The SLCO1B1 gene helps make a liver transport protein that moves certain medicines and natural substances from the blood into the liver. This gene can play a role in how your body responds to statins and some other drugs. If it works less well, medicine levels can rise in the bloodstream and may increase the chance of side effects, especially muscle symptoms with some statins. Rare severe variants in both copies of the gene can also affect bilirubin, a yellow pigment made when red blood cells break down.
What is a gene?
A gene is a stretch of DNA that holds instructions your cells use to make molecules or guide processes in the body. Some genes provide the directions for building proteins, which are the working parts of cells. Others mainly help regulate when certain processes happen, where they take place, and how active they are. Taken together, genes affect how the body grows and works, and they can influence how you respond to food, stress, or medicines. For a deeper look at this topic, you can read more in LearnHub.
Overview
SLCO1B1Gene function
What if the gene works
The SLCO1B1 gene helps liver cells pull certain substances from the blood. These include bilirubin, bile acids, hormones, and some medicines, which supports normal liver processing and removal.
Risk
What if the gene does not work
Reduced-function variants in the SLCO1B1 gene can raise statin levels and increase muscle side effect risk, with milder and more severe variants affecting how strong this is. Rarely, loss of SLCO1B1 with SLCO1B3 causes Rotor syndrome with jaundice.
Treatment
What does that mean for your treatment
Many people with decreased-function variants in the SLCO1B1 gene are often steered away from simvastatin, especially at higher doses, because blood levels rise and muscle side effects become more likely. Care may shift to another statin, such as pravastatin or rosuvastatin, or to a lower-intensity approach when statin treatment is needed.
Conditions associated with SLCO1B1
Gene function
What if the gene works
In your liver, the SLCO1B1 gene helps move selected substances from the blood into liver cells. Its protein sits on the cell surface and acts like an entry gate for certain body chemicals. This steady transport supports everyday liver work and helps clear compounds from the bloodstream.
The SLCO1B1 gene helps liver cells take in certain substances circulating in the blood. This is part of how the liver receives materials it needs to process and clear.
Its protein transports compounds such as bilirubin, a yellow substance made when old red blood cells are broken down. Moving these substances into liver cells helps the body prepare them for removal.
It also carries some bile acids, products made from hormones, and certain medicines into liver cells. This shows how the SLCO1B1 gene helps move medicines and body chemicals into the liver as part of normal liver function.
What is a variant?
A genetic variant is a small change in the DNA sequence within a gene. These changes are common and are part of normal human diversity, such as differences in appearance, metabolism, or the way the body responds to environmental influences. Many variants do not have any noticeable effect and simply represent natural genetic variation. In some situations, however, a variant can change how a gene functions more substantially and may contribute to, or cause, a genetic condition.
Genetic variants
What if the gene does not work
Variants in the SLCO1B1 gene can change the shape, stability, or cell-surface placement of its transporter protein, so liver cells take up certain medicines less efficiently. This helps explain how SLCO1B1 gene variants affect statin transport in the body. Some variants have a mild effect and only partly reduce transport activity, while more severe variants can markedly lower it or nearly stop it. Stronger loss of function often leads to higher drug levels in the blood.
How variants are linked to conditions
Certain variants in the SLCO1B1 gene are most clearly linked to a higher chance of statin muscle pain and weakness, especially with simvastatin. This SLCO1B1 gene and statin muscle pain link is well established and is used in some prescribing guidance. These variants affect risk, not certainty, so many people with them take statins without muscle symptoms.
A variant is not necessarily a diagnosis
Variants in genes are a usual feature of human biology and are widespread across the population. Most do not directly affect health and simply contribute to normal human diversity. For many genes, having a variant associated with a condition points to a potential link, not a certain diagnosis, particularly when several genes and environmental influences play a role. In some situations, though, one well-characterized variant in a particular gene is enough to confirm the diagnosis.
Are there things that can increase or change my risk?
For SLCO1B1, risk mainly changes when taking certain statin cholesterol medicines rather than causing illness on its own. Reduced-function changes in this gene can raise the chance of muscle pain or muscle injury, especially with simvastatin and higher doses. Risk can also be higher with older age, kidney problems, or medicines that interact with statins.
Inheritance of SLCO1B1 variants
There is not yet a broadly confirmed single-gene inheritance pattern for how SLCO1B1 variants are inherited in relation to a specific inherited condition. Most well-known SLCO1B1 changes are discussed because they can influence how your body handles certain medicines, rather than because they follow a clear autosomal dominant or autosomal recessive disease pattern on their own. The SLCO1B1 gene is located on chromosome 12, which is an autosome, so you inherit one copy from each parent. That means either parent can pass an SLCO1B1 variant to a child.
What does my SLCO1B1 result mean for my family?
There is not a broadly confirmed, single-gene inheritance pattern for SLCO1B1 that usually lets families predict who will have a specific health condition. Most SLCO1B1 results are used to understand how someone may respond to certain medicines, especially some statins, rather than to diagnose an inherited condition. If you have a specific SLCO1B1 result and want to know what it could mean for relatives, a doctor or genetic counselor can explain it in the context of your family.
Genetic information
Genetic testing
How you find out about variants
SLCO1B1 genetic testing for statin side effects uses a saliva or blood sample to look for specific variants in the SLCO1B1 gene. A lab reads the DNA code at known spots and reports whether you carry a variant that may affect how your body handles some statin medicines.
When should I consider getting a genetic test?
Testing for the SLCO1B1 gene may be worth discussing if you are about to start simvastatin or have had unusual muscle pain, weakness, or dark urine while taking a statin. It can also help explain a strong family pattern of statin muscle side effects and may guide safer medication choices.
A genetic result is only one part of your health story
Genetic results can be informative, but what they tell you depends on the condition and the kind of variant involved. Many factors, including lifestyle, environment, age, and medical history, also shape how the body functions over time. For some conditions, especially those influenced by many genes, genetic information offers context rather than certainty and is best considered alongside other parts of care. In other situations, a genetic result may give a clear answer. In areas like medication response, genetic results can also help put personal experiences into perspective.
Pharmacogenetics
How variants shape your response to medicine
Some variants in the SLCO1B1 gene can change how your body handles certain statins, which are medicines used to lower cholesterol. This gene helps move these drugs from the bloodstream into the liver, so a reduced function variant can leave more of the medicine in the blood. That can increase the chance of muscle side effects in some people, especially with simvastatin. Genetic differences like this are common and help explain why the same medicine may work differently or feel harder to tolerate from one person to another.
What is Pharmacogenetics?
Pharmacogenetics examines how differences in a person’s genes can affect the way they respond to medicines. It studies gene-drug relationships to help explain why the same treatment may not work in the same way for everyone. With many drugs, genes influence both how the body handles the medicine and how strong its effects are. This information can support treatment choices that are more informed and more personalized. More detail on this subject is available in the LearnHub.
Drugs influenced by the SLCO1B1 gene
When should I seek medical advice?
SLCO1B1 can affect how your body handles some statin cholesterol medicines. It is worth talking with your doctor before starting or changing a statin, especially if you or a close relative have had muscle pain or weakness with one. Seek medical advice promptly if muscle aches are strong, unusual, or come with dark urine or severe weakness.
History
The SLCO1B1 gene entered medical genetics through research on how the liver handles medicines and other compounds in the blood. In recent decades, awareness of this gene’s role has grown as studies linked certain SLCO1B1 variants to a higher chance of muscle side effects with some statins. A major step came in 2008, when a widely cited study connected a common SLCO1B1 variant with statin related muscle symptoms, bringing the gene into everyday pharmacogenetics discussions. From these first observations, research expanded steadily, and expert groups later began using SLCO1B1 results to help guide statin prescribing. Today, the SLCO1B1 gene is one of the best known examples of how inherited differences can shape medicine response.