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Filaggrin null mutation associated with atopic dermatitis in children

At-risk children with atopic dermatitis were twice as likely as children without the skin condition to carry the filaggrin null mutation, and they had a greater lifetime prevalence of atopic dermatitis than those with filaggrin wild type in a recent study.

Researchers conducted a prospective, clinical birth cohort study of 411 children born to mothers with asthma as part of the Copenhagen Study on Asthma in Childhood. They followed 397 Caucasian children only (96.6% of the cohort) from birth to age 7 years, which included examinations at a clinical research unit every 6 months and whenever dermatitis exacerbations occurred. At each exam, researchers classified atopic dermatitis (AD) lesions by 35 predetermined anatomical regions, 10 morphological characteristics and SCORAD severity.

Forty-three percent of Caucasian patients developed AD during the study. TaqMan-based allelic discrimination assay was used to genotype filaggrin (FLG) R501X and 2282del4 mutations. Of 170 evaluable children with AD, 15.3% were FLG null mutation carriers, while 7.1% of non-AD children carried the gene (HR=2.23; 95% CI, 1.47-3.39). FLG null genotypes also displayed an association on where they developed AD (primarily exposed skin; cheeks, P=.002; back of hands, P<.0001).

Researchers found children with FLG null mutation had greater SCORAD (44% vs. 31% for moderate-severe AD; P=.14) and more unscheduled visits (mean 3.6 vs. 2.7 visits; P=.036) than wild-type children. Lifetime prevalence of AD was 63% among children with FLG null genotype vs. 43% in children with wild type.

“The FLG null driven AD endotype is characterized by dermatitis at anatomical localizations that tend to be exposed to drying conditions, especially the back of the hands and the cheeks,” the researchers concluded. “Moreover, this endotype had a higher frequency of acute dermatitis episodes … and, also more generalized, and severe dermatitis (higher SCORAD) when compared to FLG wild-type children with AD.”

Researchers said the study may have been limited because all patients were Caucasian, and the possibility exists that FLG mutation may affect other races differently.