Your Skin Barrier and Eczema: When Genetics Leave the Door Open

By Barbara Paldus, PhD, CEO & Founder, Codex Labs

If you live with eczema (also called atopic dermatitis), you’ve probably been told that your skin is “sensitive” or “reactive”. You may feel like your skin overreacts to just about everything: soap, wool, dust, stress, even a change in the weather.

What many people don’t realise is that, underneath all those triggers, eczema is often a skin barrier problem. And for a lot of people, that barrier problem starts with their genes.

In this article, we’ll explore:

• What the skin barrier is
• How it’s supposed to work
• What happens when the barrier is weak
• How genetic “loss of function” mutations can make eczema more likely
• Why good barrier care is so important, especially if eczema runs in your family

What Is the Skin Barrier?

The outermost layer of your skin, called the stratum corneum, is often described as a “brick and mortar” wall.

The “Bricks”

The bricks are flat, dead skin cells called corneocytes.

The “Mortar”

The mortar is a mixture of fats (lipids), including ceramides, cholesterol and fatty acids, which fill the gaps between skin cells.

Together, these structures form a flexible, living barrier that performs two critical jobs:

1. Keeps Water In

This helps your skin stay hydrated and prevents cracking and dryness.

2. Keeps Irritants and Germs Out

The barrier helps protect against:

• Pollution
• Soaps and detergents
• Allergens
• Bacteria
• Viruses
• Fungi

A healthy skin barrier works quietly in the background every day. When it’s functioning well, skin generally feels comfortable, hydrated and less prone to irritation.

What Happens When the Skin Barrier Is Weak?

Imagine a brick wall with missing mortar and broken bricks. Gaps begin to appear, allowing wind and rain to get through.

In skin terms, a weakened barrier means:

More Water Escapes

Moisture leaves the skin through a process called transepidermal water loss (TEWL).

Irritants Can Get In

Soaps, detergents, pollutants and even sweat can cause irritation and stinging.

Allergens Can Sneak Through

Dust mites, pet dander and pollens can penetrate deeper into the skin and interact with immune cells.

Germs Can Take Advantage

Certain bacteria, particularly Staphylococcus aureus, thrive on damaged skin and may worsen inflammation.

This combination of water loss, irritation, allergy and infection risk is commonly seen in eczema.

People with eczema often experience:

• Dry, cracked skin
• Persistent itching
• Red, inflamed patches
• Oozing or crusting lesions
• Thickened areas caused by repeated scratching
• Flare ups that come and go over time

While many different factors can trigger eczema, a weakened skin barrier is often the common thread.

Where Genetics Come In

Your skin barrier is not simply a physical wall. It is a biological structure built and maintained by your genes.

Your genes provide instructions for:

• Proteins that form and hold skin cells together
• Lipids that fill the spaces between cells
• Enzymes that help skin cells mature and shed normally

When some of these instructions are faulty or incomplete, the barrier may not develop or function as effectively as it should.

This is where genetic loss of function mutations come into the picture.

What Is a Loss of Function Mutation?

Think of a gene as a recipe in a cookbook.

A loss of function mutation is like leaving out a key ingredient or step in that recipe:

• The final result doesn’t turn out properly, or
• It may not work at all

In biological terms, a loss of function mutation is a change in DNA that makes a protein less effective or completely non functional.

When this happens in genes involved in skin barrier function, the result can be:

• A thinner, leakier barrier
• Weaker connections between skin cells
• Reduced natural moisture
• Increased opportunities for irritants and allergens to enter the skin

These mutations do not guarantee that someone will develop eczema, but they can increase the risk and may contribute to more persistent disease.

Key Barrier Proteins Involved in Eczema

Scientists have identified several proteins that play important roles in skin barrier function.

Filaggrin

Filaggrin helps bundle structural fibres inside skin cells and later breaks down into natural moisturising factors that help keep the skin hydrated.

Corneodesmosins and Other “Glue” Proteins

These proteins help hold skin cells together and regulate the normal shedding process.

When mutations reduce the function of these proteins, the barrier can become weak and “leaky”.

Filaggrin Mutations and Eczema

Research has shown that certain mutations in the filaggrin gene (FLG) are strongly associated with atopic eczema.

People with FLG mutations often:

• Develop eczema earlier in life
• Experience more persistent symptoms
• Have a higher risk of asthma and hay fever

Why a Leaky Barrier Can Encourage Allergies

When the skin barrier is intact, many allergens:

• Remain on the skin surface
• Wash away naturally
• Never significantly interact with the immune system

When the barrier is damaged:

1. Allergens pass through the skin.
2. They come into contact with immune cells.
3. The immune system may mistakenly identify them as threats.
4. The body becomes sensitised and reacts more strongly over time.

This process helps explain why some children develop what is known as the atopic march, where eczema is followed by:

• Food allergies
• Asthma
• Hay fever

In simple terms, a damaged skin barrier can become the entry point for allergy related conditions.

What This Means for Families

Because some barrier related mutations can be inherited, eczema often runs in families.

If one or both parents have eczema, asthma or allergies, their children may have a higher likelihood of developing eczema.

While this information can feel concerning, it also provides an opportunity for early intervention.

Families can support skin health from birth by:

• Using gentle skincare products
• Moisturising regularly
• Avoiding harsh soaps and irritants
• Seeking medical advice early if symptoms appear

Early attention to skin barrier health may help reduce the severity of eczema in some children.

Genetics Are Not Destiny: Why Skin Care Still Matters

Even if you carry a loss of function mutation, you are not defined by your DNA.

Genes may set the starting conditions, but everyday skin care can make a significant difference.

Support the Skin Barrier

• Use gentle cleansers instead of harsh soaps
• Apply fragrance free moisturisers regularly
• Choose products designed for eczema prone skin

Reduce Triggers

• Avoid very hot baths and showers
• Limit exposure to strong detergents and cleaning products
• Wear soft, breathable fabrics

Work With Your Skin’s Biology

Many modern treatments are designed to support barrier function and reduce inflammation.

These may include:

• Moisturisers and emollients
• Topical corticosteroids
• Calcineurin inhibitors
• Newer biologic therapies

When barrier support is combined with appropriate medical care, many people can:

• Reduce flare frequency
• Improve comfort
• Sleep better
• Improve quality of life

Key Takeaways

✔ Eczema is often linked to a weakened skin barrier.

✔ Genetics can influence how well the skin barrier functions.

✔ Certain mutations, including those affecting filaggrin, are associated with eczema.

✔ A weakened barrier allows moisture to escape and irritants to enter.

✔ Good skin care and barrier support remain essential, regardless of genetic risk.

✔ While you cannot change your genes, you can take practical steps to help protect and support your skin.

About the Author

Barbara Paldus, PhD
CEO & Founder, Codex Labs

Barbara Paldus is a scientist, entrepreneur and skincare innovator focused on skin barrier health and evidence based approaches to managing inflammatory skin conditions, including eczema.