The IFNGR1 gene helps immune cells receive signals from interferon gamma, a messenger that tells them how to control germs hiding inside cells. If this gene does not work well, the body may have trouble fighting certain infections, especially mycobacteria such as the BCG vaccine strain and some causes of tuberculosis, and sometimes salmonella. In medicine, this gene is important because variants can cause an inherited immune condition called Mendelian susceptibility to mycobacterial disease.
What is a gene?
Genes are sections of DNA that carry instructions your cells use to make molecules or regulate processes in the body. Some genes provide the information needed to make proteins, the working parts of cells. Others mainly help control when certain processes happen, where they happen, and how strongly they are carried out. Together, genes affect how the body develops and works, and they can also influence how you respond to food, stress, or medications. For a closer look at this topic, you can find more in the LearnHub.
Overview
IFNGR1Gene function
What if the gene works
The IFNGR1 gene helps many cells receive interferon gamma signals from the immune system. This turns on defenses that help control germs, especially bacteria that live inside cells.
Risk
What if the gene does not work
Variants in the IFNGR1 gene can weaken an immune signal called interferon gamma, increasing risk of mycobacterial infections, including severe illness after BCG vaccination. Milder variants may cause later, less severe disease than more disruptive variants.
Treatment
What does that mean for your treatment
Pathogenic variants in the IFNGR1 gene can change treatment choice. With complete IFNGR1 loss, interferon gamma treatment usually does not help, so care relies on prolonged antimycobacterial antibiotics and hematopoietic stem cell transplant in selected people. With partial IFNGR1 deficiency, some may still respond to interferon gamma alongside antibiotics.
Conditions associated with IFNGR1
Gene function
What if the gene works
Your immune system uses the IFNGR1 gene to hear one of its key alarm signals, called interferon gamma. This signal helps white blood cells know when to step up their response to germs, especially microbes that can live inside cells. When this gene works properly, cells receive the message clearly and carry out a coordinated defense.
The IFNGR1 gene makes the part of a receptor on the cell surface that recognizes interferon gamma. This allows many cells, especially immune cells, to detect an important call to action.
Once interferon gamma attaches, the receptor helps carry that message into the cell. This turns on sets of genes that support immune activity and help cells respond in a more organized way.
Signals through this pathway help macrophages, a type of white blood cell, become better at containing germs they have taken in. It is especially important for the immune system response to bacteria that live inside cells.
IFNGR1 signaling can raise how well cells present small pieces of germs to T cells. That helps different parts of the immune system recognize problems and work together.
What is a variant?
A genetic variant is a small difference in the DNA sequence within a gene. These differences are common and help account for normal human diversity, including variation in appearance, metabolism, and 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 changes how a gene functions more substantially and can contribute to, or cause, a genetic condition.
Genetic variants
What if the gene does not work
Variants in the IFNGR1 gene can weaken interferon gamma signaling by changing the receptor’s shape, reducing how much reaches the cell surface, or blocking the signal after binding. Some IFNGR1 gene variants that reduce interferon gamma signaling cause only partial loss of activity, while more severe variants can leave the receptor absent or nonworking. This range in functional impact often parallels the associated infection tendency, with more complete loss usually linked to earlier and more pronounced infections.
How variants are linked to conditions
Pathogenic variants in the IFNGR1 gene cause a rare inherited immune condition called Mendelian susceptibility to mycobacterial disease. People with Mendelian susceptibility to mycobacterial disease caused by IFNGR1 variants can become ill from the BCG vaccine strain or from mycobacteria in the environment that usually do not cause major problems. Some also have repeated Salmonella infections.
A variant is not necessarily a diagnosis
Genetic variants are a routine feature of human biology and are widespread in the general population. Most do not directly affect health and instead reflect normal human diversity. For many genes, carrying a variant associated with a condition suggests a possible link rather than a definite diagnosis, especially when several genes and environmental factors are involved. 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?
For people with a harmful IFNGR1 change, the chance of serious infection is driven mainly by the gene change itself, especially after exposure to certain germs such as the live BCG vaccine or some mycobacteria in the environment. There is not enough evidence to say lifestyle changes lower this risk, so the focus is usually on avoiding known triggers when relevant and watching closely for early signs of infection.
Inheritance of IFNGR1 variants
For IFNGR1-related conditions, how IFNGR1 variants are inherited depends on the specific variant and the condition it causes. Some follow an autosomal recessive pattern, which means a child inherits one altered copy of the IFNGR1 gene from each parent. Others follow an autosomal dominant pattern, which means one altered copy from either parent can be enough to cause disease, and each child of an affected parent has a 50% chance of inheriting it. In some families, the altered copy appears for the first time in the affected person rather than being passed down from a parent.
What does my IFNGR1 result mean for my family?
Changes in the IFNGR1 gene are linked to rare immune conditions, and the family meaning depends on the exact result because both recessive and dominant patterns are well described. In some families, parents and siblings may be healthy carriers, while in others, a parent, child, brother, or sister may also have the variant and could be affected. Close relatives may want to learn whether the same gene change is present in the family.
Genetic information
Genetic testing
How you find out about variants
To find out whether you carry a variant in the IFNGR1 gene, a clinician can order IFNGR1 genetic testing using a blood sample or saliva sample. A lab reads the gene’s DNA code and looks for variants, then reports whether a finding may help explain a person’s health history and whether family members might also consider testing.
When should I consider getting a genetic test?
You may want to consider testing for changes in the IFNGR1 gene if you or your child has had unusual, severe, or repeated infections from certain bacteria, especially a serious reaction after the BCG vaccine. Testing can also help when these infections start early in life or seem to run in the family.
A genetic result is only one part of your health story
A genetic result can provide valuable insight, but how much it can tell you varies depending on the condition and the kind of variant involved. Many factors, including lifestyle, environment, age, and medical history, shape how the body works over time. For some conditions, especially those influenced 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 can give a clear answer. In areas such as medication response, genetic results may help place individual experiences in context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. Small differences in genes can change how the body breaks down a drug, moves it through the body, or responds to it at its target. This helps explain why the same medication works well for one person, works less well for another, or causes more side effects in someone else. These differences are common and are one reason treatment response can vary from person to person.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences can affect the way people respond to medications. It studies the relationship between genes and drugs to help explain why the same treatment may work differently from one person to another. For many medicines, genes influence either how strongly a drug works or how the body processes it. This information can support more informed and individualized treatment decisions. More detailed information on this topic is available in the LearnHub.
Drugs influenced by the IFNGR1 gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medication response, so general concerns about medicines or new symptoms are best discussed with your doctor.
History
Researchers first identified the IFNGR1 gene in the late 1980s as part of efforts to understand how the immune system responds to interferon gamma, a signaling protein already known to be important in fighting infection. In the 1990s, reports of children with unusual vulnerability to weakly virulent mycobacterial infections led scientists to connect rare IFNGR1 variants with a distinct inherited immune condition. Initially understood only through visible traits, later recognized as tied to a specific gene, this work helped define what is now called Mendelian susceptibility to mycobacterial disease. From these first observations, research expanded steadily. The IFNGR1 gene became an important example in clinical immunology because it showed how a change in one immune pathway could explain a very specific pattern of infection.