The SLCO1C1 gene helps move thyroid hormone, especially thyroxine (T4), from the blood into the brain, where it supports normal brain development and function. This gene plays an important role in helping brain cells get the hormone signals they need for energy use and day to day brain activity. If the gene does not work properly, thyroid hormone transport in the brain may be reduced, which can affect nervous system function. Researchers also study common variants in the SLCO1C1 gene for possible links to how some medicines are handled.
What is a gene?
Genes are sections of DNA that hold instructions your cells use to make molecules or manage processes throughout the body. Some genes provide the directions for making proteins, which are the parts of cells that do much of the work. Others mostly help regulate when certain processes happen, where they happen, and how active they are. Taken together, genes affect how the body grows and works, and they can influence how you react to food, stress, and medications. For a deeper look at this topic, more information is available in the LearnHub.
Overview
SLCO1C1Gene function
What if the gene works
The SLCO1C1 gene helps move thyroid hormones, especially T4, from the blood into certain cells. This is especially important at the blood-brain barrier, where it supports normal hormone delivery to the brain.
Risk
What if the gene does not work
More severe variants in the SLCO1C1 gene can reduce thyroid hormone entry into the brain and cause a rare neurodevelopmental condition with developmental delay and movement problems. Milder variants may lead to less severe features.
Treatment
What does that mean for your treatment
No SLCO1C1-specific treatment or drug selection approach is currently established in clinical guidelines for people with pathogenic or loss-of-function variants in the SLCO1C1 gene. The SLCO1C1 gene is being studied for its role in moving thyroid hormone into the brain, which may help guide future targeted treatments.
Gene function
What if the gene works
Your brain depends on carefully controlled movement of thyroid hormones. The SLCO1C1 gene helps with that movement by making a transporter in cell membranes. It is best known for helping key thyroid hormones enter the brain and certain other cells.
The SLCO1C1 gene helps make a transporter protein that moves thyroid hormones from the blood into certain cells. It is especially active at the blood-brain barrier, where it supports thyroid hormone transport into the brain.
By bringing in thyroxine (T4), this gene helps the brain keep a steady local hormone supply. That supports normal signaling in brain cells, which depends on the right amount of thyroid hormone reaching the tissue.
Its protein sits in the cell membrane and acts like a selective gate for certain hormone molecules. This allows uptake to be more controlled than simple passive movement across the membrane.
What is a variant?
A genetic variant is a minor difference in the DNA sequence within a gene. These differences are common and help explain normal variation among people, such as differences in appearance, metabolism, or how the body responds to environmental influences. Many have no noticeable effect and are simply part of natural genetic variation. Sometimes, though, a variant changes how a gene functions more substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
SLCO1C1 gene variants can change the shape, stability, or cell-surface trafficking of its transporter protein, so less thyroid hormone reaches the brain across the blood-brain barrier. In practice, how SLCO1C1 gene variants affect transporter function ranges from milder changes that partly reduce transport to more severe variants that nearly abolish it. This loss of function can lead to a wider range in how early related neurologic features appear and how marked they become.
How variants are linked to conditions
Variants in the SLCO1C1 gene do not yet have a broadly confirmed link to a specific health condition, though research on how variants in the SLCO1C1 gene are linked to conditions is still developing. Anyone with a confirmed SLCO1C1-related diagnosis should rely on guidance from their doctor or genetic counselor rather than general information.
A variant is not necessarily a diagnosis
Genetic variants are a usual part of human biology and are common across the general population. Most do not directly affect health and instead represent normal human variation. For many genes, having a variant associated with a condition suggests a possible link rather than a definite diagnosis, especially when several genes and environmental factors also play a role. In some cases, though, a single well understood variant in a particular gene is enough to confirm a diagnosis.
Are there things that can increase or change my risk?
There is not yet broadly confirmed evidence on specific factors that increase or reduce health risk related to the SLCO1C1 gene. If a change in SLCO1C1 is found on testing, a doctor or genetic counselor can help explain what it may mean for your personal and family risk.
Inheritance of SLCO1C1 variants
SLCO1C1-related conditions are inherited in an autosomal recessive pattern. This means a person usually develops the condition only when they inherit two disease-causing variants in the SLCO1C1 gene, one from each parent. Parents who carry one variant are typically carriers and usually do not have the condition themselves. For families asking about the SLCO1C1 gene inheritance pattern, each pregnancy between two carriers has a 25% chance of an affected child, a 50% chance of a carrier child, and a 25% chance of a child with neither variant.
What does my SLCO1C1 result mean for my family?
For families with a disease-causing SLCO1C1 change linked to the known condition in this gene, the pattern is usually recessive. This often means parents can be healthy carriers, and brothers or sisters may also be carriers or, in some families, may also be affected. Close relatives may want to learn whether the same result is present in them, especially when there is a family history of similar symptoms.
Genetic information
Genetic testing
How you find out about variants
To look for changes in the SLCO1C1 gene, a lab can test DNA from a blood sample, saliva, or a cheek swab. SLCO1C1 genetic testing reads the gene’s DNA code and checks for known variants or other changes. Results may show a variant, no variant, or a change whose health meaning is not yet clear.
When should I consider getting a genetic test?
Consider genetic testing for the SLCO1C1 gene if a child has unexplained early developmental delay, low muscle tone, or unusual movements and doctors suspect a rare inherited condition affecting thyroid hormone movement into the brain. Testing can also make sense when a close family member has a known SLCO1C1 variant.
A genetic result is only one part of your health story
A result from genetic testing can provide useful insight, but how much it can tell you varies based on the condition and the type of variant involved. Over time, many factors, including lifestyle, environment, age, and medical history, influence how the body functions. For some conditions, especially those shaped by many genes, genetic information offers context rather than certainty and is best understood together with other parts of care. In other situations, a genetic result may give a clear answer. In areas such as medication response, genetic results can also help put individual experiences into perspective.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can influence how your body handles medicines, so the same treatment may work well for one person but less well, or cause more side effects, in another. Small differences in genes can affect how a drug is absorbed, moved through the body, broken down, or reaches its target. This kind of variation is common and can shape both how strongly a medicine works and how sensitive someone may be to it.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences affect the way people respond to medications. It studies gene-drug patterns to help explain why the same treatment may work differently from one person to another. For many medicines, genes influence how the body processes a drug and how strong its effects are. This information can support more informed, individualized treatment decisions. If you want to learn more about this topic, more information is available in the LearnHub.
Drugs influenced by the SLCO1C1 gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medication choice or dose. For side effects, medication changes, or other health concerns, talk with your doctor.