What is Filaggrin and How Does it Relate to Eczema?

What is Filaggrin and How Does it Relate to Eczema?

Jennie Lyon

Dry Skin, Eczema, and Filaggrin – How it Relates to You or Your Eczema Child.

What is Filaggrin?

Filaggrin is a protein that is vital for skin cells to mature properly into the tough, flat corneocytes that form the outermost protective layer of our skin. This skin is called the cornified cell envelope (CCE).

Three years ago, a ground-breaking publication was released that showed the importance of the Filaggrin. The publication came from Professor Irwin McLean’s group and showed that lack of the Filaggrin protein in the skin causes ichthyosis vulgaris, a type of dry skin condition that is strongly linked to the development of atopic eczema. Many studies have taken place since that time that corroborate Professor McLean’s original study.

At least 20 loss-of-function mutations at the gene level have been found in various racial groups that are shown to cause a deficiency in Filaggrin. Filaggrin deficiency and impaired skin–barrier function is strongly connected to the development of atopic eczema. Most of us carry at least one gene that predisposes us to atopic eczema but if you inherit several different predisposing genes then you are much more likely to develop atopic eczema. This is made even more likely when you’re exposed to certain environmental factors. These factors include the Western style of living, particularly in industrial areas, and exposure to hard water. The combination of these environmental factors and a Filaggrin deficiency will put you at higher risk in developing eczema.


The dry, scaly patches of eczema are an indication that the barrier function of the skin is not working properly. Once the skin barrier has been breached, irritants such as soaps and detergents can dry the skin out and cause deterioration of the already weakened barrier. This causes eczema to become even worse. It also puts the skin at greater risk of exposure to food and inhalant allergens that penetrate the upper layers of the skin. It’s extremely important to repair the skin barrier with the use of emollients and wet wrap therapy.

Filaggrin deficiency occurs when the skin inherits a faulty copy of the gene for making Filaggrin. These gene faults are known as Filaggrin loss-of-function mutations. Possession of a Filaggrin loss-of- function gene from a parent means around a 50% reduction in the amount of Filaggrin produced in the skin. In addition to eczema, there is a growing body of evidence to suggest that Filaggrin deficiency may be associated with the development of food allergy and cat allergy. Funny enough, exposure to dogs early in life may be protective against the development of eczema, though this has not been fully substantiated yet.

You might wonder if everyone with atopic eczema has a Filaggrin deficiency. Surprisingly, no. It seems that just over half (56%) of people with moderate to severe eczema have Filaggrin deficiency. As new mutations are discovered, this figure continues to rise. However, only 15% of those with mild to moderate eczema can be explained by Filaggrin deficiency. There are no routine laboratory tests for Filaggrin deficiency and it is mainly being used as a research tool, although it is likely that they will become available.

Unfortunately, Filaggrin deficiency cannot be corrected. However, there is some work under way to look for ways to introduce Filaggrin back into the skin. More research and development is needed.

You can take the following measures to protect your skin’s barrier: