SLCO1B1 rs4149056: Statin Response and Muscle Health
The SLCO1B1 rs4149056 variant is a genetic change in the SLCO1B1 gene that affects how the liver processes certain medications. It is primarily studied for its association with an increased risk of muscle pain, known as myopathy, in patients taking statins.
What each genotype means
Typical transporter function
You carry two copies of the reference C allele for this variant in SLCO1B1. This genotype is associated with normal baseline hepatic uptake activity for substrate drugs, meaning typical transport of statins and methotrexate relative to this site. If you are taking or considering statin therapy, your healthcare provider or pharmacist will evaluate your overall clinical and genetic profile to determine standard medication management.
Carried by approximately 96% to 98% of individuals across European, East Asian, and global populations.
Altered transporter activity
You carry one copy of the A missense allele (defining the p.Pro155Thr change seen in the *14 and *37 star alleles). Published research indicates this change may cause altered hepatic clearance and systemic levels of substrates such as statins and methotrexate, though clinical evidence regarding its overall health outcome impact remains limited. Discuss any questions about drug selection or dosing with your clinician or pharmacist.
Carried by roughly 1% to 3% of individuals in European and East Asian cohorts, and is uncommon globally.
Significantly altered transporter function
You carry two copies of the A missense allele for this SLCO1B1 variant. Research suggests this genotype may noticeably alter OATP1B1-mediated hepatic transport of certain medications, which could influence blood concentrations of statins or methotrexate; however, published outcome data specifically evaluating homozygotes remain very limited. It is essential to discuss your medication regimens, dosing, and potential side effect monitoring with your physician or pharmacist.
Extremely rare across all studied populations, occurring in fewer than 1 in 1,000 individuals.
Understanding the Variant
The rs4149056 variant is a single nucleotide polymorphism (SNP) located within the SLCO1B1 gene. In genetic literature, this variant is often referred to as the c.521T>C polymorphism. It involves a change in the DNA sequence where a thymine (T) is replaced by a cytosine (C). This specific change is considered a missense mutation, meaning it alters the genetic code in a way that changes the amino acid sequence of the resulting protein. Because this variant sits in a critical region of the gene, it can influence the structure and efficiency of the protein it encodes. Researchers track this SNP because it serves as a marker for how an individual's body might handle specific drugs that rely on this protein for transport into the liver, where they are processed and cleared from the bloodstream.
The Role of the SLCO1B1 Gene
The SLCO1B1 gene provides instructions for making a protein called organic anion-transporting polypeptide 1B1, or OATP1B1. This protein acts like a gatekeeper in the liver, responsible for transporting various substances—including bile acids, hormones, and many medications—from the blood into liver cells. Statins, a common class of drugs used to lower cholesterol, are primary substrates for this transporter. When OATP1B1 is functioning normally, it efficiently moves statins into the liver. However, when the function of this transporter is reduced, the medication may not be cleared from the blood as quickly as expected. This leads to higher concentrations of the drug circulating in the body, which can increase the risk of side effects, particularly in muscle tissue, as the drug remains in the system longer than intended.
Research and Clinical Associations
Extensive research, including large-scale genome-wide association studies, has linked the C allele of rs4149056 to an increased risk of statin-induced myopathy. Studies have shown that individuals carrying one or two copies of the C allele may experience higher plasma concentrations of statins, such as simvastatin or atorvastatin, compared to those with the TT genotype. The evidence for this association is considered strong, particularly for simvastatin. While the risk is statistically significant, it is important to note that not everyone with the C allele will experience muscle symptoms. The clinical impact can vary based on the specific type of statin, the dosage prescribed, and other individual health factors. Because of these findings, some clinical guidelines suggest that healthcare providers consider this genetic information when determining the appropriate statin therapy for a patient.
Population Frequency
The frequency of the rs4149056 variant varies significantly across different global populations. The C allele is found at different rates depending on ancestry, which influences the prevalence of this pharmacogenetic trait in various regions. Because of this variability, the clinical relevance of testing for this variant can differ depending on the patient's background. It is a well-documented marker in pharmacogenomic screening programs, where it is used to help clinicians tailor medication plans to reduce the likelihood of adverse drug reactions.
What This Information Means for You
Knowing your genotype for rs4149056 provides insight into how your body might process certain statins, but it is not a diagnostic tool for muscle disease. Having a specific genotype does not guarantee that you will experience side effects, nor does it mean you cannot take statins safely. Many people with the C allele take statins without any issues, often by adjusting the dose or switching to a different type of statin. This information should be used as a tool for conversation with your healthcare provider or pharmacist. They can interpret these results in the context of your overall health, current medications, and cholesterol management goals. Never make changes to your prescribed medication regimen based on genetic test results without first consulting a medical professional who can provide personalized guidance.
How common is this variant?
The frequency of the C allele varies by ancestry, with significant differences observed between global populations. It is a clinically relevant marker often included in pharmacogenomic screening panels.
Frequently asked questions
Does having the SLCO1B1 variant mean I cannot take statins?
No, having the variant does not mean you cannot take statins. It simply means your doctor may need to consider your genotype when choosing the type or dose of statin to minimize the risk of muscle-related side effects.
What are the symptoms of statin-induced myopathy?
Statin-induced myopathy typically presents as muscle pain, tenderness, or weakness. If you are taking a statin and experience unexplained muscle symptoms, you should contact your healthcare provider immediately.
Is a genetic test for SLCO1B1 required before starting a statin?
Routine genetic testing for SLCO1B1 is not universally required for all patients starting statins. However, it may be considered in specific clinical situations or if a patient has a history of statin intolerance.
Can I change my SLCO1B1 genotype?
No, your genotype is determined at birth and cannot be changed. It is a permanent part of your genetic makeup.
Sources & further reading
Educational information only, last refreshed 10/17/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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A regulatory variant in the SLCO1B1 gene influencing statin pharmacokinetics.
Defines the c.388A>G (p.Asn130Asp) variant, which is a component of the SLCO1B1*1B and *15 haplotypes, influencing hepatic statin uptake.
Non-synonymous coding polymorphism (p.Asn130Asp) defining the SLCO1B1*30 allele with modest alteration in hepatic statin uptake.
This variant (c.521T>C) is strongly associated with decreased function of the OATP1B1 transporter, significantly increasing the risk of statin-induced myopathy.
Known as SLCO1B1*1b (p.Asn130Asp), this variant alters hepatic transporter activity and modulates statin exposure and pharmacokinetic clearance.
Defines the SLCO1B1*14 haplotype (p.Gly488Ala) associated with altered hepatic uptake transporter activity and statin pharmacokinetics.