 0.005 across most global populations. Because it is uncommon, most individuals will not carry this specific variant. When interpreting genetic data, it is essential to remember that having a variant does not automatically mean a medication will be ineffective, nor does the absence of a variant guarantee a perfect response. Genetic testing provides one piece of information that clinicians use alongside clinical history and other diagnostic tests to personalize medical care. If you have received results indicating you carry this variant, do not make any changes to your prescribed medications. Instead, use this information to facilitate a conversation with your doctor about whether alternative therapies or dosage adjustments are appropriate for your specific clinical situation.
How common is this variant?
The rs72558190 variant is rare, with a minor allele frequency of less than 0.005 across most ancestral populations.
Frequently asked questions
What does it mean to be a poor metabolizer of clopidogrel?
Being a poor metabolizer means your body does not efficiently convert clopidogrel into its active form. This can result in the medication being less effective at preventing blood clots.
Should I stop taking my medication if I have this variant?
No, you should never stop or change your medication without consulting your doctor. Genetic variants are only one factor in how your body responds to drugs, and your physician must weigh all clinical information before making changes.
Is rs72558190 the same as the CYP2C19*4 allele?
Yes, rs72558190 is a genetic marker characteristic of the CYP2C19*4 nonfunctional allele. It is often used in testing to identify this specific loss-of-function variant.
How can I find out if I have this variant?
This variant is typically identified through pharmacogenetic testing, which is often ordered by a cardiologist or primary care physician. You can discuss the necessity of such testing with your healthcare provider.
Sources & further reading
Educational information only, last refreshed 9/17/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Defines the CYP2C19*17 increased function allele, conferring rapid or ultrarapid metabolism for CPIC-actionable drugs including clopidogrel, PPIs, and SSRIs.
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.