Background: The prevalence of atopic disease, which consists of conditions such as atopic dermatitis, allergies, and asthma, has been on the rise in recent decades. In children, atopic dermatitis often acts as an initial manifestation of atopic disease and frequently precedes the development of food allergies, asthma, and allergic rhinitis. Mutations in the FLG gene, encoding the fillagrin precursor profillagrin, serve as a genetic risk factor for these diseases. Approximately 25%–50% of individuals with atopic dermatitis carry FLG mutations. It has been proposed that FLG mutations exhibit variations specific to different populations, indicating distinct patterns within each population.

Severe allergic symptoms could indicate the presence of an underlying immunodeficiency or immune dysregulation and in patients with severe, early-onset, or simultaneous allergic conditions, these could be suggestive of an underlying Primary Atopic Disorder. Specifically, the allergic triad characterized by elevated IgE levels, eosinophilia, and eczema is a common feature in various inborn errors of immunity that could be mistakenly diagnosed as severe allergic conditions.

Method: Our patient’s medical record was analyzed retrospectively, including her medical history, as well as results from immune laboratory tests and genetic analyses.

Results: We present a 9-year-old female of mixed ethnicity with a history severe eczematous rash diagnosed with atopic dermatitis. Whole exome sequencing analysis revealed an initially novel heterozygous variant in the FLG gene (NM_002016: EXON3:c.C2218T: p.R740X).

Conclusion: Healthcare providers caring for patients with atopic dermatitis and recurrent staphlococcus infections should be aware of the significant link between filaggrin gene mutations and the development of severe, persistent atopic dermatitis that begins in childhood, as well as its association with recurring staphlococcus infections. Additionally, they should keep in mind that certain inborn errors of immunity may predominantly manifest as severe and treatment-resistant atopic disorders.

Statement of novelty: We have identified a rare variant in the FLG gene associated with severe atopic dermatitis and allergies.