Filaggrin is a protein that plays a large part in the protective function of the skin. It is found in the outermost layer of the skin, known as stratum corneum.
It helps keep water inside the skin, and foreign bodies such as bacteria, out of the skin. Mutations in the filaggrin gene can lead to a number of skin problems, from simple dry skin to conditions such as eczema.
In order to understand the role of this protein in the skin, the skin layer where it does most of its work should be explained first. Stratum corneum is the outermost layer of the skin, and it acts as a barrier between us and the world outside. The role of stratum corneum is not just to keep foreign substances from getting into the skin, but also to keep valuable substances, such as water, from escaping.
Filaggrin plays a part in both of these functions of the stratum corneum. It is stored in a different form, called profilaggrin, in the layer of skin just beneath the stratum corneum, called the stratum granulosum. In the transition between the two layers of skin, profilaggrin is turned into filaggrin, where it becomes a part of the lipid envelope.
The lipid envelope is a thin layer between the stratum corneum and the stratum granulosum, which is essential for the barrier function of the skin. In the upper stratum corneum, filaggrin is further divided into amino acids that help retain water in the skin. If filaggrin is unable to perform any of its functions, it may lead to skin problems, including eczema.
Eczema, often used as a synonym for atopic dermatitis, is a chronic skin condition that causes redness of the affected area, itching, swelling, dryness, cracking, blisters, oozing, and possibly bleeding. Eczema can also be a gateway for bacteria and fungi, which cause infections because of the compromised protective function of the skin area affected with eczema.
Although it's still unknown what exactly causes eczema, it is currently believed that there are two major components to the condition:
Immune dysfunction has nothing to do with filaggrin. However, the hereditary proneness of the skin to become dry may have something to do with gene mutations that cause filaggrin deficiency. About half of the people who suffer from a more severe case of eczema have this. This deficiency has also been linked with a number of other atopic conditions, including food allergies, allergic asthma, and allergic rhinitis.
As far as we know, mutations of the filaggrin gene are the most important genetic risk factor for atopic dermatitis. Further research is being done on the exact role of these mutations in the development of this disorder. There's a lot of hope that by understanding these mechanisms, better treatment options for atopic dermatitis, as well as other conditions that are caused by the mutations, will develop.
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