The TTR gene gives your body instructions to make transthyretin, a protein that carries thyroid hormone and helps move vitamin A through the blood. If this protein becomes unstable, it can clump into amyloid, a buildup that may affect the nerves, heart, and other tissues. Some people with variants in the TTR gene develop hereditary transthyretin amyloidosis, which can cause numbness, weakness, dizziness on standing, or heart failure symptoms. Other people develop a similar protein buildup later in life without an inherited TTR variant.
What is a gene?
Genes are sections of DNA that carry instructions your cells use to make molecules or regulate activities in the body. Some genes provide the code for proteins, the parts of cells that do much of the work. Others mainly guide when certain processes happen, where they take place, and how strongly they are carried out. As a group, genes affect how the body develops and works, and they can influence how you respond to food, stress, and medications. For a more detailed look at this topic, you can find more in the LearnHub.
Overview
TTRGene function
What if the gene works
The TTR gene helps make transthyretin, a protein that carries thyroid hormone and vitamin A through the blood. It is made mainly in the liver and also helps transport these nutrients in fluid around the brain.
Risk
What if the gene does not work
Variants in the TTR gene can make transthyretin unstable, so it misfolds and builds up as amyloid. This may affect nerves and the heart, causing symptoms that range from later, milder disease to earlier, more extensive amyloidosis.
Treatment
What does that mean for your treatment
A pathogenic variant in the TTR gene can guide use of TTR targeted treatment. Depending on whether nerve or heart involvement is present, care may include a stabilizer such as tafamidis or gene silencing medicines such as patisiran, vutrisiran, inotersen, or eplontersen. Liver transplant is used less often now, but it may still be considered in selected hereditary cases.
Conditions associated with TTR
Gene function
What if the gene works
In day to day life, the TTR gene helps your body move thyroid hormone and vitamin A to where they are needed. It does this by making a transport protein that circulates in the blood and in the fluid around the brain. This is a central part of what the TTR gene does in the body each day.
Its protein carries some thyroxine, a thyroid hormone, through the blood and the fluid around the brain. This helps deliver a hormone that supports energy use, growth, and many routine body functions.
Its protein binds to retinol-binding protein, the main carrier that moves vitamin A in the blood. This helps vitamin A stay in circulation so tissues such as the eyes and immune system can use it.
What is a variant?
A genetic variant is a small alteration in the DNA sequence of a gene. These changes are common and help explain normal human diversity, including differences in appearance, metabolism, or how the body responds to environmental influences. Many variants do not have any noticeable effect and simply represent natural genetic variation. In some cases, though, a variant can change a gene’s function more substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the TTR gene can change the shape and stability of transthyretin, making the protein more likely to misfold and build up as amyloid (protein clumps) in tissues. This is the core of how TTR gene variants affect protein folding and function. Some variants have a milder effect on stability, while others make the protein much more prone to clumping. That difference can influence whether transthyretin amyloidosis appears later or earlier and how strongly it affects the body.
How variants are linked to conditions
Pathogenic variants in the TTR gene cause hereditary transthyretin amyloidosis, an inherited condition that may affect the nerves, heart, eyes, and sometimes the tissues around the brain and spinal cord. TTR gene amyloidosis symptoms often include numbness or burning in the feet, weakness, dizziness on standing, digestive changes, or signs of cardiomyopathy. Some variants are linked mainly to nerve disease, others more strongly to heart involvement, and some to both.
A variant is not necessarily a diagnosis
Genetic variants are a common and expected part of human biology across the general population. Most do not directly affect health and simply reflect natural human diversity. For many genes, having a variant associated with a condition points to a possible link rather than a certain diagnosis, particularly when more than one gene and environmental influences play a role. In some situations, though, one well-characterized variant in a particular gene is enough to confirm a diagnosis.
Are there things that can increase or change my risk?
For TTR, risk is shaped mainly by the specific gene change you carry, your family background, and age. In many living with a disease-causing TTR change, problems become more likely in adulthood and often later in life, and for some TTR changes, risk can also differ by sex and ancestry.
Inheritance of TTR variants
Variants in the TTR gene are usually inherited in an autosomal dominant pattern. This means a parent with a disease-causing TTR variant can pass it to a child with a 50% chance in each pregnancy, whether the child is a son or a daughter. In practical terms, when people ask how TTR gene variants are inherited, the answer is that one altered copy can be enough to run in families across generations. Not everyone who inherits a TTR variant will have the same symptoms, age of onset, or health effects.
What does my TTR result mean for my family?
For many living with a harmful change in the TTR gene, close relatives can also carry the same change because this condition usually runs in families in a dominant pattern. That means parents, brothers, sisters, and children may also have a chance of having the variant. Family members may want to learn whether the same TTR result is present, especially if there is a history of nerve problems or heart amyloid disease in the family.
Genetic information
Genetic testing
How you find out about variants
TTR genetic testing looks for variants in the TTR gene using a blood or saliva sample. A lab reads the gene's DNA to see whether a variant linked to hereditary transthyretin amyloidosis is present. Results can confirm an inherited cause in someone with suggestive symptoms or identify a familial variant in relatives.
When should I consider getting a genetic test?
Consider TTR genetic testing if you or close relatives have unexplained numbness or burning in the feet or hands, repeated carpal tunnel syndrome, or a thick, stiff heart linked to amyloidosis, a harmful protein buildup. It can also help when a family member has a known TTR variant, because relatives may carry the same change.
A genetic result is only one part of your health story
A genetic finding can provide useful insight, but the amount it reveals depends on the condition and on the kind of variant present. Many factors, including lifestyle, environment, age, and medical history, influence how the body functions over time. For some conditions, particularly those shaped by many genes, genetic information offers context rather than certainty and makes most sense when considered with other parts of care. In other situations, a genetic result can give a clear answer. In areas like medication response, it can also help put personal experiences in context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. This helps explain why the same treatment works well for one person, does less for another, or causes more side effects in someone else. Small inherited differences can change how the body breaks down a drug, moves it through the body, or responds to it at its target, and these differences are common.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences can shape a person’s response to medicines. By looking at connections between genes and drugs, it helps explain why the same treatment may work differently from one person to another. For many medications, genes influence how strongly a drug works or how the body breaks it down. This information can support treatment decisions that are more informed and more personalized. More detail on this topic is available in the LearnHub.
Drugs influenced by the TTR gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in predicting how people respond to medicines, so questions about treatment, side effects, or new symptoms are best discussed with your doctor. Researchers are studying whether different TTR changes may affect response to treatments for transthyretin amyloidosis, but this is not yet a routine guide for prescribing.
History
The history of the TTR gene is closely tied to the discovery of inherited amyloidosis, a condition in which an abnormal protein builds up in tissues over time. In the mid 20th century, doctors in Portugal, Sweden, and Japan described families with similar nerve symptoms and traced the pattern through generations. Initially understood only through visible traits, later recognized as tied to a specific gene, this work helped connect a family illness to a clear inherited cause. In the 1980s, researchers identified variants in the TTR gene as the explanation for many of these cases. That finding marked an important step in medical genetics because it linked DNA changes to a specific protein buildup disease. Since then, the TTR gene has remained central to research on inherited amyloidosis and its treatment.