SLCO1B1: the transporter behind statin muscle side effects
Muscle aches are the most common reason people give up on a statin. SLCO1B1 is the best-established genetic reason some people get them at a dose others take without noticing.
Also known as: OATP1B1, solute carrier organic anion transporter family member 1B1.
What SLCO1B1 does
SLCO1B1 codes for OATP1B1, a transporter that sits on the surface of liver cells and pulls statins out of the bloodstream into the liver, where they act and are cleared. It is not an enzyme and it breaks nothing down; it moves things across a membrane. When the transporter works less well, a dose that would normally be swept into the liver stays circulating instead, and higher statin levels in blood and muscle are where the classic statin side effect comes from.
The transporter function groups
CPIC grades SLCO1B1 by how well the transporter works rather than by metabolizer speed, so the labels read normal function, decreased function and poor function, with increased function at the other end. The common decreased-function allele is called *5. One copy usually lands a person in decreased function, two copies in poor function. When a genotype does not resolve to a known combination, the answer is Indeterminate. The weaker the transporter, the more statin stays where it is not wanted.
Medications where it matters
simvastatin
Simvastatin depends on this transporter more than any other statin, which is why its guidance is the most pointed of the seven. Reduced transporter function raises simvastatin acid in the blood, and that is the exposure most closely tied to muscle injury.
| If your result is | Published CPIC guidance |
|---|---|
| Decreased Function | Per CPIC (A): "Prescribe an alternative statin depending on the desired potency (see Figure 1 of PMID: 35152405 for recommendations for alternative statins). If simvastatin therapy is warranted, limit dose to <20mg/day." |
| Increased Function | Per CPIC (A): "Prescribe desired starting dose and adjust doses based on disease-specific guidelines." |
| Normal Function | Per CPIC (A): "Prescribe desired starting dose and adjust doses based on disease-specific guidelines." |
| Poor Function | Per CPIC (A): "Prescribe an alternative statin depending on the desired potency (see Figure 1 of PMID: 35152405 for recommendations for alternative statins)." |
| Possible Decreased Function | Per CPIC (A): "Prescribe an alternative statin depending on the desired potency (see Figure 1 of PMID: 35152405 for recommendations for alternative statins). If simvastatin therapy is warranted, limit dose to <20mg/day." |
atorvastatin (Lipitor)
Atorvastatin is affected less than simvastatin and more than pravastatin. The published guidance caps the starting dose rather than steering to a different drug, which is a useful thing to know before assuming that one bad experience with a statin rules out the whole class.
| If your result is | Published CPIC guidance |
|---|---|
| Decreased Function | Per CPIC (A): "Prescribe ≤40mg as a starting dose and adjust doses of atorvastatin based on disease-specific guidelines. Prescriber should be aware of possible increased risk for myopathy especially for 40mg dose. If dose >40mg needed for desired efficacy, consider combination therapy (i.e., atorvastatin plus non-statin guideline directed medical therapy) (PMID: 30423391)." |
| Increased Function | Per CPIC (A): "Prescribe desired starting dose and adjust doses based on disease-specific guidelines." |
| Normal Function | Per CPIC (A): "Prescribe desired starting dose and adjust doses based on disease-specific guidelines." |
| Poor Function | Per CPIC (A): "Prescribe ≤20mg as a starting dose and adjust doses of atorvastatin based on disease-specific guidelines. If dose >20mg is needed for desired efficacy, consider rosuvastatin or combination therapy (i.e., atorvastatin plus non-statin guideline directed medical therapy) (PMID: 30423391)." |
| Possible Decreased Function | Per CPIC (A): "Prescribe ≤40mg as a starting dose and adjust doses of atorvastatin based on disease-specific guidelines. Prescriber should be aware of possible increased risk for myopathy especially for 40mg dose. If dose >40mg needed for desired efficacy, consider combination therapy (i.e., atorvastatin plus non-statin guideline directed medical therapy) (PMID: 30423391)." |
rosuvastatin (Crestor)
Rosuvastatin is handled by two transporters, SLCO1B1 and ABCG2, so CPIC reads them together. The rows below are the SLCO1B1 half, written assuming a typical ABCG2 result. The ABCG2 page covers the other half.
| If your result is | Published CPIC guidance |
|---|---|
| Decreased Function | Per CPIC (A): "Prescribe desired starting dose and adjust doses of rosuvastatin based on disease-specific and specific population guidelines. Prescriber should be aware of possible increased risk for myopathy especially for doses >20mg." |
| Increased Function | Per CPIC (A): "Prescribe desired starting dose and adjust doses of rosuvastatin based on disease-specific and specific population guidelines." |
| Indeterminate | Per CPIC (A): "Based on ABCG2 status, prescribe desired starting dose and adjust doses of rosuvastatin based on disease-specific and specific population guidelines. SLCO1B1 phenotype could not be assigned based on genotyping." |
| Normal Function | Per CPIC (A): "Prescribe desired starting dose and adjust doses of rosuvastatin based on disease-specific and specific population guidelines." |
| Poor Function | Per CPIC (A): "Prescribe ≤20mg as a starting dose and adjust doses of rosuvastatin based on disease-specific and specific population guidelines. If dose > 20mg needed for desired efficacy, consider combination therapy (i.e., rosuvastatin plus non-statin guideline directed medical therapy) (PMID: 30423391)." |
| Possible Decreased Function | Per CPIC (A): "Prescribe desired starting dose and adjust doses of rosuvastatin based on disease-specific and specific population guidelines. Prescriber should be aware of possible increased risk for myopathy especially for doses >20mg." |
pravastatin
Pravastatin sits at the tolerant end of the range. It is included here because knowing which statins this gene barely touches is as useful as knowing which ones it does.
| If your result is | Published CPIC guidance |
|---|---|
| Decreased Function | Per CPIC (A): "Prescribe desired starting dose and adjust doses of pravastatin based on disease-specific guidelines. Prescriber should be aware of possible increased risk for myopathy with pravastatin especially with doses >40mg per day." |
| Increased Function | Per CPIC (A): "Prescribe desired starting dose and adjust doses based on disease-specific guidelines." |
| Normal Function | Per CPIC (A): "Prescribe desired starting dose and adjust doses based on disease-specific guidelines." |
| Poor Function | Per CPIC (A): "Prescribe ≤40mg as a starting dose and adjust doses of pravastatin based on disease-specific guidelines. If patient is tolerating 40mg dose but higher potency is needed, a higher dose (>40mg) or an alternative statin (see Figure 1 of of [sic] PMID: 35152405 for recommendations for alternative statins) or combination therapy (i.e. pravastatin plus non-statin guideline directed medical therapy)(PMID: 30423391) could be considered. Prescriber should be aware of possible increased risk for myopathy especially with pravastatin doses >40mg." |
| Possible Decreased Function | Per CPIC (A): "Prescribe desired starting dose and adjust doses of pravastatin based on disease-specific guidelines. Prescriber should be aware of possible increased risk for myopathy with pravastatin especially with doses >40mg per day." |
Is this in your raw DNA file?
This is one of the pharmacogenes a plain consumer chip file can genuinely answer. The decreased-function *5 allele is tagged by a single position, rs4149056, and consumer genotyping arrays commonly include it, so Aimosti reads SLCO1B1 from a 23andMe or AncestryDNA export as part of the standard report rather than only from aligned reads. Two honest limits: rarer SLCO1B1 alleles are not on the chip, and a variant-only file cannot prove a position was covered. If rs4149056 is absent from your file, that could mean you carry the reference allele or it could mean the position was never read, and the report says so instead of calling it clean.
A genotyping chip reads only a few hundred thousand pre-selected positions, about 0.02% of your genome, chosen for common variation. It does not sequence the rest, so it cannot find the rare or novel pathogenic variants the clinical and carrier modules look for: a “no finding” from chip data means “this chip never looked”, far more so than with whole-genome sequencing. Chip data suits common-variant traits, pharmacogenomic tag SNPs, and haplogroup ancestry, not clinical or carrier screening.
Common questions
Is SLCO1B1 in my 23andMe or AncestryDNA raw data?
Usually. The key position, rs4149056, is a common consumer-chip marker, and Aimosti reads it from the file you already have. If it is missing from your export, the result is reported as unresolved rather than assumed to be reference.
Does a decreased-function result mean my muscle aches came from the gene?
No. It means one contributing factor is present. Statin muscle symptoms have causes that have nothing to do with SLCO1B1, and plenty of people with a decreased-function result take statins without trouble. What the result gives you is one concrete thing to put in front of a prescriber instead of a vague report of aching.
Should I stop my statin if the result is decreased or poor function?
No. Stopping a statin has its own risk, and this result is not a reason to do it unilaterally. The published guidance is mostly about starting dose and drug choice, both of which are prescriber decisions.
Why does the same gene give different advice for different statins?
Because the statins differ in how much they rely on this transporter to reach the liver. CPIC publishes a separate recommendation for each of the seven, and the tables above keep them separate for that reason.