The IL23A gene helps make part of an immune signal that tells certain white blood cells when to become active. If it does not work as expected, immune responses may become less balanced, which can affect inflammation and the body’s defense against germs. This gene plays an important role in communication between immune cells, especially in the skin and gut. Some variants in the IL23A gene are linked to inflammatory conditions such as psoriasis and inflammatory bowel disease, but they are only one part of the picture.
What is a gene?
Genes are sections of DNA that carry instructions your cells use to make molecules or direct processes in the body. Some genes provide the instructions for making proteins, the parts of cells that do much of the work. Others mainly help regulate when certain processes take place, where they occur, and how strongly they operate. Taken together, genes affect how the body develops and works, and they can influence how you respond to food, stress, or medications. To explore this subject in greater depth, you can find more in the LearnHub.
Overview
IL23AGene function
What if the gene works
The IL23A gene helps make part of IL-23, an immune messenger. This signal helps certain white blood cells respond to germs and coordinate inflammation, especially at barrier tissues like the gut and skin.
Risk
What if the gene does not work
Changes in the IL23A gene can reduce IL-23 signaling, an immune message that helps certain T cells work normally. Milder variants may cause small changes, while more severe variants can impair this pathway more clearly.
Treatment
What does that mean for your treatment
No IL23A-specific treatment or drug choice approach is currently established for people with a pathogenic or loss-of-function variant in the IL23A gene. The IL23A gene is part of the IL-23 pathway targeted by approved biologic medicines for psoriasis and some inflammatory bowel conditions, but those treatments are not chosen because of an IL23A variant.
Gene function
What if the gene works
Your immune system depends on clear chemical messages to respond in a measured way. The IL23A gene helps make one of these messages, called interleukin 23. This helps explain the IL23A gene’s role in immune system communication, especially at body surfaces such as the gut and skin.
The IL23A gene provides one part of interleukin 23, an immune messenger protein. Its protein joins with a partner made from the IL12B gene so cells can release the finished signal.
Interleukin 23 helps certain T cells stay active and send further immune signals. This gives the immune system a way to maintain a focused response when it meets germs.
This signaling is especially important at body linings such as the gut and skin, where microbes are common. It helps those tissues mount a controlled defense while continuing their everyday protective work.
What is a variant?
Within a gene, a genetic variant is a small change in its DNA sequence. These changes are common and help explain normal human diversity, such as differences in appearance, metabolism, or how the body responds to environmental influences. Many variants do not cause any noticeable effect and simply represent natural genetic variation. Sometimes, 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 IL23A gene can change how much IL-23 is made or how well its p19 protein folds, joins with IL12B, and is released from cells. Some changes affect regulatory DNA, which can raise or lower messenger RNA production, while others alter the protein itself and weaken assembly or stability. These IL23A gene variant effects on immune signaling are often mild, but more disruptive variants can markedly reduce or even stop IL-23 formation and downstream cell signaling.
How variants are linked to conditions
Current research on how IL23A gene variants are linked to conditions is still developing. The IL23A gene does not yet have a broadly confirmed link to a specific health condition in routine clinical genetics, and reported findings are still being clarified. Anyone with a confirmed IL23A-related test result should rely on guidance from their doctor or genetic counselor for personal interpretation.
A variant is not necessarily a diagnosis
Genetic variants are common across the general population and are a normal feature of human biology. Most do not directly affect health and instead reflect natural variation between people. For many genes, a variant associated with a condition points to a possible link rather than a certain diagnosis, particularly when several genes and environmental influences play a part. Still, in some situations, one well-characterized variant in a particular 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 IL23A. IL23A can be part of immune and inflammation pathways linked with conditions such as psoriasis or inflammatory bowel disease, but personal risk usually depends on many genes along with everyday factors like smoking, infections, and overall health.
Inheritance of IL23A variants
There is not yet a broadly confirmed Mendelian pattern for how IL23A gene variants are inherited in a specific IL23A related condition, so the answer to how IL23A gene variants are inherited remains cautious and research based. The IL23A gene is located on chromosome 12, which is an autosome. That means each person inherits one copy of the IL23A gene from each parent, and any inherited variant could come from either side of the family.
What does my IL23A result mean for my family?
There is not yet a broadly confirmed family inheritance pattern tied to a specific IL23A-related condition. Research on IL23A is still developing, and what a result means for relatives can depend a lot on the exact change that was found and why testing was done. A doctor or genetic counselor can help explain what, if anything, it could mean for close family members.
Genetic information
Genetic testing
How you find out about variants
Genetic testing for IL23A variants usually uses a blood or saliva sample. A lab reads the DNA sequence in the IL23A gene and compares it with the usual sequence to look for changes. Results may identify a benign variant, a variant of uncertain significance, or a variant linked to a health condition.
When should I consider getting a genetic test?
There is not yet a broadly established, IL23A-specific reason for genetic testing in routine care. Decisions about testing are usually based on your personal health history, family history, and the wider set of genes linked with immune or inflammatory conditions, best reviewed with a doctor or genetic counselor.
A genetic result is only one part of your health story
A genetic finding may offer useful insight, but how much it can tell you varies based on the condition and the kind of variant involved. Over time, many factors, including lifestyle, environment, age, and medical history, influence how the body functions. In some conditions, particularly those shaped by many genes, genetic information provides context rather than certainty and is best considered together with 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 a person’s individual experiences into perspective.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can influence how well a medicine works and how likely a person is to have side effects. One reason is that people break down, transport, or respond to drugs in different ways, so the same treatment can feel stronger in one person and weaker in another. These differences are common and are one part of why medication response varies from person to person. They can affect both how much benefit someone gets from a treatment and how sensitive their body is to it.
What is Pharmacogenetics?
Pharmacogenetics examines how differences in genes can affect the way someone responds to a medication. It focuses on links between genes and drugs to help explain why the same treatment may work differently from one person to another. For many medicines, genes can influence how strongly a drug works or how the body handles it. This information can help guide more informed and more individualized treatment decisions. You can read more about this topic in the LearnHub.
Drugs influenced by the IL23A gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medication choices. If you have concerns about side effects, how well a treatment is working, or changes to any medicine, talk with your doctor.
History
The IL23A gene entered modern medical research in 2000, when scientists identified a new immune signaling protein later named interleukin 23. Initially understood only through visible traits, later recognized as tied to a specific gene, this discovery helped separate IL-23 from the related molecule IL-12, which had long been grouped with it. From these first observations, research expanded steadily as studies linked the IL23A gene to inflammatory pathways involved in psoriasis, inflammatory bowel disease, and other immune conditions. During the 2000s, this work helped reshape how researchers classified certain long term inflammatory diseases. The IL23A gene is now part of the broader history of targeted immune research, especially in conditions where the IL-23 pathway became an important focus.