SLCO1B1 rs4149056: Statin Response and Muscle Health
The SLCO1B1 rs4149056 variant is a well-studied genetic change that affects how the liver processes certain cholesterol-lowering medications known as statins. Individuals carrying this variant may have a higher risk of experiencing muscle-related side effects when taking specific statin therapies.
What each genotype means
Normal transporter function
This genotype is considered the reference or wild-type profile for this variant. Individuals with this profile typically exhibit normal SLCO1B1 transporter activity, which is responsible for moving statins from the blood into the liver. You should discuss your medication options and any concerns about muscle symptoms with your healthcare provider.
This is the most common genotype observed across most global populations.
Reduced transporter function
This genotype is associated with reduced efficiency in transporting certain statins into the liver, which may lead to higher levels of the medication in your bloodstream. Research suggests this may increase the risk of experiencing statin-associated muscle symptoms. Please consult your clinician or pharmacist to discuss whether your current statin dose or medication choice is appropriate for your genetic profile.
Carried by approximately 15-25% of individuals of European ancestry, though frequencies vary significantly across other global populations.
Significantly reduced transporter function
This genotype indicates a significantly reduced capacity for the SLCO1B1 protein to transport statins into the liver, potentially resulting in higher systemic drug exposure. Clinical guidelines suggest this profile is linked to a higher risk of muscle-related side effects compared to those with the reference genotype. It is important to discuss your specific statin therapy and dosing strategy with your healthcare provider or pharmacist.
This genotype is relatively rare, occurring in a small percentage of the population across most ancestries.
Understanding the rs4149056 Variant
The rs4149056 variant is a single-nucleotide polymorphism (SNP) located within the SLCO1B1 gene. In scientific literature, this specific change is often referred to as c.521T>C, which indicates that a thymine (T) base has been replaced by a cytosine (C) base at a specific position in the DNA sequence. This change results in an amino acid substitution (valine to alanine) in the protein produced by the gene. Because this variant is located in a region that codes for a functional protein, it can alter the protein's activity. Researchers have identified this SNP as a key factor in pharmacogenomics, the study of how genes affect an individual's response to drugs. By analyzing this variant, scientists aim to better understand why some people tolerate statin medications well while others report adverse reactions, such as muscle pain or weakness, even when taking the same dosage.
The Role of the SLCO1B1 Gene
The SLCO1B1 gene provides instructions for making a protein called organic anion transporting polypeptide 1B1 (OATP1B1). This protein acts like a gatekeeper in the liver, responsible for transporting various substances from the blood into liver cells, where they can be processed or cleared from the body. Many medications, including most statins used to lower cholesterol, rely on this transporter to enter the liver effectively. When the SLCO1B1 gene carries the rs4149056 variant, the resulting OATP1B1 protein may function less efficiently. This reduced efficiency can lead to higher levels of statins circulating in the bloodstream rather than being absorbed by the liver. Because the medication remains in the blood at higher concentrations for longer periods, it may reach other tissues, such as muscle, more easily. This increased systemic exposure is believed to be the primary mechanism behind the elevated risk of statin-associated muscle symptoms (SAMS) observed in some patients.
Research and Clinical Evidence
The association between rs4149056 and statin-related myopathy is supported by strong evidence from large-scale clinical studies and meta-analyses. Landmark research, such as the SEARCH trial, demonstrated a clear link between this variant and an increased risk of muscle toxicity, particularly with high-dose simvastatin. Because of these findings, the Clinical Pharmacogenetics Implementation Consortium (CPIC) has developed guidelines to help clinicians manage statin therapy based on a patient's SLCO1B1 genotype. These guidelines suggest that for individuals with decreased or poor transporter function, clinicians might consider alternative statins, lower doses, or closer monitoring for muscle symptoms. It is important to note that while the evidence is strong, genetic status is only one of many factors that influence how a person responds to medication. Other variables, such as age, kidney function, and concurrent use of other drugs, also play significant roles in the development of side effects.
What This Information Means for You
Knowing your genotype for rs4149056 can provide valuable context for your healthcare provider when discussing cholesterol management. However, it is crucial to understand that this information is not a diagnosis and does not predict with certainty whether you will experience side effects. Many people with the variant take statins without any issues, and many people without the variant still experience muscle pain. If you have concerns about your medication, you should never stop or change your treatment plan without consulting your doctor or pharmacist. They are the best resources to interpret your genetic information in the context of your overall health, medical history, and current treatment goals. They can help determine if a dose adjustment or a different medication is appropriate for your specific situation, ensuring that you continue to manage your cholesterol safely and effectively.
How common is this variant?
The rs4149056 variant is common, with approximately 15-25% of individuals of European ancestry carrying at least one copy of the C allele. Frequencies can vary significantly across different global populations.
Frequently asked questions
Does having the rs4149056 variant mean I cannot take statins?
No, having this 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 ensure it is both effective and well-tolerated.
What are the symptoms of statin-related myopathy?
Statin-related myopathy typically presents as muscle pain, soreness, or weakness. In rare cases, it can involve more severe muscle damage, which is why monitoring is important.
Should I get a genetic test for SLCO1B1?
Genetic testing for SLCO1B1 is not routinely required for everyone. You should discuss with your doctor whether such testing is relevant to your specific medical situation or history of medication side effects.
Can I change my SLCO1B1 genotype?
No, your genotype is determined by your DNA and cannot be changed. However, knowing your genotype allows your healthcare team to personalize your treatment plan to work with your body's unique biology.
Sources & further reading
Educational information only, last refreshed 9/30/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This missense variant (p.Pro155Thr) is associated with reduced OATP1B1 transporter function, which can lead to increased plasma concentrations of certain statins and higher risk of myopathy.
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.