SLCO1B1 rs4149057: What Your Genotype Means
The genetic variant rs4149057 (c.388A>G, p.Asn130Asp), commonly referred to in pharmacogenomics alongside rs2306283, is a missense single nucleotide polymorphism in the SLCO1B1 gene. It historically defines the SLCO1B1*1B core haplotype (reclassified by PharmVar as part of SLCO1B1*37) and is involved in the hepatic uptake of endogenous molecules and medications. While associated in some studies with subtle differences in statin clearance, current clinical evidence classifies its isolated standalone impact as normal function or limited relative to higher-risk variants.
What each genotype means
Typical transporter function
This genotype represents the most common form of the SLCO1B1 gene in many populations. Research suggests this version of the transporter typically functions as expected for the uptake of various medications and compounds into the liver. If you are prescribed medications that rely on this transporter, such as certain statins, this genotype is generally considered the baseline for expected drug processing.
This is the most common genotype in many global populations, though frequencies vary significantly by ancestry.
Altered transporter activity
Carrying one copy of the G allele is associated with the *1B suballele, which may influence how efficiently your liver takes up certain medications like statins. Some studies suggest this variant can lead to increased drug response or altered blood levels of specific compounds compared to the AA genotype. Please discuss your medication regimen and any concerns about drug response with your clinician or pharmacist.
This genotype is very common, particularly in populations of African and East Asian ancestry where the G allele is highly prevalent.
Increased transporter activity
This genotype is associated with the *1B suballele, which has been linked in some research to increased hepatic uptake of certain medications. While this may influence how your body processes drugs like atorvastatin, the clinical significance can vary depending on the specific medication and individual health factors. You should consult with your healthcare provider or pharmacist to understand how this might relate to your specific treatment plan.
This genotype is frequently observed in many populations, with high prevalence rates in African and East Asian ancestries.
What Is rs4149057 and Where Is It Located?
The single nucleotide polymorphism rs4149057—often tracked interchangeably in biomedical literature with rs2306283—represents an A-to-G transition at nucleotide 388 (c.388A>G) within the SLCO1B1 gene on human chromosome 12. This missense substitution replaces the amino acid asparagine with aspartic acid at position 130 of the encoded transporter protein (p.Asn130Asp). In traditional pharmacogenetic nomenclature, this variant defined the SLCO1B1*1B haplotype, which modern nomenclature authorities such as the Pharmacogene Variation Consortium (PharmVar) define under the SLCO1B1*37 banner. Because it is an exonic variant directly altering the transporter's amino acid backbone, researchers have extensively studied whether it changes cellular membrane kinetics, though in clinical consensus tables it is classified primarily as maintaining normal transporter activity unless coupled with co-occurring loss-of-function variants.
The Biological Role of the SLCO1B1 Gene
The SLCO1B1 gene encodes the organic anion-transporting polypeptide 1B1 (OATP1B1), an essential membrane influx protein located on the sinusoidal surface of human liver cells. OATP1B1 serves as a molecular gateway, selectively extracting substances from the portal blood circulation into hepatocytes for metabolism, storage, or biliary excretion. Among its key physiological substrates are endogenous bilirubin, bile salts, and thyroid hormones. Pharmacologically, OATP1B1 plays a central role in the hepatic uptake of several widely prescribed drugs, notably statins such as simvastatin, atorvastatin, pravastatin, and rosuvastatin. When OATP1B1 function is altered, drug concentrations in the systemic circulation can shift, altering drug efficacy or the likelihood of systemic side effects.
Clinical Research and Strength of Evidence
Evidence evaluating rs4149057 alone indicates limited independent clinical impact. Unlike the well-characterized rs4149056 (c.521T>C) variant that significantly reduces transport activity and elevates statin-associated muscle symptom risk, rs4149057 (c.388A>G) is recognized by the Clinical Pharmacogenetics Implementation Consortium (CPIC) as defining a normal-function allele (*37/*1B). While some kinetic studies suggest the G allele might slightly enhance uptake or correlate with marginally lower circulating statin concentrations, epidemiological findings across diverse cohorts have yielded mixed results. Most clinical guidelines consider rs4149057 primarily informative in the context of broader haplotype phase determination—such as distinguishing the decreased-function *15 allele (which carries both 388G and 521C) from alleles carrying only one of the variants.
How Common Is rs4149057 Across Populations?
The rs4149057 G allele exhibits notable global frequency differences across biogeographical ancestries. In populations of European descent, the minor allele frequency typically ranges between 35% and 45%, making heterozygosity quite prevalent. Conversely, in East Asian and African populations, the derived G allele is substantially more frequent, often exceeding 70% to 80% allele frequency, making it the major allele in those groups. Because of these pronounced population differences, geneticists emphasize evaluating complete star-allele haplotypes rather than single variants alone, ensuring accurate interpretation of baseline drug-handling capacities across genetically diverse ancestral backgrounds.
What You Can and Cannot Do With This Result
Discovering your rs4149057 genotype provides educational context regarding the natural genetic variation underlying liver transport proteins, but it is not a standalone medical diagnostic. Having one or two copies of the G allele does not diagnose any disease, nor does it guarantee specific responses to statins or other OATP1B1-transported medications. Clinical prescribing algorithms formulated by CPIC evaluate full composite diplotypes—incorporating variants like rs4149056—rather than isolated c.388A>G status. You should never alter, start, or discontinue any prescription medication based on personal genetic results without direct guidance from your treating physician or a licensed clinical pharmacist.
How common is this variant?
The minor allele frequency (G allele) is approximately 35% to 45% in European populations, whereas it represents the major allele with frequencies exceeding 70% to 80% in East Asian and Sub-Saharan African populations.
Frequently asked questions
What is the SLCO1B1 rs4149057 variant?
The rs4149057 variant is a single nucleotide polymorphism in the SLCO1B1 gene that results in a missense amino acid switch (c.388A>G, p.Asn130Asp). It is widely documented in pharmacogenomics as the marker defining the normal-function *1B suballele, now designated *37 by PharmVar.
Does rs4149057 increase my risk for statin muscle pain?
Current evidence suggests rs4149057 alone does not substantially increase the risk of statin-induced myopathy. Strong risk associations are driven primarily by a different variant in the same gene, rs4149056 (c.521T>C), though rs4149057 can be found alongside it on certain haplotypes.
What is the difference between SLCO1B1 *1B and *5?
The *1B allele (defined by c.388A>G) is classified by clinical pharmacogenetic guidelines as a normal-function allele that preserves liver uptake. In contrast, the *5 allele (defined by c.521T>C) significantly impairs transporter activity, leading to higher drug levels in the bloodstream.
Should I stop taking my statin if I have this variant?
No, you should never discontinue or adjust statin medication without speaking to your doctor or pharmacist. The rs4149057 variant does not warrant automatic changes to standard drug therapy on its own.
Sources & further reading
Educational information only, last refreshed 9/8/2026. 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.