The IFITM3 gene helps your cells block certain viruses from entering, especially during the body’s early immune response. If it does not work as well, some people may be more likely to develop more severe viral illness, particularly influenza. What this gene does can influence how your body handles infections, but genes are only one part of the picture. The IFITM3 gene drew wider attention during flu outbreaks and again during COVID-19 research, when scientists studied whether common variants might affect illness severity.
What is a gene?
Genes are stretches of DNA that carry instructions your cells use to make molecules or regulate processes in the body. Some genes contain the code for proteins, the parts of cells that do much of the work. Other genes mainly help direct when certain processes happen, where they happen, and how strongly they run. Taken together, genes influence how the body develops and functions, and they can shape how you respond to food, stress, or medications. For a deeper look at this topic, you can learn more in the LearnHub.
Overview
IFITM3Gene function
What if the gene works
The IFITM3 gene helps your cells block some viruses from getting fully inside cells. Its protein works at cell membranes and in small cell compartments to make viral entry harder.
Risk
What if the gene does not work
If the IFITM3 gene does not work properly, cells may be less able to block viruses from entering through internal membrane compartments. Milder or more severe variants can reduce this barrier to different degrees.
Treatment
What does that mean for your treatment
For pathogenic or loss-of-function variants in the IFITM3 gene, no gene-specific treatment or drug choice is currently established in clinical guidelines. The IFITM3 gene is being studied as a marker of viral infection severity and in some cancers, but this has not yet changed routine care.
Gene function
What if the gene works
Your cells use the IFITM3 gene as part of their early defense against viruses. Its protein works mainly on membranes inside the cell, where incoming viruses are often processed. Understanding how the IFITM3 gene helps protect cells from viruses makes its day to day role easier to picture.
The IFITM3 gene helps stop certain viruses after they are taken into the cell. Its protein makes it harder for the virus and the cell membrane to merge, so the virus cannot easily release its genetic material.
This protein gathers in small membrane compartments called endosomes (sorting sacs inside cells). There, it helps keep those membranes less easy for viruses to cross.
Your cells can make more IFITM3 protein after interferon signals, part of the body’s early antiviral alarm system. This helps prepare cells to resist viral entry during an infection.
What is a variant?
A genetic variant is a small difference in the DNA sequence of a gene. These changes are common and are part of normal human diversity, including differences in appearance, metabolism, and how the body responds to environmental influences. Many variants do not have any noticeable effect and simply represent natural genetic variation. Sometimes, though, a variant can change how a gene works more substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the IFITM3 gene can change how well the protein blocks viral entry into cells. Some changes lower how much protein the cell makes, while others alter its shape, stability, or placement on internal cell membranes, so it works less efficiently. Milder variants may only partly reduce this effect, while more severe variants can cause a larger loss of activity and weaker control of virus fusion inside the cell.
How variants are linked to conditions
The IFITM3 gene does not yet have a broadly confirmed link to a specific health condition, though this can change as research develops. Research on how IFITM3 gene variants are linked to conditions is still developing, so anyone with a confirmed IFITM3-related diagnosis should rely on guidance from their doctor or genetic counselor rather than general information.
A variant is not necessarily a diagnosis
Genetic variants are a routine part of human biology and are common across the general population. Most do not have a direct effect on health and instead reflect natural human diversity. In 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?
Some IFITM3 changes have been linked with a higher chance of more severe viral illness, especially with flu, but this does not determine what will happen on its own. Age, pregnancy, immune health, and long-term conditions such as asthma, heart disease, or diabetes can also strongly affect overall risk.
Inheritance of IFITM3 variants
There is not yet a broadly confirmed Mendelian inheritance pattern for IFITM3 tied to one specific human condition, so how IFITM3 variants are inherited in a disease causing sense is still being clarified. Most reported IFITM3 changes are studied as risk modifiers, meaning they may influence susceptibility rather than directly determine that someone will develop a condition. The IFITM3 gene is located on chromosome 11, which is an autosome, so you inherit one copy from each parent.
What does my IFITM3 result mean for my family?
There is not yet a broadly confirmed inherited pattern tied to a specific medical condition for IFITM3, even though some changes in this gene have been studied for their possible effects on how the body responds to certain infections. If you have a specific IFITM3 result and want to know what it could mean for close relatives, a doctor or genetic counselor can help explain it in the context of your family history.
Genetic information
Genetic testing
How you find out about variants
Genetic testing for IFITM3 variants usually uses a blood or saliva sample. The lab reads the IFITM3 gene’s DNA code, most often by sequencing, to check for changes and compare them with reference data. Results may show a known variant, a likely harmless variant, or a finding whose meaning is still being clarified.
When should I consider getting a genetic test?
There isn’t yet a broadly established, IFITM3-specific clinical reason for genetic testing. Decisions about testing are best made with a doctor or genetic counselor, based on your health history, family history, and the reason testing is being considered.
A genetic result is only one part of your health story
A genetic finding can provide useful insight, yet what it can tell you varies based on the condition and the type of variant involved. Many factors, including lifestyle, environment, age, and medical history, affect how the body functions over time. For some conditions, especially those shaped by many genes, genetic information provides context rather than certainty and is best understood together with other parts of care. In other situations, a genetic result can offer a clear answer. In areas such as medication response, these results can also 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 DNA can change how the body absorbs, breaks down, transports, or reacts to a drug, so the same treatment may work better for one person than for another. These differences are common and can influence how much benefit someone gets from a medicine or how sensitive they are to side effects.
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 how strongly a drug works or how the body handles it. This understanding can support more informed, individualized treatment decisions. More detail on this topic is available in the LearnHub.
Drugs influenced by the IFITM3 gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in predicting how medicines will work or what side effects they may cause. Questions about your medications, side effects, or general health are best discussed with your doctor.
History
Researchers first identified the IFITM3 gene while studying how cells respond to interferon, a natural signal the body uses during infections. In recent decades, awareness of this gene’s role has grown as scientists linked it to differences in how people respond to viral illnesses, especially influenza. A major step came in the early 2010s, when studies suggested that certain IFITM3 variants were associated with a higher chance of more severe flu. From these first observations, research expanded steadily into other infections, including COVID-19. This history made the IFITM3 gene part of a broader effort to understand why infections affect people so differently.