Your skin depends on the FLG gene to build a strong outer barrier that holds in moisture and keeps out irritants, germs, and allergens. This gene helps your body make filaggrin, a protein that helps skin cells fit tightly together. If the gene does not work well, skin can become very dry, rough, or easily irritated. Certain variants are linked to eczema and ichthyosis vulgaris, and they may also increase the chance of allergies or asthma in some people.
What is a gene?
A gene is a stretch of DNA that carries instructions cells can use to make molecules or regulate processes in the body. Some genes give the information needed to produce proteins, the parts of cells that do the work. Others mainly help determine when certain processes happen, where they happen, and how strongly they operate. Taken together, genes affect how the body develops and functions, and they can also shape how you respond to food, stress, or medications. For a deeper look at this topic, you can find more in the LearnHub.
Overview
FLGGene function
What if the gene works
The FLG gene helps make filaggrin, a protein that helps the outer skin layer stay strong and hold moisture. This supports the skin barrier and helps keep out irritants, germs, and allergens.
Risk
What if the gene does not work
Changes in the FLG gene can weaken the skin barrier. Milder variants may cause dry, rough skin, while more severe variants can lead to ichthyosis vulgaris and raise the chance of eczema and other allergic conditions.
Treatment
What does that mean for your treatment
No FLG-specific treatment or management approach is currently established. Care is still chosen based on the skin condition itself, while the FLG gene is being studied as a biomarker of skin barrier weakness and as a possible guide for future skin barrier treatments in eczema and ichthyosis research.
Conditions associated with FLG
Gene function
What if the gene works
Your outer skin depends on the FLG gene to stay sealed and well hydrated. It helps skin cells mature into a tight surface layer that slows water loss and blocks everyday irritants. This also explains what the FLG gene does for the skin barrier in daily life.
In the top layer of skin, the FLG gene helps bundle keratin, a key support protein in skin cells. This lets cells flatten and pack together into a stronger outer surface.
Its protein guides maturing skin cells as they turn into dry, protective surface cells. That step helps the outer layer form a more even, compact shield.
Later, filaggrin is broken down into small natural compounds that attract and hold water in the outer skin. These compounds also support the skin’s usual slightly acidic surface.
What is a variant?
A genetic variant is a minor change in the DNA sequence within a gene. These changes are common and help shape normal human diversity, such as differences 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. Sometimes, though, a variant can change how a gene works more significantly and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the FLG gene often reduce or stop filaggrin production, changing how skin cells mature and weakening the outer barrier. This helps explain how FLG gene variants affect skin barrier function at a cellular level: the protein may be shortened, unstable, or absent. Milder variants may leave some activity, while more severe loss of function variants can be linked to earlier or more persistent dry skin and eczema.
How variants are linked to conditions
Pathogenic variants in the FLG gene can cause ichthyosis vulgaris, a common skin condition marked by dry, rough, scaly skin. FLG gene variants and eczema are also closely linked, and many changes in this gene raise the chance of developing atopic dermatitis. Some people with an FLG gene variant also have a higher likelihood of related allergic conditions, including asthma or food allergy, especially when eczema is present.
A variant is not necessarily a diagnosis
Genetic variants are a routine part of human biology and are widespread in the general population. Most do not have a direct effect on health and instead are part of natural human diversity. For many genes, carrying a variant associated with a condition indicates a possible link rather than a certain diagnosis, especially when several genes and environmental factors are involved. In some situations, though, a single well-characterized variant in a particular gene can be enough to confirm a diagnosis.
Are there things that can increase or change my risk?
For FLG, risk is partly shaped by the variant itself, but the skin environment matters too. Dry air, frequent washing, harsh soaps, fragranced products, and ongoing skin irritation can make skin problems linked to FLG more likely or more severe. A strong family history of eczema, asthma, or allergies can also raise overall risk.
Inheritance of FLG variants
For people looking into how FLG gene variants are inherited, the best-established pattern is for FLG-related ichthyosis vulgaris, which is usually autosomal semidominant. This means a child can inherit the variant from either parent, and one changed copy may cause milder dry, rough skin while two changed copies often lead to more noticeable features. Many carrying this gene change also have a higher chance of eczema, but that risk does not follow a simple one-gene inheritance pattern.
What does my FLG result mean for my family?
A disease-causing FLG change can run in families, so close relatives may also carry the same result. Parents, brothers, sisters, and children can have similar skin findings such as very dry, rough skin or eczema, although symptoms can range from very mild to more noticeable even within the same family. In general, a child of someone with a FLG change has a 1 in 2 chance of inheriting that change.
Genetic information
Genetic testing
How you find out about variants
Testing for variants in the FLG gene usually uses a saliva or blood sample. A lab reads the DNA sequence to look for changes linked with skin barrier conditions; FLG genetic testing for eczema and dry skin can show whether you carry a relevant variant, but results are interpreted alongside symptoms and family history.
When should I consider getting a genetic test?
Genetic testing for the FLG gene may be worth considering if someone has lifelong very dry, rough, scaly skin or a strong family history of an inherited dry skin condition called ichthyosis vulgaris. It can sometimes help confirm the cause, but FLG testing is not usually needed for common eczema alone.
A genetic result is only one part of your health story
A genetic finding can provide useful insight, but how much it explains depends 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. For some conditions, especially those shaped by many genes, genetic information offers context rather than certainty and makes the most sense when considered with other parts of care. In other situations, a genetic result can give a clear answer. For medication response, genetic results can also help put personal experiences in context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. Some people break down a drug faster or slower, while others may be more or less sensitive to its effects. This helps explain why the same treatment can work well for one person but not as well for another, or why side effects can differ. These differences are common and are one reason medication response can vary from person to person.
What is Pharmacogenetics?
Pharmacogenetics looks at how differences in genes can shape a person’s response to medication. It examines links between genes and drugs to better explain why the same treatment may work differently from one person to another. For many medicines, genes affect how strongly a drug works or how the body processes it. This understanding can support treatment decisions that are more informed and more individualized. You can read more about this topic in the LearnHub.
Drugs influenced by the FLG gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding how medicines are chosen or used. If you have concerns about side effects, skin treatments, or whether a medicine is helping, talk with your doctor or pharmacist.
History
The FLG gene came to prominence through research on ichthyosis vulgaris, a common inherited skin condition marked by dry, scaly skin. In 2006, researchers showed that loss of filaggrin was linked not only to ichthyosis vulgaris but also to a higher chance of eczema, which changed how doctors thought about skin barrier problems. From these first observations, research expanded steadily. Scientists then connected FLG variants with the broader “atopic march,” the pattern in which eczema may appear early in life and later be followed by allergies or asthma in some people. That work made the FLG gene an important landmark in modern skin genetics and in the study of allergic disease.