The USP18 gene helps control type I interferon, an antiviral alarm signal, and it also removes a small protein tag from other proteins to keep immune activity balanced. In medicine, this gene is important because it helps regulate when that alarm should quiet down after the body responds to a threat. If the gene does not work, interferon signaling can stay too active, which can lead to an inherited inflammatory condition that may affect the brain, skin, liver, and overall growth from early life.
What is a gene?
A gene is a section of DNA that carries instructions cells use to make molecules or regulate processes in the body. Some genes provide the directions for producing proteins, which are the functional parts of cells. Others mainly guide when certain processes happen, where they happen, and how active they are. In combination, genes affect how the body develops and works, and they can influence your response to food, stress, and medications. For a deeper look at this subject, see the LearnHub.
Overview
USP18Gene function
What if the gene works
The USP18 gene helps turn down part of the immune response after a virus triggers it. This keeps inflammation more controlled and also helps cells remove ISG15, a small protein tag linked to antiviral defense.
Risk
What if the gene does not work
More disruptive variants in the USP18 gene can cause an early onset condition driven by excess interferon, often called pseudo-TORCH syndrome, with brain inflammation, seizures, and feeding or breathing problems. Milder variants may cause later onset or less pronounced features.
Treatment
What does that mean for your treatment
For a pathogenic or loss of function variant in the USP18 gene, no USP18 specific treatment or management approach is currently established in clinical guidelines. The USP18 gene is being studied as a drug target and biomarker in cancer and some immune conditions, but this remains investigational.
Conditions associated with USP18
Gene function
What if the gene works
In your body, the USP18 gene supports processes that keep antiviral signals from staying on too long. It helps cells calm and shape type I interferon signaling, which is part of the body’s early defense against viruses. It also removes a small protein tag called ISG15 from other proteins. This is part of how the USP18 gene helps control immune signaling in daily cell activity.
One of its main roles is to help your cells keep type I interferon messages under control. Its protein helps limit how long this early antiviral alarm stays active, so immune responses remain measured.
The USP18 gene also removes ISG15, a small tag that cells attach to proteins during immune activity. Taking off this tag helps reset protein behavior and supports a balanced response.
What is a variant?
Genetic variants are small changes in the DNA sequence within a gene. They are common and are part of normal human diversity, including differences in appearance, metabolism, and how the body responds to environmental influences. Many do not have any noticeable effect and simply reflect natural variation in human genes. In some instances, 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
Changes in the USP18 gene can weaken or remove a brake on type I interferon signaling, a cell alarm system, so cells stay overactive longer than they should. This is how USP18 gene variants affect protein function: some missense variants reduce protein stability or its ability to bind signaling partners, while more disruptive truncating or splice variants can nearly abolish USP18 activity. Greater loss of function is often linked to earlier and more severe interferon related disease.
How variants are linked to conditions
Rare disease-causing variants in both copies of the USP18 gene cause USP18 deficiency, also called pseudo-TORCH syndrome 2, a rare inherited condition that starts before or soon after birth. This is one of the main conditions linked to USP18 gene variants, and it often includes brain calcifications, seizures, feeding and growth problems, low blood counts, and liver disease. In the right clinical setting, finding these variants can confirm the diagnosis.
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 have a direct impact on health and instead reflect natural human diversity. For many genes, carrying a variant associated with a condition indicates a possible link rather than a certain diagnosis, especially when more than one gene and environmental factors are involved. In some situations, however, 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 is not yet broadly confirmed evidence on specific factors that increase or reduce health risks related to the USP18 gene. For many living with a harmful USP18 change, risk is mainly linked to the genetic change itself rather than everyday lifestyle factors, so personal guidance from a doctor or genetic counselor is important.
Inheritance of USP18 variants
USP18-related conditions that have a well-established genetic basis are inherited in an autosomal recessive pattern. This means a child usually inherits one USP18 gene variant from each parent, and both parents are typically healthy carriers. When both parents carry a disease-causing variant in the USP18 gene, each pregnancy has a 25% chance of being affected, a 50% chance of resulting in a carrier child, and a 25% chance of resulting in a child without the familial variants. For families asking how USP18 variants are inherited, this pattern applies equally to boys and girls.
What does my USP18 result mean for my family?
For families with a disease-causing USP18 change linked to illness, the pattern is usually recessive, which means close relatives may be healthy carriers without knowing it. Brothers and sisters could also be affected or be carriers, and other blood relatives may carry the same change. Family testing can help clarify who else in the family may have the variant.
Genetic information
Genetic testing
How you find out about variants
USP18 genetic testing looks for variants in your DNA using a blood sample, saliva, or a cheek swab. It is usually done as part of a gene panel, exome sequencing, or genome sequencing, and the lab compares the USP18 gene with the usual sequence to identify variants that may help explain symptoms.
When should I consider getting a genetic test?
Consider testing the USP18 gene if a baby has severe inflammation starting before or soon after birth, especially with seizures, feeding problems, unusual brain scan findings, or a family history of similar illness. Testing can help confirm whether an inherited USP18 change is the cause.
A genetic result is only one part of your health story
A genetic result may offer useful insight, but what 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 works. In some conditions, especially those shaped by many genes, genetic information adds context rather than certainty and is best viewed alongside other parts of care. In other situations, a genetic result can provide a clear answer. In areas like medication response, genetic results can also help put individual experiences into context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. One person may break down a drug more slowly or more quickly than another, which can change how well it works or how likely side effects are. These differences are common and help explain why the same treatment can feel very different from one person to the next.
What is Pharmacogenetics?
Pharmacogenetics examines how differences in genes affect the way people respond to medications. It looks at gene and drug patterns 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 support more informed and individualized treatment decisions. To explore this topic further, you can learn more in the LearnHub.
Drugs influenced by the USP18 gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medication choices, so general questions about symptoms, side effects, or treatment are best discussed with your doctor. Research on USP18 has looked at whether it may affect response to interferon-based treatments, but this has not become part of routine prescribing.