The IL17A gene helps the immune system send signals that call white blood cells to fight germs, especially at the skin, mouth, lungs, and gut. This gene plays an important role in defending against some bacteria and fungi and in controlling inflammation. If the IL17A gene does not work properly, some people may have repeated yeast infections such as thrush and other infections on body surfaces. Too much IL17A activity can also contribute to inflammatory conditions such as psoriasis and some forms of arthritis.
What is a gene?
A gene is a stretch of DNA that carries instructions your cells use to make molecules or manage processes throughout the body. Some genes provide the directions for producing proteins, which are the parts of cells that do much of the work. Others are mainly involved in regulating 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 also influence your response to food, stress, or medicines. For a more detailed explanation of this topic, you can find more in the LearnHub.
Overview
IL17AGene function
What if the gene works
The IL17A gene helps immune cells send signals that call in other defenders during infection. This supports inflammation, especially at the skin and lining of the mouth, lungs, and gut, to fight bacteria and fungi.
Risk
What if the gene does not work
Variants in the IL17A gene can range from milder changes to more severe ones. They may reduce or block the IL-17A signal, making cells less able to call in infection-fighting white blood cells and support barrier surfaces.
Treatment
What does that mean for your treatment
No IL17A-specific treatment or management approach is currently established for people with a pathogenic or loss of function variant in the IL17A gene. Separately, IL17A is a well-established drug target, and medicines that block IL-17A are used for some inflammatory conditions.
Gene function
What if the gene works
Your body uses the IL17A gene to help direct quick immune responses at places that meet the outside world, like the skin, airways, and gut. It mainly works as part of your normal defense against bacteria and fungi. Understanding how the IL17A gene supports the immune system helps explain its day to day role in keeping protective barriers ready.
The IL17A gene gives certain immune cells instructions to make IL-17A, a chemical messenger. This messenger helps nearby cells know when extra local defense is needed.
IL-17A acts strongly at body surfaces such as the skin, lungs, and gut lining. It helps these tissues make protective signals and surface proteins that support a healthy barrier against everyday germs.
One of its main roles is to help your body call neutrophils, a type of white blood cell, to the right place. These cells are important for clearing bacteria and fungi during routine immune defense.
The IL17A gene also helps tissues release antimicrobial proteins, which are natural substances that limit microbe growth. This supports a faster, more organized response where germs first enter the body.
What is a variant?
A genetic variant is a minor difference in the DNA sequence of a gene. These differences are common and help shape normal human diversity, such as variation 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, though, 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
Changes in the IL17A gene can alter how much IL-17A is made, how stable the protein is, and how well it binds its partner receptors, which can weaken or occasionally strengthen cell signaling. In practical terms, how variants in the IL17A gene affect immune signaling depends on the change: milder variants may slightly shift gene activity, while more disruptive variants can markedly reduce protein production, release, or receptor binding.
How variants are linked to conditions
Current evidence on how IL17A gene variants are linked to conditions is still developing. The IL17A gene does not yet have a broadly confirmed link to one specific health condition in routine clinical genetics, although research findings may evolve over time. If you carry a reported variant in the IL17A gene, your care is best guided by your doctor or genetic counselor in the context of your symptoms, family history, and test results.
A variant is not necessarily a diagnosis
Genetic variants are common and are a normal part of human biology. Most do not directly affect health and simply contribute to natural human diversity. For many genes, carrying a variant associated with a condition indicates a possible link rather than a definite diagnosis, especially when multiple genes and environmental factors play a role. In some situations, though, a single well-characterized variant in a specific gene is enough to confirm a diagnosis.
Are there things that can increase or change my risk?
There isn't yet broadly confirmed evidence on specific factors that increase or reduce risk related to IL17A itself. IL17A changes are usually looked at as one small part of immune-related risk, alongside many other genes and everyday factors such as smoking, infections, and overall health.
Inheritance of IL17A variants
There is not yet a broadly confirmed, single disease-specific inheritance pattern for how IL17A gene variants are inherited, because most reported IL17A findings relate to immune traits or risk rather than a well-established Mendelian condition. In practical terms, how IL17A gene variants are inherited is still being clarified as research develops. The IL17A gene is located on chromosome 6, which is an autosome, so you inherit one copy from each parent.
What does my IL17A result mean for my family?
There isn't yet a broadly confirmed inheritance pattern tied to a specific condition for IL17A, though this understanding can change as research develops. If you have a specific IL17A result and questions about what it could mean for your family, a doctor or genetic counselor can help explain it in the context of your personal and family history.
Genetic information
Genetic testing
How you find out about variants
To look for IL17A variants, genetic testing uses a blood or saliva sample and reads the DNA code in the IL17A gene for changes. Genetic testing for IL17A variants is usually done through a multigene panel or broader DNA sequencing, and the report labels each variant as benign, uncertain, or linked to disease.
When should I consider getting a genetic test?
There is not yet a broadly established IL17A-specific reason for genetic testing in routine care. Testing decisions are usually based on your personal health history, family history, and the wider clinical picture, ideally with guidance from a doctor or genetic counselor.
A genetic result is only one part of your health story
A genetic result can provide useful insight, but how much it explains varies with the condition and the kind of variant involved. Over time, many factors, including lifestyle, environment, age, and medical history, also influence how the body functions. For some conditions, particularly those shaped by many genes, genetic information offers context rather than certainty and is most helpful when considered together with other parts of care. In other situations, a genetic result can give a clear answer. In areas such as medication response, genetic results may also help make individual experiences easier to understand.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. A treatment that works well for one person may work less well for another, or may cause more side effects, because the body can absorb, break down, or respond to a drug differently. This kind of variation is common and is one reason medication response is not the same for everyone. In some cases, these inherited differences can influence how effective a treatment feels or how sensitive someone is to it.
What is Pharmacogenetics?
Pharmacogenetics examines how differences in genes can affect the way a person responds to medicines. It studies gene drug patterns to help explain why the same treatment may work differently in different people. With many medications, genes can influence how much effect a drug has or how the body handles it. This information can support treatment choices that are better informed and more individualized. More detail on this topic is available in the LearnHub.
Drugs influenced by the IL17A gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medication choices, so questions about side effects, new medicines, or changes in treatment are best discussed with your doctor. IL17A has been studied in research on how some people respond to targeted immune medicines for psoriasis and other inflammatory conditions, but this is not used routinely to make treatment decisions.
History
The IL17A gene entered the scientific literature in the early 1990s, when researchers identified a new immune signaling gene that was first called CTLA8. From these first observations, research expanded steadily. As scientists mapped related genes, CTLA8 was reclassified and became known as the IL17A gene, helping define the broader IL17 family. Interest in this gene grew as studies linked it to inflammatory pathways involved in conditions such as psoriasis and other immune mediated diseases. That work helped shape a major shift in immunology, moving attention toward targeted treatments aimed at the IL17 pathway. Over time, the IL17A gene became established as an important landmark in the modern history of inflammation research.