The FLG gene, or filaggrin gene, provides instructions for the creation of the filaggrin protein. This protein is located in the outermost layer of the skin, the epidermis, and plays a significant role in its structure. The proper functioning of the FLG gene and the resulting filaggrin protein are important for maintaining healthy skin.
The FLG Gene’s Role in Skin Health
The FLG gene produces profilaggrin, a large protein found in the epidermis. Profilaggrin is then broken down into multiple copies of the filaggrin protein. Filaggrin plays a direct role in creating a robust skin barrier, defending against environmental irritants and allergens while minimizing water loss from the body.
Filaggrin works by binding together structural proteins within the outermost skin cells, creating tight bundles. This process flattens and strengthens these cells, forming a resilient barrier. Additionally, filaggrin undergoes further processing, breaking down into components that contribute to the skin’s “natural moisturizing factor” (NMF). These molecules retain water within the skin, maintaining its hydration. The skin barrier helps to prevent moisture from escaping and protects the body from foreign substances such as toxins, bacteria, and allergens like pollen and dust mites.
Health Conditions Linked to FLG Gene Variations
Variations in the FLG gene are strongly linked to skin conditions, primarily Ichthyosis Vulgaris and Atopic Dermatitis, also known as eczema. These variations can lead to the production of an abnormally short profilaggrin molecule, which cannot be properly processed into functional filaggrin proteins. This shortage of filaggrin impairs the skin’s barrier function and reduces the natural moisturizing factor, resulting in dry, scaly skin.
In Ichthyosis Vulgaris, the lack of filaggrin and its breakdown products causes dry, scaly skin. Atopic Dermatitis, characterized by dry, itchy skin and red rashes, is also strongly associated with FLG gene variations. About 20% to 30% of individuals with atopic dermatitis have an FLG gene variation.
A compromised skin barrier due to filaggrin deficiency can increase susceptibility to other allergic disorders. Individuals with FLG gene variations, particularly those with atopic dermatitis, have an increased likelihood of developing conditions like asthma, hay fever, and food allergies. The impaired barrier allows allergens to penetrate the skin more easily, potentially triggering these systemic allergic reactions.
How FLG Gene Variations Are Inherited
Variations in the FLG gene are passed down through families following an autosomal semi-dominant inheritance pattern. This means the gene responsible is located on one of the non-sex chromosomes. In this pattern, inheriting just one copy of a mutated FLG gene can increase an individual’s risk for conditions like atopic dermatitis, though the symptoms may be mild or only appear seasonally.
If an individual inherits two mutated copies of the FLG gene, the resulting condition tends to be more severe and may be present year-round. For instance, in Ichthyosis Vulgaris, having one affected gene typically results in very mild dry skin, while having two affected genes leads to a more pronounced ichthyosis. This semi-dominant pattern highlights that the number of affected alleles can influence the severity of the phenotype.
Support and Management for FLG-Related Conditions
Managing skin conditions linked to FLG gene variations focuses on supporting the skin barrier and alleviating symptoms. Regular and consistent moisturizing is a primary strategy, as it helps to repair and maintain the skin’s protective function. Thick ointments or creams are often preferred over lotions, especially after short lukewarm baths, to maximize hydration and create a protective layer.
Individuals should also avoid known irritants and allergens that can trigger flare-ups. Common triggers include certain soaps, detergents, fragrances, and fabrics like wool. Consulting a dermatologist is beneficial for personalized skin care plans and to explore specific products, including those containing ceramides or ingredients that may help boost filaggrin levels or restore the natural moisturizing factor. While direct filaggrin replacement therapies are still being researched, emerging approaches include topical treatments aimed at enhancing filaggrin expression or function, and systemic treatments targeting inflammation.