What you carry at this position in your DNA and what research says about it.
Statin Muscle Toxicity: 5/10 evidence, 16 publications.
You're viewing every possible genotype for this variant.
None of these is your result. Use the genotype toggle to compare them, then sign up and upload your DNA to see which one is yours.
Sample genotype (not yours): T/T
Typical Risk of Statin-Induced Muscle Pain
Normal transporter function ensures that cholesterol-lowering statin medications are cleared from the bloodstream at a typical rate. This significantly minimizes the risk of developing statin-induced muscle pain or weakness.
What this genotype means: Typical statin clearance; Baseline risk of muscle pain.
Sample genotype (not yours): C/C
Highly Elevated Risk of Statin Muscle Pain
Carrying two copies of the C allele severely limits liver transporter activity, causing statin medications to build up in the blood. This significantly increases the risk of muscle pain and weakness by up to 17-fold.
What this genotype means: Severely reduced statin clearance; Highly elevated risk of muscle pain.
Sample genotype (not yours): T/C
Moderately Increased Risk of Statin Muscle Pain
Carrying one copy of the C allele moderately reduces liver transporter activity, leading to slower clearance of certain statin medications. This results in higher drug levels in the blood and a roughly 4.5-fold higher risk of muscle pain.
What this genotype means: Slower statin clearance; Increased risk of muscle pain.
Gene function and biological role
Gene Function: The SLCO1B1 gene encodes a critical transport protein called organic anion-transporting polypeptide 1B1, or OATP1B1 [1]. This transporter is located on the surface of liver cells, where it acts as a gateway to pull compounds from the bloodstream into the liver [1]. It is responsible for clearing various substances, including natural waste products like bilirubin and widely prescribed cholesterol-lowering medications known as statins [1] [2]. When the transporter is functioning normally, it helps maintain healthy blood levels of these compounds by facilitating their processing and elimination [1]. Variations in this gene can significantly alter how efficiently the transporter works, directly affecting drug safety and metabolic traits [2].
Variant Impact: The rs4363657 variant is an intronic change located within the SLCO1B1 gene that serves as a strong genetic marker for transporter activity [1]. It is in almost perfect linkage disequilibrium with the functional missense variant rs4149056, meaning they are almost always inherited together [1]. The presence of the C allele at this position is strongly linked to reduced transporter function, which slows down the rate at which the liver can absorb statins from the blood [1] [3]. This reduction in uptake leads to higher circulating levels of statins in the bloodstream, increasing the risk of muscle-related side effects [1] [2]. Conversely, the T allele represents the fully functional, typical version of the transporter [1].
Key Insight: This genetic variant is one of the most well-established markers in pharmacogenomics, directly influencing how safely a person can take common cholesterol-lowering medications.
Location: SLCO1B1. Chromosome 12 · 12p12.1 · 21.2 Mb
Estimated prevalence by population
Global 67.3%; European 68.7%; African 72.7%; East Asian 30.3%; South Asian 83.1%; Americas 67.6%; Ashkenazi 68.6%; Finnish 46.0%; Middle Eastern 65.0%; Amish 86.9%.
Estimated TT genotype frequency.
Global 28.9%; European 28.3%; African 25.1%; East Asian 49.5%; South Asian 16.1%; Americas 29.3%; Ashkenazi 28.4%; Finnish 43.6%; Middle Eastern 31.3%; Amish 12.7%.
Estimated TC genotype frequency.
Global 3.8%; European 2.9%; African 2.2%; East Asian 20.2%; South Asian 0.8%; Americas 3.2%; Ashkenazi 2.9%; Finnish 10.3%; Middle Eastern 3.8%; Amish 0.5%.
Estimated CC genotype frequency.
Showing effects for T/T genotype
Pharmacogenomics
Adverse Drug Reactions
Statin Muscle Pain. Evidence: 5/10. Source: PMID 18650507. Typical Risk.
Lipid-Lowering Drug Response
Atorvastatin Clearance. Evidence: 4/10. Source: PMID 38493369. Typical Clearance.
Organ Systems
Liver Function & Disease
Bilirubin Levels. Evidence: 4/10. Source: PMID 21646302. Typical Levels.
Cardiovascular & Metabolic
Blood Cell & Iron Traits
Monocyte Count. Evidence: 6/10. Source: PMID 39789286. Slightly Higher.
Showing effects for C/C genotype
Statin Muscle Pain. Evidence: 5/10. Source: PMID 18650507. ~17x Increased Risk.
Atorvastatin Clearance. Evidence: 4/10. Source: PMID 38493369. Slower Clearance.
Bilirubin Levels. Evidence: 4/10. Source: PMID 21646302. Higher Levels.
Monocyte Count. Evidence: 6/10. Source: PMID 39789286. Slightly Lower.
Showing effects for T/C genotype
Statin Muscle Pain. Evidence: 5/10. Source: PMID 18650507. ~4.5x Increased Risk.
Atorvastatin Clearance. Evidence: 4/10. Source: PMID 38493369. Slightly Slower.
Bilirubin Levels. Evidence: 4/10. Source: PMID 21646302. Slightly Higher.
Monocyte Count. Evidence: 6/10. Source: PMID 39789286. Typical.
What this genotype means for the people who carry it
Sample genotype: TT (Homozygous)
Carrying two copies of the T allele is associated with fully functional OATP1B1 transporters in the liver [1]. This allows for the efficient uptake and clearance of statins, such as simvastatin and atorvastatin, keeping their blood concentrations within a safe, therapeutic range [1] [2]. Consequently, the risk of developing statin-associated muscle symptoms, known as myopathy, remains at the typical baseline level [1] [3]. In contrast, individuals carrying the C allele experience a buildup of these drugs in the bloodstream, which can lead to muscle toxicity [1]. Bilirubin levels also remain within the typical range because the transporter effectively clears this byproduct from circulation [4]. Overall, this genotype represents the most common and favorable profile for standard statin therapies [1].
Typical statin clearance; Baseline risk of muscle pain.
Sample genotype: CC (Homozygous)
Carrying two copies of the C allele results in a severe reduction in OATP1B1 transporter activity in the liver [1]. This impairment significantly hinders the liver's ability to absorb and clear statins from the blood, leading to abnormally high drug concentrations [1] [2]. Research shows that individuals with this genotype face up to a 17-fold increased risk of developing statin-induced muscle pain, weakness, or the more severe muscle breakdown known as rhabdomyolysis [1] [3]. The effect is particularly pronounced with high doses of simvastatin, whereas other statins may be processed differently [1]. Because of the sluggish transport, circulating levels of bilirubin are also typically higher, which can act as a mild antioxidant but may occasionally cause harmless, slight yellowing of the skin or eyes [4]. Knowing this genetic profile helps guide personalized medication choices to avoid high-risk statin regimens [1].
Severely reduced statin clearance; Highly elevated risk of muscle pain.
Sample genotype: TC (Heterozygous)
Carrying one copy of the C allele is associated with a moderate reduction in the efficiency of the OATP1B1 liver transporter [1]. This slower transport rate causes certain cholesterol-lowering medications, particularly simvastatin, to linger in the bloodstream at higher concentrations [1] [2]. Clinical studies have demonstrated that this genotype is linked to an approximately 4.5-fold increased risk of developing statin-induced muscle pain or weakness [1] [3]. While many people with this genotype tolerate statins well, the elevated drug levels can sometimes trigger muscle toxicity, especially at higher doses [1]. Additionally, the reduced transporter activity can lead to slightly higher circulating levels of bilirubin, a natural antioxidant [4]. Healthcare providers often consider these genetic factors when choosing the most appropriate type and dose of statin therapy [1].
Slower statin clearance; Increased risk of muscle pain.
Variants with shared genetic architecture
rs4149056 · SLCO1B1 Gene · Chr 12 · Statin Side Effect Risk
rs11045819 · SLCO1B1 Gene · Chr 12 · Statin Response
rs4149081 · SLCO1B1 Gene · Chr 12 · Statin Response
SLCO1B1 variants and statin-induced myopathy--a genomewide study.
Content updated August 2026.
ReadYourDNA provides educational interpretation of DNA data you already have. It is not diagnostic, not a substitute for professional medical advice, diagnosis, or treatment, and is not intended to diagnose, treat, cure, or prevent any disease. Talk to a clinician before acting on any result.
Raw DNA Data Reports for 23andMe & AncestryDNA · About ReadYourDNA · FAQ · Methodology & Science · Pricing · Support and complaints · Legal & Contact · Health Traits · Pharmacogenomics · Carrier Status · Variant Explorer · The Human Karyotype · Privacy Policy · Terms of Service · Accessibility · Consumer Health Data Privacy · Your Privacy Choices · Editorial Standards · Your Data, Checkable · Sample Report · ReadYourDNA and Promethease compared · What is inside a 23andMe raw data file · What is inside an AncestryDNA raw data file · What a chatbot can and cannot do with your raw DNA file · Where a raw DNA file can still be uploaded in 2026
Written, maintained and operated by Martin Pechhacker, sole proprietor, Vienna, Austria. Trade register GISA 40064420. support@readyourdna.com